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Despite the crucial role of the Southern Hemisphere (SH) westerlies in modulating modern and past climate evolution, little is known about their behavior and possible forcing mechanisms during the early Cenozoic. We probe changes in the hydroclimate of southwest Australia during 62–51 Ma, based on sedimentary proxy records from the International Ocean Discovery Program Site U1514 in the Mentelle Basin. Our results reveal a transition from a less humid climate to wetter conditions at mid–high latitudes starting from the early Eocene, which suggests poleward migration of the SH westerlies. This long‐term trend is punctuated by short‐lived events of aridification during the Mid‐Paleocene Biotic Event and wetter intervals during the Paleocene‐Eocene Thermal Maximum, indicating additional short‐term meridional shifting of the westerlies. We propose that the evolution of SH westerlies was driven by the equator‐to‐pole temperature gradient regulated by global warming and ephemeral growth of the Antarctic ice sheet. Plain Language Summary: The Southern Hemisphere (SH) westerlies, which are the dominant atmospheric circulation patterns in the middle latitudes, play a key role in regulating global and regional climate. Currently, the knowledge of past changes in SH westerlies relies mainly on the late Quaternary. Its dynamics over longer timescales, especially under early Cenozoic greenhouse climate states, remain poorly understood. The Mentelle Basin off southwest Australia was located at a more southerly location than at the present day, and was potentially under the influence of SH westerlies. To examine the long‐term hydroclimate changes in southwest Australia during the mid‐late Paleocene to the early Eocene (62–51 Ma), we measured neodymium and hafnium isotopic compositions of fine‐grained detrital sediments from a borehole (IODP Site U1514) drilled in the Mentelle Basin, in addition to clay mineralogy, and elemental abundances. Our results suggest a gradual wetting of southwest Australia since the early Eocene, which we relate to the poleward migration of SH westerlies in response to a reduced latitudinal temperature gradient. An abrupt northward shift of SH westerlies was observed during the short‐lived Middle Paleocene Biotic Event (∼59 Ma), possibly driven by ephemeral growth of the Antarctica ice sheet. Key Points: We reconstruct the hydroclimate evolution of southwest Australia during 62–51 MaThe Southern Hemisphere (SH) westerlies remained relatively stable during the mid‐late Paleocene and shifted poleward since the early EoceneProcesses related to variations of pole‐equator temperature gradients drove meridional migration of the SH westerlies [ABSTRACT FROM AUTHOR]

Oxygen-induced retinopathy (OIR) animal model is widely used for retinopathy of prematurity (ROP) researches. The purpose of this study was to identify proteins and related pathways of OIR with or without anti-vascular endothelial growth factor (VEGF) treatment, for use as biomarkers in diagnosing and treating ROP. Nine samples were subjected to proteomic analysis. Retina specimens were collected from 3 OIR mice, 3 OIR mice with anti-VEGF treatment and 3 normal mice (control group). Liquid chromatography-tandem mass spectrometry analysis was performed using the 4D label-free technique. Statistically significant differentially expressed proteins, gene ontology (GO) terms, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway representations, InterPro (IPR) and protein interactions were analyzed. In total, 4585 unique proteins were identified as differentially expressed proteins (DEPs). Enrichment analysis of the GO and KEGG indicated functional clusters related to peptide biosynthetic and metabolic process, cellular macromolecule biosynthetic process and nucleic acid binding in OIR group. For anti-VEGF treatment group, DEPs were clustered in DNA replication, PI3K/Akt signaling pathway and Jak/STAT signaling pathway. Proteomic profiling is useful for the exploration of molecular mechanisms of OIR and mechanisms of anti-VEGF treatment. These findings may be useful for identification of novel biomarkers for ROP pathogenesis and treatment. [ABSTRACT FROM AUTHOR]

At present, the seasonal melting and expansion of the Antarctic ice sheet affect the location and intensification of the westerlies, as well as the precipitation and continental weathering and erosion in southwest Australia. The Miocene was an important period when the Earth's climate state transitioned from a warmhouse to an icehouse and the East Antarctic Ice Sheet underwent large-scale melting and expansion. At that time, Australia was closer to the Antarctic region than it is now. This makes Australia an ideal target area for studying the coupling relationship among the atmosphere, hydrosphere, lithosphere, and cryosphere. Based on the comprehensive analysis of the siliciclastic mass accumulation rate, grain size, clay minerals, and elemental composition of the sediments at Site U1516 of the International Ocean Discovery Program Expedition 369, we reconstructed the Miocene climate evolution and the continental weathering and erosion history of southwest Australia on a tectonic time scale. Our indicators show that the climate was dry and that continental weathering and erosion were weak, with a small amount of terrestrial material transported to the ocean during the Early to Middle Miocene (22–12.7 Ma). However, as mentioned in previous studies of nearby sites, precipitation and river runoff increased prominently with enhanced continental weathering at 12.7–8 Ma, which was related to the northward migration or intensification of the westerlies, possibly due to increased sea ice in the Southern Ocean. In addition, we found that the evolution of the South Asian monsoon and the westerly belt were synchronized in the Miocene, which indicates that the South Asian monsoon system at that time may also have been affected by the high-latitude signals of the Southern Hemisphere. We speculate that the significant decrease in deep-sea temperature and the expansion of the surface sea temperature gradient in latitude and longitude until the permanent East Antarctic Ice Sheet formed (∼12.8 Ma) played an important role in the transmission of Antarctic signals to low latitudes. [ABSTRACT FROM AUTHOR]

Oceanic anoxic event 1d (OAE 1d) has been well studied at northern low latitudes (i.e., in Tethys and the North Atlantic); however, the paleoenvironmental response to this event at high latitudes has not been documented and the triggering mechanism remains unknown. Here, we address both of these shortcomings by presenting the first detailed sedimentary and multi‐proxy geochemical record of the OAE 1d at southern high latitudes (60–62°S), obtained from sediments using Site U1513, IODP Expedition 369. Biostratigraphic and chemostratigraphic data support correlation of the interval studied with OAE 1d, and the sedimentary mercury proxy reveals that at least at Site U1513, OAE 1d is associated with the Central Kerguelen large igneous province volcanism. Furthermore, the significant increase in continental runoff and consequent terrigenous input from southwestern Australia in the southeastern proto‐India Ocean might have resulted in regionally weakened bottom‐water oxygenation and strengthened organic matter burial during OAE 1d. Plain Language Summary: Geological marine records hold valuable information that could inform predictions for the future of our warming world. Marine sediments are an important reservoir of the global organic carbon and changes at the seafloor can modulate release of CO2 into the atmosphere. Cretaceous oceanic anoxic event 1d (∼latest Albian) was a significant disturbance to the global carbon cycle in the mid‐Cretaceous although it is poorly documented in the southern hemisphere especially at high latitudes. Our integrative sedimentary‐geochemical study demonstrates that oceanic anoxic event 1d at southern high latitudes might have been directly triggered by Central Kerguelen large igneous province volcanism. Volcanic emissions are proposed to have shifted the climate such that runoff and input of terrigenous sediment from southwestern Australia increased. These changes would have weakened bottom‐water oxygenation and increased organic matter burial in the southeastern proto‐Indian Ocean. Key Points: We present the first sedimentary and geochemical records for oceanic anoxic event 1d at southern high latitudes (60–62°S)Environmental changes during oceanic anoxic event 1d might be directly triggered by Central Kerguelen large igneous province volcanismMultiple paleoenvironmental changes occurred in the study area during oceanic anoxic event 1d [ABSTRACT FROM AUTHOR]

• A comprehensive Hg and Os isotopic record was reconstructed for the entire Eocene. • Isotopic signals indicate enhanced volcanism and continental weathering in the mid-Eocene. • A prolonged warmth lasting for ∼5 Myr is identified in the mid-Eocene. • A clear link between continental weathering and climate is evident during the MECO. • The Eocene climate is closely linked to active plate tectonic-driven volcanic activity. Rapid plate reorganization may have influenced global climate during the Eocene; however, its linkage remains poorly constrained, particularly during the middle Eocene. To elucidate this tectonic–climatic relationship, here, we conducted a comprehensive analysis based on high-resolution mercury (Hg) and osmium (Os) abundance and isotope data obtained from the complete Eocene sedimentary sequence of Site U1514, drilled in the Mentelle Basin off southwest Australia. The Hg signals in this sedimentary sequence, which are characterized by significantly high enrichment and insignificant mass-independent fractionation (Δ199Hg) signal, confirm that the middle Eocene (∼45–38 Ma) was a period of persistent, increased volcanism, accompanied by intense tectonic activity. In particular, a remarkable seafloor volcanic eruption persisted for approximately 1.5 million years (∼42.0–40.5 Ma), immediately preceding the Middle Eocene Climate Optimum (MECO). Contemporaneously, the trends toward a slightly more radiogenic seawater 187Os/188Os (Os i) composition denote the prevalence of intensified continental weathering under a warm, humid climate during the middle Eocene, a phenomenon particularly evident during the MECO. Importantly, the Hg and Os records from Site U1514 reveal the occurrence of a multi-million-year warming reversal amid the long-term Eocene cooling trend, which likely contributed to significant CO 2 reduction during the late Eocene. These findings significantly enhance our understanding of Eocene climate dynamics, which are fundamentally linked to intensive tectonic-driven volcanic activity and associated continental chemical weathering. [ABSTRACT FROM AUTHOR]

Purpose: To observe retinal sensitivity (RS) and microvasculature changes in preoperative and postoperative idiopathic macular epiretinal membrane (iERM) with optical coherence tomography (OCT) classification by microperimetry (MP) and optical coherence tomography angiography (OCTA). Methods: In this retrospective study, 53 eyes of 53 patients affected with iERM were enrolled and 35 iERM eyes underwent pars plana vitrectomy associated with internal limiting membrane peeling. All iERM eyes were evaluated and graded by OCT. According to the thickness of the fovea relative to the surrounding macula from OCT radial line scans, we classified iERM into 3 grades. MP was used to measure RS of macular within 20° centered on the fovea and fixation stability (FS). OCTA was used to measure the superficial and deep capillary plexus (DCP) layers using 6 mm × 6 mm scans. Measurements were taken at the baseline visit and 3-month postoperation. Evaluated factors included: best corrected visual acuity, RS, FS, vessel density. Results: Eyes with iERM had worse RS than control eyes (p < 0.0001), especially in higher grade iERM eyes. And higher grade iERM eyes had a marked increase foveal vessel density (FVD) (p < 0.0001) in superficial capillary plexus (SCP) and DCP, and a significant decrease parafoveal vessel density (Para VD) in DCP. After surgery, there was no difference in RS and FS than preoperation (p > 0.05), whether in grade 1 or 2 iERM eyes. However, in OCTA analyses, grade 1 iERM eyes had less whole vessel density (WVD) and perifoveal vessel density (Peri VD) in SCP, than preoperation (p < 0.05). And grade 1 iERM eyes had higher Para VD and Peri VD in DCP (p < 0.05), than preoperative OCTA results. Grade 2 iERM eyes had less WVD, FVD, and Peri VD in SCP, than preoperation (p < 0.05). After surgery, in grade 2 iERM eyes, there was a positive correlation between whole retinal sensitivity and WVD (p < 0.05) in SCP. And there were positive correlations between Para RS and Para VD (p < 0.05), Peri RS and Peri VD (p < 0.05) in SCP. Conclusions: Classification helps to reveal different changes in iERM eyes. Higher grade iERM eyes had worse RS and microvasculature changes. MP and OCTA play an important role in assessing iERM and help surgical decisions for patients with iERM. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate pre‐ and postoperative microvasculature features in eyes with different idiopathic macular epiretinal membrane (iERM) classifications using optical coherence tomography angiography (OCTA). Methods: In this retrospective study, 100 eyes with iERM were enrolled; 62 eyes underwent pars plana vitrectomy (PPV). All iERM eyes were evaluated and graded using optical coherence tomography (OCT). According to the thickness of the fovea relative to the surrounding macula from OCT radial line scans, we classified iERM into three grades. Optical coherence tomography angiography (OCTA) was used to measure the foveal avascular zone (FAZ)‐related parameters and the superficial and deep capillary plexus layers using 3 × 3 mm scans. Measurements were taken at baseline and 3 months postoperatively. Best corrected visual acuity (BCVA), vessel density (VD), FAZ area, FAZ perimeter (PERIM), acircularity index (AI), and foveal vessel density (FD) were evaluated. Results: Idiopathic macular epiretinal membrane (iERM) eyes with a higher grade had a lower FAZ area and perimeter (p < 0.0001), higher foveal vessel density (FVD) both in the superficial capillary plexus (SCP) (p < 0.0001) and in the deep capillary plexus (DCP) (p < 0.05), and a lower parafoveal vessel density (PRVD) in the DCP (p < 0.0001). The macular vessel density ratio (MVR = FVD/PRVD) increased with an increase in grade both in the SCP and in the DCP (p < 0.0001). For grade 1 iERM eyes, only PRVD in the DCP significantly changed before versus after the operation (p < 0.05). For grade 2 iERM eyes, the FAZ area and perimeter became larger after the operation (p < 0.05). The MVR of grade 2 iERM eyes decreased postoperatively both in the SCP (p < 0.05) and in the DCP (p < 0.001). For grade 1 and grade 2 iERM eyes, preoperative LogMAR BCVA was negatively correlated with the FAZ area (p < 0.01) and perimeter (p < 0.01), and was positively correlated with the MVR in the SCP (p < 0.05). Postoperative LogMAR BCVA was positively correlated with the FVD in the DCP (p < 0.05). Conclusions: Idiopathic macular epiretinal membrane (iERM) eyes of different grades have significant differences in microvasculature features. According to OCTA, eyes with higher grades have more serious microvascular changes. Grading plays a part in predicting postoperative microvascular characteristics, and grade 1 iERM eyes have a better visual outcome compared with grade 2 iERM eyes. [ABSTRACT FROM AUTHOR]

We present a new set of clay mineral and grain-size data for the siliciclastic sediment fraction from International Ocean Discovery Program (IODP) Site U1456 located in the eastern Arabian Sea to reconstruct the variabilities in the continental erosion and weathering intensity in the western Himalaya, elucidate the sediment source-to-sink processes and discuss the potential controls underlying these changes since 3.7 Ma. The clay minerals mainly consist of smectite (0–90%, average 44%) and illite (3–90%, average 44%), with chlorite (1–26%, average 7%) and kaolinite (0–19%, average 5%) as minor components. The compositional variations in the clay minerals at IODP Site U1456 suggest four phases of sediment provenance: the Indus River (phase 1, 3.7–3.2 Ma), the Indus River and Deccan Traps (phase 2, 3.2–2.6 Ma), the Indus River (phase 3, 2.6–1.2 Ma) and the Indus River and Deccan Traps (phase 4, 1.2–0 Ma). These provenance changes since 3.7 Ma can be correlated with variations in the Indian summer monsoon intensity. The siliciclastic sediments in the eastern Arabian Sea were mainly derived from the Indus River when the Indian summer monsoon was generally weak. In contrast, when the Indian summer monsoon intensified, the siliciclastic sediment supply from the Deccan Traps increased. In particular, this study shows that the smectite/(illite+chlorite) ratio is a sensitive tool for reconstructing the history of the variation in the Indian summer monsoon intensity over the continents surrounding the Arabian Sea since 3.7 Ma. [ABSTRACT FROM AUTHOR]

We investigated the microscopic mineral characteristics of modern eolian dust particulates and the trace-element compositions of the siliciclastic fractions of these samples, collected from the Philippine Sea in 2014 and 2015, and conducted an air mass backwards trajectory analysis of dust particulates in the spring and winter of 2015, to better constrain the provenances and transport dynamics of dust delivered to this region. The microscopic minerals show obvious signatures of dust deposition and physical abrasion, indicating long-distance wind transport from the Asian deserts. The trace-element compositions (Zr–Th–Sc) display a binary mixture of eolian materials derived from the eastern Asian deserts and the central Asian deserts, which is similar to the result of the Sr–Nd isotopic compositions of modern sediment trap sediments collected on the Benham Rise in 2015. We demonstrate that modern dust sediments in the Philippine Sea primarily originate from the Ordos Desert (generally > 80%), while the contributions of the Taklimakan Desert and the Badain Jaran Desert are small. Eolian dust particulates raised from source regions are predominantly transported to the Philippine Sea by the East Asian winter monsoon, but not by the westerlies. In addition, our results indicate that increased precipitation in the source regions can result in relatively low dust fluxes in the Philippine Sea, and there is a period of 6–7 days for eolian dust originating from source areas to be delivered to the Philippine Sea. [ABSTRACT FROM AUTHOR]

• First millennial-scale study on erosion and weathering of the western Philippine Sea. • Sea-level lowstand favored erosion and weathering of exposed shelf sediments. • Anthropogenic activity has been a dominant control on Luzon erosion since 2.1 ka. Multiproxy records from Core MD06-3054 in the western Philippine Sea and published results from the nearby Core MD06-3052, which are both located at the northern margin of the Western Pacific Warm Pool (WPWP), provide precise reconstructions and evidence for the potential controls on continental erosion and weathering intensities in Luzon. These data also constrain sediment source-to-sink processes in the sea since 27 ka at the millennial scale. We demonstrate that the siliciclastic fraction is derived from Luzon volcanic rocks and eolian dust from mainland Asia. Stronger physical erosion and chemical weathering generally occurred during the last glaciation, Heinrich Event 1, the Younger Dryas, and the period from 10.3 to 11.3 ka. In contrast, the Bølling-Allerød was characterized by weaker physical erosion and chemical weathering. During the last glaciation, Heinrich Event 1, and the Younger Dryas, the lower sea level led to enhanced erosion and weathering of the exposed shelf sediments. In contrast, the weaker physical erosion and chemical weathering that occurred during the Bølling-Allerød and the Holocene, except after 2.1 ka, are closely correlated with the higher sea level. The stronger physical erosion and chemical weathering at 10.3–11.3 ka may be derived from the reworking of older sediments during the time of a strengthening summer monsoon. Furthermore, enhanced human activity since 2.1 ka has become the dominant control on erosion in Luzon. Rapid weathering changes in the WPWP during the last deglaciation highlight the high variability in local controls at low latitudes during these periods and the potential influence of controls at high latitudes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The evolution of the Indian summer monsoon was reconstructed from IODP Site U1456. • The clay-sized detrital sediments are derived from Indus River and Deccan Traps. • A major transition recorded by clay mineralogy at ~0.9 Ma corresponds to the MPT. Abstract Clay mineral assemblages at International Ocean Discovery Program Expedition 355 Site U1456 drilled in the eastern Arabian Sea have been investigated to reveal the sediment provenances and reconstruct the erosion/weathering patterns in the western Himalaya and Indian subcontinent, thus constraining the evolution of the Indian summer monsoon and its forcing mechanism since 1.2 Ma. The clay mineral assemblages at Site U1456 mainly comprise smectite (with an average value of 59%) and illite (with an average value of 33%), with chlorite (with an average value of 5%) and kaolinite (with an average value of 3%) as minor constituents. In terms of sediment provenance, our results indicate that illite and chlorite are predominantly derived from the Indus River, which originates from the western Himalaya and Karakoram, while smectite is primarily sourced from the Narmada River and Tapti River in the Deccan Traps, with a non-negligible contribution from the Indus River in some cases. Variations in smectite/(illite + chlorite) ratio are ultimately controlled by the Indian summer monsoon, which is characterized by approximate glacial/interglacial cyclicity, showing higher values (i.e., enhanced chemical weathering) during interglacial periods. In addition, a major shift in smectite/(illite + chlorite) ratio at 0.9 Ma is correlated to the Mid-Pleistocene Transition (∼1.2–0.9 Ma). Both the Marine Isotope Stage 13 event (533–478 ka) and the Mid-Brunhes Event (∼430 ka) are also recorded in the clay mineral proxies. Based on the spectral analysis, smectite/(illite + chlorite) ratio displays a transition from nonprimary periodicity (29-kyr) to strong eccentricity (100-kyr) and precession (22-kyr) periodicities at approximately 0.9 Ma, which corresponds to the Mid-Pleistocene Transition. Our study indicates that the variability of the Indian summer monsoon at orbital timescales is controlled by high-latitude (i.e., ice volume) and low-latitude (i.e., summer insolation) processes. [ABSTRACT FROM AUTHOR]

We present a new high-resolution multiproxy data set of mass accumulation rates, Sr-Nd isotopes, as well as major and trace elements for the siliciclastic sediment fraction from International Marine Global Change Study Core MD06-3052, located on the continental slope of the western Philippine Sea. We integrate our new data with published grain sizes and sea surface temperatures from the same core, as well as with Equatorial Pacific sea level, and East Asian summer monsoon precipitation, in order to constrain at high-resolution changes in physical erosion and chemical weathering intensities on Luzon, and sediment source-to-sink processes. We assess the potential significance of chemical weathering of arc silicates in regulating global atmospheric CO 2 since 156 kyr BP. Sr-Nd isotopes show that the siliciclastic sediments were dominantly sourced from volcanic rocks exposed on Luzon (~ 68–100%), with a lesser contribution from Asian dust (~ 0–32%). Different indices indicate that stronger physical erosion and chemical weathering occurred during Marine Isotope Stage (MIS) 6 (130–156 kyr BP), as well as in the latter stage of MIS 3 and MIS 2 (14–40 kyr BP). The large sea-level lowstands and associated significant exposure of continental shelf in the western Philippine Sea during these two cold periods should favor physical erosion and chemical weathering of unconsolidated sediments on the exposed shelf. Furthermore, we notice the relatively good coherence between chemical weathering intensities on Luzon and global atmospheric CO 2 concentrations over these cold intervals. We suggest that strengthening of chemical weathering of silicates on Luzon and other tropical arcs (within 20° of the Equator) during the Quaternary glacial sea-level lowstands may significantly contribute to the lowering of atmospheric CO 2 concentrations during ice ages. We estimate that a significant fraction, up to ~ 16% (i.e., ~ 8 ppmv), of all atmospheric CO 2 ultimately sequestered by silicate weathering may be processed through an area corresponding to only ~ 1% of the exorheic drainage area worldwide. [ABSTRACT FROM AUTHOR]

We investigated grain size, clay mineralogy, elemental geochemistry, organic composition, and AMS 14 C dating ages in Core KX12-3 from the middle Okinawa Trough in order to better understand the sediment provenances and transport processes and also the forcing mechanisms behind their variations over the last 18.5 ky. The geochemical–mineralogical indices reveal three notable phases of change in the sediment provenance of the core, which are related to the development of the Kuroshio Current coupled with sea-level fluctuations, the position shift of the mouths of large rivers, the magnitude of tidal bottom stress, and the East Asian monsoon intensity. The sea-level lowstand deposits of Interval 1 (18.5–9.3 ka) formed from mixed sediments originating mostly from Chinese rivers (the paleo-Huanghe and the paleo-Changjiang) as well as from materials eroded from seafloor by the strong tidal stress. Thereafter during Interval 2 (9.3–8.7 ka), a significant sea-level rise, the moderate tidal bottom stress, and a gradual landward retreat of river mouths led to obviously decreased sediment supplies from both seafloor erosion and mainland China rivers (especially the paleo-Huanghe) into to the study area. After this transitional period, the dominant sediment provenance during the mid-to-late Holocene (Interval 3) changed to the Changjiang and seafloor erosion, resulting in lower detrital linear sedimentation rate and finer grain size. At the same time, some fine-grained materials from Taiwan may have been transported northward to the study area by the Kuroshio Current, as evidenced by higher values of chlorite/kaolinite ratio and chemical index of illite, and lower TOC/TN values. In addition, a prominent decline in chlorite/kaolinite values that occurred at 5.0–3.5 ka may have been linked to a suppression of the Kuroshio Current, probably related to the Pulleniatina minimum event and/or the late Holocene Neoglacial cold event commonly found in the northwestern Pacific. [ABSTRACT FROM AUTHOR]

For this study, elemental and Sr–Nd isotopic compositions of AMS 14 C age-dated core sediments from the northern Okinawa Trough were investigated to reconstruct sediment provenance and transport processes over the last 22.3 ka and further to trace the forcing mechanisms behind the provenance changes. The results clearly showed that large compositional variations of these elements and isotopes occur in deposition, suggesting three-phases of changes in sediment source: paleo-Huanghe (Unit 3, 22.3–14.8 ka), East China Sea shelf-derived (Unit 2, 14.8–7.3 ka), and Taiwan-derived detritus stages (Unit 1, < 7.3 ka). Such provenance changes since the last glacial maximum may be closely correlated to sea-level fluctuation, the evolution of Tsushima Warm Current, as well as East Asian monsoonal climatic variation. At 22.3–14.8 ka, the paleo-Huanghe mouth was situated close to the study area, thus dominating sedimentation therein, especially during stronger winter monsoon periods. At the beginning of Unit 2 (14.8–12.8 ka), rapid sea-level rise and significant retreat of the river mouth overwhelmed enhanced continental weathering, leading to less detrital sediment supply from the paleo-Huanghe to the study area. Subsequently, the East China Sea shelf-derived matter dominated detrital deposition therein from 12.8 to 7.3 ka. Since 7.3 ka, the fully evolved Tsushima Warm Current has transported some detrital particles from Taiwan to the study area, especially during the strengthening period at 7.3–5.1 ka. A prominent decline in Taiwan-sourced matter supply at 5.1–2.8 ka may have been caused by suppression of the Tsushima Warm Current, possibly associated with the Pulleniatina minimum event. [ABSTRACT FROM AUTHOR]

In this study, Holocene changes in the riverine, eolian, and erosional supplies to the eastern part of the central Yellow Sea (YS) and their forcing mechanisms were determined on the basis of multiple mineralogical and geochemical indices of three age-dated piston cores from the central Yellow Sea mud (CYSM) deposition. The core records of the indices, including clay minerals, rare earth element fractionation parameters, and conservative trace elements, revealed abrupt changes in the sediment sources, especially ∼9.0 and 4.8 ka. The late last deglaciation and early Holocene sediments (Units 3 and 4, ∼14.1 to ∼9.0 ka) most likely originated from the paleo-Huanghe and the sea bed erosion, together with some contribution from the paleo-Changjiang Shoal sediments that extended northeastward into the YS. After that period, the dominant sediment source gradually changed to the Changjiang during the middle Holocene (∼9.0–4.8 ka, Unit 2), while the supplies from Huanghe and sea bed erosion to the south YS decreased. In the last 4.8 ka (Unit 1), the CYSM largely received Changjiang-derived sediments. Besides, some clay-sized particulates from the Huanghe, sea bed erosion, and Korea rivers might be transported to the CYSM during Unit 1. Possible mechanisms behind such changes in the riverine and erosional sediment sources and contributions include position shifts of river mouths, tidal stress evolutions, shelf sea-level fluctuations, East Asian monsoon climate changes, and the development of the YSWC and coastal circulation systems. [ABSTRACT FROM AUTHOR]

Despite the well-reconstructed paleoceanography of the late Quaternary deposits in the East (Japan) Sea (ES), provenances of terrigenous sediments and a comprehensive interpretation of their variations since the Last Glacial Maximum remain unclear, especially in regard to the mainland China- and Taiwan-derived matter. Grain size, conservative trace elements, rare earth elements (REEs), Nd isotope, and clay mineralogy of core sediments from the Ulleung Basin of the ES were investigated for better understanding of detrital sediment provenance and transport process and then their forcing mechanisms over the last 21 kyr. Geochemical–mineralogical multi-indices in this study showed notable three-phase changes in sediment provenance, which can be closely related to sea-level fluctuation, development of the Tsushima Warm Current as well as intermittent influence from the East Asian summer monsoon climate evolution. During Unit 1 (21.1–8.4 kyr BP) when the Tsushima Warm Current was absent in the ES, the paleo-Changjiang and the paleo-Huanghe mouth might be situated close to the study area and thus mainland China could have played major role in the southwestern Ulleung Basin sedimentation. In particular, the formation of rhythmic dark-colored alternation in Unit 1 is possibly attributable to the pulse of paleo-Huanghe discharge associated with centurial- to millennial-scale variability in the East Asian summer monsoon. In Unit 2 (8.4–7.2 kyr BP), these river mouths gradually retreated to their present positions with global sea-level rise, leading to decreasing terrigenous sediment supply from mainland China to the study area. Since 7.2 kyr BP (Unit 3), sedimentation in the Ulleung Basin should still be mainly derived from mainland China. Meanwhile, increasing chlorite/kaolinite ratio but decreasing ε Nd value revealed that terrigenous matter from Taiwan might have been limitedly transported northward to the study area by the fully evolved Tsushima Warm Current. A prominent decline in chlorite/kaolinite ratio, together with contrast change on ε Nd value, centered at around 2.9 kyr BP (3.3–2.4 kyr BP) may have been caused by the Tsushima Warm Current suppression, possibly related to the Pulleniatina minimum event popularly found in the study area and nearby seas. [ABSTRACT FROM AUTHOR]

The Oceanic Anoxic Event 2 (OAE 2) represents one of the most profound global environmental disturbances of the Mesozoic Era, which was associated with a positive carbon isotope excursion due to widespread organic carbon burial. However, the character, evolutionary history, and exact driving mechanisms of OAE 2 are still much debated, exacerbated by the lack of records from climate-sensitive southern high latitudes. Here we present a multi-proxy record of a stratigraphically continuous succession spanning the late Cenomanian to early Turonian at the International Ocean Discovery Program Site U1516 in the Mentelle Basin off southwest Australia, which was located at southern high latitudes (~ 60–62°S) during the Late Cretaceous. Sedimentary records at Site U1516 allow the first detailed insights into source-to-sink processes in the Mentelle Basin and associated paleoenvironmental reconstruction in the southern Indian Ocean during OAE 2. Rare earth element abundances and clay-bound neodymium isotopes of the siliciclastic sediment fractions indicate that southwest Australia was the main detrital source of sediment at Site U1516 during OAE 2, with volcanogenic sediments representing only a minor component. A major provenance shift is observed across OAE 2, indicating an increased sediment contribution from distant sources (i.e., Yilgarn Craton and Albany-Fraser Orogen) relative to proximal sources (i.e., Perth Basin and Leeuwin Block) in southwest Australia, interpreted as reflecting a major reorganization of the drainage system due to enhanced fluvial runoff. Based on these findings, we infer that the OAE 2 interval showing the most prominent δ13C excursion was associated with an intensification of the hydrological cycle in the high-latitude southern hemisphere, with potential impacts on regional ocean chemistry and marine productivity. In particular, we suggest that enhanced terrigenous input and riverine nutrient export likely played a key role in controlling siliceous productivity at nearby ocean margins. As a consequence, the intense burial of organic matter (i.e., black shale) at Site U1516, which occurred episodically throughout OAE 2, possibly resulted from the combination of enhanced riverine-driven marine productivity and increased burial efficiency associated with the development of anoxic/euxinic bottom water conditions. • First detailed investigation of the source-to-sink process of the Mentelle Basin during OAE 2. • Geochemical records indicate dominant detrital contribution from Southwest Australia during OAE 2. • Enhanced hydrological cycle at southern high latitudes occurred during the interval with the most prominent δ13C excursion. • Multi-proxy records suggest a tight link between oceanic and continental changes during OAE 2. [ABSTRACT FROM AUTHOR]

Based on a δO chronology, rare earth elements (REE) and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and investigate quantitative changes in the Asian eolian input to the study area over the last 700 ka. Among the competing processes that might affect REE compositions, sediment provenance is the most important one. Provenance analysis suggests that the study sediments have two provenance end-members; local volcanic sources are dominant, and eolian dust from the Asian continent has a smaller contribution. During glacial periods, eolian input to the western Philippine Sea was enhanced. In contrast, material supply from local volcanics increased during interglacial periods. Changes in eolian input to the study area were probably related to the strength of the East Asian winter monsoon (EAWM) as well as aridity in the Asian continent on an orbital time scale, and were partly influenced by local control factors on shorter time scales. Therefore, we propose that the present study expands the application of the REE-based method for quantitatively estimating the eolian component from the mid-latitude northern Pacific to the low-latitude western Pacific. Additionally, the study preliminarily confirms the influence of EAWM-transported eolian material on sedimentation in the western Philippine Sea since 700 ka. [ABSTRACT FROM AUTHOR]

Abstract: Provenances of clay-sized terrigenous sediments and a comprehensive interpretation of their high-resolution variations in the northern Okinawa Trough since the late last glaciation remain unclear, especially in regard to the Huanghe- and Taiwan-derived matter. Grain size, clay mineralogy, typical elemental ratio, oxygen isotope, and AMS 14C dating of core PC-1 in the northern Okinawa Trough were investigated to trace clay-sized sediment provenance and transport process and thus to recover their forcing mechanisms over the last 22kyr. Variations in linear sedimentation rate, grain size, δ18O, Ti/Ca ratio, and clay minerals can be clearly divided into three distinct intervals, consistent with changes in sediment provenance that can be close related to sea-level fluctuation, evolution of the Tsushima Warm Current as well as influence from the East Asian monsoon climate evolution. During the late last glaciation period (Interval 1, 22–16kyrBP) when the Tsushima Warm Current was absent in the East China Sea, the paleo-Huanghe mouth was situated close to the study area and thus the paleo-Huanghe could have played major role in sedimentation therein. In Interval 2 (16–7.3kyrBP), global sea-level rise led to gradually retreating of the paleo-Huanghe mouth and thus decreasing terrigenous sediment supply from it to the study area. Since 7.3kyrBP (Interval 3), some clay minerals from Taiwan might have been transported northward to the study area by the fully evolved Tsushima Warm Current, characterized by higher chlorite/kaolinite ratios. In contrast, the decreasing influence of the Huanghe-derived sediments during the strengthening of the Tsushima Warm Current periods was probably caused by the blocking effect of the Tsushima Warm Current. Particularly, chlorite/kaolinite ratio and smectite content in the Okinawa Trough sediment might be good proxies for indicating the Tsushima Warm Current-related sedimentary environment. [Copyright &y& Elsevier]

To synthetically realize the character of major-element compositions as well as its significance for provenance and paleoenvironment recorded in core sediments of the West Philippine Sea over the last 700 ka, grain size and major elements of 221 bulk sediments, together with major-element compositions in the detrital phase of 16 typical samples, in core MD06-3047 collected from the Benham Rise were analyzed. Both discrimination plot and R-mode factor analysis indicate that vertical changes of major elements are mainly controlled by the sedimentation of nearby volcanic matter and the eolian dust input, whereas influences from marine biologic deposition and hydrothermal activity are minor. In particular, AlO and KO are representative of an eolian dust factor. The variation in the eolian dust factor score is characterized by the obviously glacial-interglacial periodicity and can be well compared with the paleotemperature record of the Antarctic ice core and the evolution of the East Asian winter monsoon (EAWM) recorded in the Chinese loess sequence, and then offers a new proxy for the evolution history of eolian dust input into the study area that is controlled by the EAWM intensity and aridity in the continental source regions of atmospheric dust. [ABSTRACT FROM AUTHOR]

Abstract: Clay mineral assemblage of the core MD06-3047 in the western Philippine Sea has been used to trace sediment provenance and transport process and thus to constrain the East Asian monsoon evolution as well as its forcing mechanism over the past 700kyr. Clay minerals mainly consist of smectite (61%) and illite (23%), with minor chlorite (10%) and kaolinite (6%). Provenance analyses suggest that the smectite originates predominantly from the alteration of nearby Luzon volcanic rocks. Illite is primarily derived from the Asian continent with eolian origin. Illite contents show strong glacial/interglacial cyclicity as constrained by oxygen isotope stratigraphy. Variations of illite contents are ultimately controlled by the East Asian monsoon evolution, characterized by higher illite values during glacials with relatively stronger East Asian winter monsoon but weaker East Asian summer monsoon. During interglacials, enhanced East Asian summer monsoon and rainfall could produce more smectite with poor crystallinity from Luzon to the study core. Spectral analyses of illite content and smectite crystallinity display a strong periodicity at 100kyr for the East Asian winter monsoon and 100kyr, 30kyr, and 23kyr periodicities for the East Asian summer monsoon, respectively, suggesting the unique forcing processes of the East Asian winter monsoon from high-latitudes (i.e., ice volume) and the East Asian summer monsoon from both high-latitudes and low-latitudes (i.e., tropical Pacific). [Copyright &y& Elsevier]

Paleoenvironmental changes in the northern Okinawa trough covering the last 25 ka were synthetically reconstructed using REE and organic carbon indices of core CSH1. Variations of these parameters revealed three distinct intervals of major sediment provenance changes that can be related to sea-level fluctuation and Tsushima Warm Current evolution. Interval 1 (16-24.7 ka BP) is characterized by dominantly fluvial discharge from the Changjiang (Yangtze River) and Huanghe (Yellow River) as well as high primary productivity. In Interval 2 (7.3-16 ka BP), the Changjiang and Huanghe mouths regressed with sea-level rising. The newly formed Tsushima Warm Current could carry some sediment loads of Taiwan to the study core, especially during its late phase (7.3-8.2 ka BP). Modern oceanographic conditions were finally established since the beginning of Interval 3, leading to more terrigenous contribution from Taiwan, whereas low sea-surface productivity in the study area. [ABSTRACT FROM AUTHOR]

Abstract: A millennial-scale paleoceanographic record of the Ulleung Basin in the southern part of the East (Japan) Sea (ES) for the last 20,000years was reconstructed based on variations in the element compositions of core sediment. Most of the elements showed relatively wide content ranges throughout the core, largely because of different sediment types, their grain size spectra, biological components, and geochemical conditions (i.e., redox conditions). In particular, biogenic components (Ca, Sr, Ba, and CaCO3) and some minor elements (Cu, Mn, Mo, U, Cd, Zn, and V) revealed three distinct intervals of major paleoceanographic changes. Interval 1 (∼18–9.3kyr BP) is characterized by a rhythmic alternation of dark- and light-colored sediment bands. Distinctive differences in the abundance of organic carbon, carbonate, and redox-elements between the dark- and light-colored-sediment layers are probably attributable to especially those associated with bottom-water redox variations combined with the enhanced primary productivity and water stratification in the Ulleung Basin. These alternations perhaps reflect fluctuations in paleo-discharge from Chinese and/or Korean rivers during the last deglaciation. From a global perspective, the repetition of dark sapropelic sediment layers suggests a possible teleconnection between oceanographic change and development of the East Asian summer monsoon and consequent fluctuations in fluvial discharge from Korean and Chinese rivers to the East Sea basin. In Interval 2 (9.3–6.5kyr BP), a remarkable increase in the concentrations of organic carbon and redox elements is probably linked to the intrusion of the warm/saline Tsushima Current to the basin, which would have enhanced ventilation and upwelling of nutrient-rich sub-surface waters. In parallel, a pronounced decrease in carbonate content indicates extensive carbonate dissolution due to the consumption of large amounts of free pore-water oxygen in surface sediments that would have accompanied by the decomposition of organic matter. In Interval 3 (6.5kyr BP–Present), most geochemical parameters are relatively constant, suggesting little changes in paleoenvironments; these observations indicate that modern oceanographic conditions were established in the East Sea at about 6.5kyr BP. In particular, a prominent decline in carbonate contents centered at around 3–4kyr BP appears to have been caused by a decrease in primary productivity in association with a suppression of the warm Kuroshio Current, rather than by geochemical processes. [Copyright &y& Elsevier]

Rare earth elements (REEs) of 91 fine-grained bottom sediment samples from five major rivers in Korea (the Han, Keum, and Yeongsan) and China (the Changjiang and Huanghe) were studied to investigate their potential as source indicator for Yellow Sea shelf sediments, this being the first synthetic report on REE trends for bottom sediments of these rivers. The results show distinct differences in REE contents and their upper continental crust (UCC)-normalized patterns: compared to heavy rare earth elements (HREEs), light rare earth elements (LREEs) are highly enriched in Korean river sediments, in contrast to Chinese river sediments that have a characteristic positive Eu anomaly. This phenomenon is observed also in primary source rocks within the river catchments. This suggests that source rock composition is the primary control on the REE signatures of these river sediments, due largely to variations in the levels of chlorite and monazite, which are more abundant in Korean bottom river sediments. Systematic variations in ΣLREE/ΣHREE ratios, and in (La/Yb)–(Gd/Yb)UCC but also (La/Lu)–(La/Y)UCC and (La/Y)–(Gd/Lu)UCC relations have the greatest discriminatory power. These findings are consistent with, but considerably expand on the limited datasets available to date for suspended sediments. Evidently, the REE fingerprints of these river sediments can serve as a useful diagnostic tool for tracing the provenance of sediments in the Yellow Sea, and for reconstructing their dispersal patterns and the circulation system of the modern shelf, as well as the paleoenvironmental record of this and adjoining marginal seas. [ABSTRACT FROM AUTHOR]

Based upon analyses of grain-size, rare earth element (REE) compositions, elemental occurrence phases of REE, and U-series isotopic dating, the sediment characteristics and material sources of the study area were examined for the recently formed deep-sea clays in the eastern Philippine Sea. The analytical results are summarized as follows. (1) Low accumulation rate, poor sorting and roundness, and high contents of grains coarser than fine silt indicate relatively low sediment input, with localized material source without long distance transport. (2) The REE Contents are relatively high. Shale-normalized patterns of REE indicate weak enrichment in heavy REE (HREE), Ce-passive anomaly, and Eu-positive anomaly. (3) Elemental occurrence phases of REE between the sediments with and without crust are similar. REE mainly concentrate in residual phase and then in ferromanganese oxide phase. The light REE (LREE) enrichment, Ce-positive anomaly, and Eu-positive anomaly occur in residual phase. Ferromanganese oxide phase shows the characteristics of relatively high HREE content and Ce-passive anomaly. (4) There are differences in each above mentioned aspect between the sediments with and without ferromanganese crust. (5) Synthesizing the above characteristics and source discriminant analysis, the study sediments are deduced to mainly result from the alteration of local and nearby volcanic materials. Continental materials transported by wind and/or river (ocean) flows also have minor contributions. [ABSTRACT FROM AUTHOR]

Changes in terrigenous organic matter (OM) input, productivity and the associated bottom-water redox conditions, together with forcing mechanisms and global carbon cycle implications of such variations, on the western margin of the Western Pacific Warm Pool (WPWP) during the Quaternary remain controversial. In this study, we reconstructed the hydrological dynamics, terrigenous OM input, productivity, and deep-sea redox conditions using one core from the continental slope of the Philippine Sea. The new data were integrated with published proxies from the same core and two additional cores from the abyssal Philippine Sea. The results exhibited noticeable variations in the abovementioned indicators, in correspondence to changes in the supply of terrigenous material. The continental slope deposition featured signals of strong physical erosion and chemical weathering of unconsolidated sediments on the exposed continental shelf during the Quaternary sea-level lowstands, which significantly contributed to increased terrigenous OM input and productivity and, in turn, decreased bottom-water oxygenation and atmospheric CO 2 concentrations. In the abyssal Philippine Sea, increased Asian dust-driven OM input and productivity also acted as a sink of atmospheric CO 2 during sea-level lowstands. Analysis of the data suggested that the enhanced terrigenous OM input and biological pump and thus the decreased dissolved oxygen level of the bottom water on the western margin of the WPWP played important roles in modifying the global carbon cycle during sea-level lowstands. In contrast, the influence of hydrological dynamics on terrigenous OM input, productivity, and redox conditions therein during the Quaternary was limited. • First integrative OM and productivity study on the western margin of the WPWP. • Enhanced terrigenous OM input and productivity occurred during sea-level lowstands. • The studied area was an important sink for atmospheric CO 2 during sea-level lowstands. [ABSTRACT FROM AUTHOR]

We analyzed rare earth elements (REEs) and Sr Nd isotope compositions of siliciclastic components in a sediment core from the middle Okinawa Trough (OT), to elucidate spatiotemporal variations in the sediment provenance, and their underlying mechanisms for the last 20 ky. Our results show that the trough deposits were characterized by different proportions of Changjiang- and Taiwan-derived (especially, the western rivers) sediments over time, from which we infer dramatic changes in sea-level, intensity of the Kuroshio Current (KC) inflow, and the East Asian monsoon since the last glacial maximum (LGM). In contrast to previous studies, the sea-level lowstand proximity of the paleo-Changjiang to the middle OT, and the contemporaneous enhancement of the East Asian winter monsoon (EAWM) may have played pivotal roles in supplying terrigenous inputs and forming middle OT deposits during the last glacial period, whereas the paleo-Huanghe was of lesser importance. After the early Holocene (especially the late Holocene cold period between ~4.8 and ~2.7 cal ky BP), a remarkable shift in the combined records of REEs and Nd isotopes reveals a causal link between variations in the Taiwan source and the KC inflow, coupled with climate changes in the East China Sea (ECS). This study suggests that Sr Nd isotope compositions and REEs are useful proxies for understanding the links between river development and paleoenvironmental/paleoclimatic changes in East Asian marginal regions. • Sr Nd isotopic records provide new insights into the sediment source in Okinawa Trough (OT). • Changjiang has played a leading role in forming the middle OT deposits during the last glacial period. • Taiwan-sourced sediments in the OT deposits are linked to Kuroshio/Taiwan Warm Current dynamics. • Our study provides that the comprehensive accumulation history of OT deposits over the last 20 ky. [ABSTRACT FROM AUTHOR]

Introduction: Inner retinal dimples (IRDs) are frequently detected after internal limiting membrane (ILM) peeling. However, the distribution of IRDs and its effect on postoperative visual function remain unclear. We aim to quantify the distribution of IRDs after ILM peeling in different macular diseases and analyze its influence on postoperative visual function. Methods: We retrospectively reviewed patients undergoing vitrectomy with ILM peeling and followed up until 12 months in our center. The distribution of IRDs were quantitatively determined using optical coherence tomography (OCT) and OCT angiography in a different sector of Early Treatment Diabetic Retinopathy Study grid. Visual function was evaluated by retinal sensitivity (RS) using microperimetry. Spearman correlation was performed between RS and IRDs within the same sectors. Multivariate linear regression analysis was performed to analyze the association between baseline characteristics and IRDs. Results: A total of 43 idiopathic macular hole (iMH) cases, 56 idiopathic epiretinal membrane (iERM) cases and 42 myopic foveoschisis (mFS) cases were included. IRDs increased gradually at ILM-peeled area, interrupting ganglion cell layer. Most IRDs were observed in temporal sector. A negative correlation was depicted between the increase of IRDs and the progress of RS at both perifovea and parafovea in iERM, but only at perifovea in iMH. No significant correlation between the change of IRDs and RS was found in mFS. Multivariable linear regression model showed that preoperative axial length was significantly associated with postoperative IRDs in all patients. Conclusions: IRDs distributed mostly at temporal sector after ILM peeling, interrupting ganglion cell layer. IRD progression may influence postoperative RS only in iMH and iERM. Ophthalmologists may avoid temporal sector especially in eyes with normal axial length or strong ILM–ERM adherence. [ABSTRACT FROM AUTHOR]

As the second largest dust source on the globe, the tectonic and climatic evolution of continental Asia has an important impact on regional and global climate change. The West Pacific is the main sediment sink for eolian dust transported eastward from the Asian interior. Clay minerals, as the major fine-grained weathering products of continental rocks, can be readily transported by wind or currents over long distances and thus have been widely used in the reconstruction of paleoclimate and weathering history. However, the overall evolutionary tendency and response mechanism of clay mineral records over large spatial and long timescales across Asia remain unclear. Here, two continuous and high-resolution clay mineral records since 30 Ma were reconstructed from sediments at Deep Sea Drilling Program (DSDP) Sites 292 and 296 in the Philippine Sea. Clay minerals and Sr-Nd isotope compositions were used to constrain provenance and reconstruct the drying history of the dust source region since the Oligocene. The results show that the clay-sized detrital sediments in the Philippine Sea are a mixture of Asian eolian dust and volcanic materials from the West Pacific arcs. Based on the clay mineral compositions and eolian flux, we reveal that the Asian interior has been continuously drying since the late Oligocene and that stepwise enhanced aridification occurred at approximately 20, 14, 7, and 3 Ma. Compared with other regions of the world, the relative contents of illite and chlorite increased more dramatically in Asia during the late Cenozoic, and the inconsistency became more obvious at approximately 20 Ma. Since 3 Ma, illite and chlorite have increased consistently across the globe. Combined with the Asian tectonic and climatic history, we suggest that the increase in illite and chlorite from Asia between 20 and 3 Ma was mainly in response to the uplift of the Himalayan-Tibetan Plateau, whereas after 3 Ma, it was primarily controlled by global cooling driven by the expansion of the Arctic ice sheet. [ABSTRACT FROM AUTHOR]

The Oceanic Anoxic Event 2 (OAE 2; ca. ∼94 Ma) represents one of the most extreme carbon cycle perturbations of the Phanerozoic, which coincided with major environmental and climate reorganization in both terrestrial and marine realms. Chemical weathering of continental silicate rocks is thought to have played a crucial role during OAE 2, through enhanced release of bio-essential nutrients to the ocean, promoting high rates of marine primary production and organic carbon burial, but also due to its effect on atmospheric CO 2 drawdown, which altogether possibly drove the OAE 2 termination. Yet, the evolution of continental chemical weathering during OAE 2 remains poorly defined, especially in high-latitude regions. In this study, we present a combined hafnium-neodymium isotope investigation of the clay-size detrital fraction (△ ε Hfclay) of late Cenomanian to early Turonian sediments from the southwest Australian margin, at a site (International Ocean Discovery Program U1516) located in the southern high latitudes (∼62°S) during the late Cretaceous. The reliability of △ ε Hfclay as a proxy for continental chemical weathering in ancient anoxic marine sediments was assessed by analyzing a suite of samples retrieved from methanogenic sediments experiencing marine silicate weathering at ocean margins, suggesting negligible effect of reverse weathering on hafnium-neodymium isotope compositions. At Site U1516, the early stage of OAE 2 was characterized by relatively low △ ε Hfclay values (−5.9 ± 2), typical of reduced chemical weathering in nearby continental regions. At the onset of the most prominent carbon isotope excursion, an abrupt decrease in △ ε Hfclay points towards accelerated export of poorly weathered sediments resulting from the abrupt reactivation of river systems in southwest Australia. This period was followed by a pronounced △ ε Hfclay shift towards positive values, indicative of intensifying chemical weathering conditions during the OAE 2 interval showing the highest δ 13 C anomaly. Based on these results, we posit that enhanced hydrological cycle, most likely caused by a southward shift of the westerlies, led to a large increase in weatherability at southern high latitudes during peak OAE 2 warmth. This finding provides empirical support for the potential role played by high-latitude weathering systems in driving the termination of OAE 2, via weathering-driven consumption of atmospheric CO 2 and accelerated riverine fluxes of nutrients leading to enhanced organic carbon burial in marine sediments. • Combined Nd-Hf isotopes as a proxy for continental weathering during OAE 2. • Negligible influence of reverse weathering on Hf-Nd isotopes in marine clays. • Intensifying weathering and river discharge in SW Australia during peak OAE 2 warmth. • Southward shift of westerlies drove enhanced weatherability in southern high-latitude regions. [ABSTRACT FROM AUTHOR]

The Eocene was a critical period of global plate reorganization and it also saw the Earth's climate transition from the warmhouse state to the coolhouse state. Reconstructing the Eocene sedimentary history in the climate-sensitive Southern Ocean is important for understanding paleoenvironmental changes in response to the accelerated Australia/Antarctica separation and global cooling throughout the middle and late Eocene. Here, we present the first detailed multiproxy record of a continuous sequence from International Ocean Discovery Program (IODP) Site U1514 in the Mentelle Basin off southwestern Australia. Our aim is to reconstruct the sediment provenances and paleoenvironmental evolution in response to the abovementioned climatic and tectonic changes in the mid-high southern latitudes during the Eocene. Provenance analyses based on Sr-Nd isotopes, trace elements, and clay mineral assemblages suggest that Eocene sediments at Site U1514 predominantly originated from the southwestern Australian continent and the Naturaliste Plateau. Sediment provenance variations during the middle Eocene indicate that the onset of fast separation between Australia and Antarctica at 43 Ma caused an increased supply of volcanic materials from the Naturaliste Plateau between 43 and 38 Ma. Terrigenous inputs to the Mentelle Basin during the middle Eocene were primarily controlled by paleoclimate changes rather than tectonic processes because coeval clay mineralogical changes (higher kaolinite/smectite ratio and MAR kaolinite) indicate a period of stronger physical erosion and chemical weathering on the western Australian continent that resulted in increased terrigenous materials delivered to the Mentelle Basin. Our results reveal a 5 Myr-long (43–38 Ma) warming reversal in the southern mid-high latitudes, providing an exception to the generally short-lived (10–100 kyr-long) hyperthermals that interrupted the long-term global cooling throughout the middle to late Eocene. As for the late Eocene (38–37 Ma), tectonic processes related to the sudden acceleration in seafloor spreading in the Tasman Sea led to the exposure of shallower areas, resulting in rapid detritus accumulation at the study site. During the late Eocene (37–34 Ma), major sediment provenance shifted from distal source areas (e.g., the Yilgarn Craton) to relatively proximal sources (e.g., the Leeuwin Block and Perth Basin). We interpret that the regional uplift in southwestern Australia and coeval climate cooling resulted in the diversion and inactivation of large drainage systems, thus blocking the transportation of sediment from distant regions. • First detailed record of the Eocene source-to-sink process in the Mentelle Basin. • The onset of fast Australia/Antarctica separation caused increased volcanic input. • Regional warming led to enhanced chemical weathering in Australia during 43–38 Ma. • Regional uplift and global cooling induced sediment source change during 37–34 Ma. [ABSTRACT FROM AUTHOR]

Analyses of mass accumulation rate (MAR), laser grain-size, clay mineralogy, and Sr Nd isotopic compositions of <2 μm and < 63 μm grain-size fractions have been applied to sediments from the International Ocean Discovery Program (IODP) Site U1456, which span the last 31 ka, in order to constrain (i) past changes in the relative proportions of the fine-grained detrital sediments derived from the Indus River and the Deccan Traps and the dynamics of sediment transport to the Laxmi Basin and (ii) past changes in Indian monsoon rainfall and latitudinal migration of Intertropical Convergence Zone since the last glacial period. Sr and Nd isotopes results combined with clay mineral assemblages suggest that clay-sized sediments at IODP Site U1456 derive mainly from the Indus River (70–90%), followed by a minor contribution from rivers draining the volcanic province of the Deccan Traps (10–30%). During the Last Glacial Maximum, clay mineralogy was dominated by illite and chlorite primarily derived from the highlands of the Indus River basin. The combination of lower temperatures and lower monsoonal rainfall during glacial times led to a reduction of smectite formation rates in the floodplains, while glacial erosion accelerated in the Himalayan and Tibetan highlands leading to the release of large quantities of illite and chlorite minerals into the Arabian Sea. In addition, glacial low sea-level stands allowed a connection between river mouths and the heads of deep-sea channels favoring the southward transfer of sediments to IODP Site U1456 by turbidity currents. Each maximum of the summer insolation curve, associated with a northward shift of the ITCZ and an intensification of summer monsoon rainfall (from 31 to 25 ka BP and from 12 to 8 cal ka BP), was associated with enhanced rainfall in the Indus floodplain which in turn led to an increase in the physical erosion and weathering of plain soils, which were rich in pedogenic minerals (such as smectite), and/or a higher production rate of smectite in the soils of the Indus floodplain. A compilation of three Nd isotopic composition records obtained at sites located on a N-S latitudinal transect in the eastern Arabian Sea have allowed us to establish the impact of sea level variations and latitudinal migration of the ITCZ over time on the sedimentation of the eastern Arabian Sea. • The detrital sediments in the eastern Arabian Sea are mainly sourced from the Indus River and Deccan Traps since 31 cal ka BP. • The climate and sea-level variations forcing of detrital sediments input to the eastern Arabian Sea since 31 cal ka BP. • The shift in river inputs between N-S could be related to a migration of the ITCZ and associated location of the rain belt. [ABSTRACT FROM AUTHOR]

Despite the importance of the westerlies to the global climate system, we still know little about their long‐term evolution and possible orographic controls during the late Cenozoic because of the lack of sedimentary records with precise chronological control. Eolian deposition in the North Pacific preserved past information about the westerlies, the major wind system delivering Asian dust to the Pacific. A continuous, high‐resolution eolian flux record since 23 Ma was reconstructed from sediments at Deep Sea Drilling Project Site 296 in the North Pacific. Combined with dust flux at Ocean Drilling Program Site 1208, variations in their difference indicated a northwards shift of the westerlies during 23‒9 Ma and a relatively stable state since then. We suggest that Tibetan uplift since the early Miocene began to drive the poleward shift of the westerlies until 9 Ma, after which the westerlies remained relatively stable over Asia on million‐year timescales. Plain Language Summary: The Northern Hemisphere Westerly wind is a significant component of planetary‐scale atmospheric circulation and has a large impact on regional and global climate change. Although numerous modern observations and orbital time‐scale studies of the Westerly wind have been conducted, we still know little about its evolution on million‐year time‐scales, which may modulate the overall amplitude of short‐term variations. Eolian deposition in the North Pacific has preserved precious information about the westerlies in the past. A continuous and high resolution eolian flux record dating from 23 Ma was reconstructed from sediments at Deep Sea Drilling Project Site 296 in the Northwest Pacific. Combined with dust records at Ocean Drilling Program Site 1208 to the east, we constrain how the path and strength of the Northern Hemisphere Westerlies have changed since the early Miocene. The two eolian records indicate a northwards shift of the westerlies between 23 and 9 Ma and a relatively stable state since then. We suggest that stepwise uplift of the Tibetan Plateau since at least the early Miocene began to drive the northwards shift of the Northern Hemisphere Westerlies until about 9 Ma, after which the westerlies remained relatively stable over Asia‐North Pacific on million‐year timescales. Key Points: We reconstruct the eolian flux record in the North Pacific since 23 Ma at high resolutionThe Northern Hemisphere Westerlies shifted northward between 23 and 9 Ma and have remained relatively stable since thenTibetan uplift drove the northward shift of Northern Hemisphere Westerlies in the early late Miocene [ABSTRACT FROM AUTHOR]

The sediment grain-size effect (GSE), a fundamental factor relevant to the interpretation of elemental concentrations and isotopic compositions, has been normalized using conservative elements such as aluminum (Al), cesium (Cs), and lithium (Li) (C ( Al , Cs , Li ) ), which serve as proxies for the natural metal-controlling variables of grain size, mineralogy, and organic matter. However, a secondary GSE reportedly remains even after compensation by the Al-normalization procedure, particularly for the concentrations of transition metals (C T.M ). This secondary effect also occurred in the C ( Li , Cs ) /C Al ratios of the Korean coastal sediments examined in this study. The primary and secondary GSEs on Cs and Li concentrations can be explained by the quartz-dilution effect and the Cs- and Li-incorporation effect of phyllosilicate minerals, respectively, based on a model involving three component end-members: a Cs- and Li-free sand-dominated sediment component consisting mostly of quartz and feldspar, a Cs- and Li-bearing silt-dominated component of mica, and a Cs- and Li-enriched clay-dominated component of illite. Although the primary and secondary GSEs on the concentrations of transition metals (particularly Cu and Ni) in coastal sediments might be normalized by dividing the metal concentrations by the square of the Al concentration (C T.M . /(C Al ) 2 ), the GSEs can also be normalized by dividing the concentrations by the exact Cs (or Li) concentration (C T.M . /C Cs ). [ABSTRACT FROM AUTHOR]

To obtain a better understanding of the source compositions of the river sediments around the Yellow Sea and their relationship with source rocks, elements and strontium-neodymium (Sr–Nd) isotopes of different grain-sizes (silt and clay populations) and chemical (labile and residual phases) fractionations in riverine sediments were studied extensively. These results clearly revealed a systematic compositional disparity between Korean river (KR) and Chinese river (CR) sediments, especially in the residual (detrital) fraction. The geochemical dissimilarity between these might reflect inherited signatures of their source rocks but with minor control from chemical weathering. In particular, the remarkable enrichment of some elements (iron (Fe) and magnesium (Mg)) and the behavior of large ion lithophile elements (e.g., barium (Ba), potassium (K) and Sr) during weathering as well as less-radiogenic Sr isotopic compositions implies that CR sediments might be weathering products of relatively more mafic rocks, with abundant ferromagnesian and plagioclase feldspar minerals, compared with KR sediments derived from silicic granites with relatively higher quartz and potassium feldspar contents. This different petrological rationale is clearly evident in an A–CN–K diagram, which estimated the source rock of CR sediments as granodioritic, a composition that reflects accurately the average composition of weathered continental crust in China. The recognition of such geochemical systematics in two river sediments, especially in grain-size and chemically partitioned data, may contribute to the establishment of provenance tracers for the Yellow Sea and East China Sea sediments with multi-sources as well the dust deposition in the western Pacific. [ABSTRACT FROM AUTHOR]

Element concentrations ( C element ) of the sediments in the diverse Korean coastal environments were constrained strongly by the grain-size effect (GSE), especially after compensation for metal-free carbonate and organic material contents. However, the GSE in some elements (especially metallic elements) was not completely offset by conventional Al-normalization ( C element / C Al ratio), and further the best-fit regression lines between the concentrations of Al and elements may not be linear, but instead curved, and also cannot pass through the origin point (0, 0). The results suggest the presence of conventional GSE (primary GSE) as well as another GSE (i.e., secondary GSE), which was well supported by the factor analysis for the variable of C element / C Al ratios. Such primary and secondary GSEs are likely caused by physical and chemical processes, respectively, such as the quartz-dilution effect by metal-free, coarse-grained sediments and diagenetic reactions in organic-rich, fine-grained sediments. Furthermore, these GSEs in Korean coastal sediments can be quantitatively normalized by a quadratic equation: C element = a 0 · C Al + a 1 · ( C Al ) 2 , where a 0 and a 1 are constants for the primary and the secondary GSEs, respectively. [ABSTRACT FROM AUTHOR]

Reconstructing sedimentary redox history provides valuable insights into for understanding of paleoceanographic/paleoclimatic changes in the climatically sensitive Southern Ocean. However, our comprehension of the spatial variations in historical redox changes and the driving forces in the Southern Ocean, especially the Antarctic Zone, remains incomplete. Here, we present detailed sedimentary records of the redox state (i.e., sulfur isotopes), bottom-water oxygenation conditions (i.e., redox-sensitive metals), export production (i.e., 230Th-normalized biogenic opal and barium), and carbon burial flux over the last ∼35 kyr in the Protector Basin, the deepest basin of the southern Scotia Sea. The studied sediment record in this basin reveals significant variations in geochemical redox proxies throughout the glacial (MIS 2)–interglacial (MIS 1) period, featuring a significant 34S depletion of up to ∼40‰ relative to seawater sulfate and a noticeable increase in ER Mo /ER U ratio in interglacial sediments. These findings highlight a significant shift in bottom-water and/or sediment oxygenation from glacial oxic to interglacial anoxic/euxinic conditions, primarily driven by climate-induced changes in biogenic productivity, rather than the deep circulation and ventilation dynamics previously emphasized in the Antarctic Zone. Signs of the climate-driven redox change are also evident in two millennial-scale cold events (∼9–8 ka and ∼3–2 ka), marked by sudden shifts toward oxic conditions. Importantly, our results reveal a contrasting scenario to previous observations in the glacial–interglacial redox history within the Antarctic Zone, signifying spatial disparity in bottom-water and sediment redox chemistry. • Sedimentary δ34S and metals records reveal dramatic redox changes in the Antarctic Zone. • Results highlight a glacial (oxic)-to-interglacial (anoxic/sulfidic) change, with millennial-scale variations. • Redox variability in the Antarctic Zone is closely linked to climate-driven productivity changes. • A regional disparity in the glacial–interglacial redox change within the AZ region was observed. [ABSTRACT FROM AUTHOR]

Abstract: Authigenic carbonates were sampled in methane-enriched piston core sediments collected from gas venting sites on the western continental slope of the Ulleung Basin, East Sea of Korea. Multidisciplinary investigations on these carbonates, including the scanning electronic microscope (SEM) observations and mineralogical-geochemical compositions, were carried out to identify the carbon and oxygen sources and the forming mechanism of these carbonates. The authigenic carbonates from the study area correspond to semi-consolidated, compact concretions or nodules ranging from 2 to 9cm in size. X-ray diffraction and electron microprobe analyses showed that most of the sampled carbonate concretions were composed of almost purely authigenic high-Mg calcite (10.7–14.3mol% MgCO3). Characteristically, microbial structures such as filaments and rods, which were probably associated with the authigenic minerals, were abundantly observed within the carbonate matrix. The carbonates were strongly depleted in δ 13C (−33.85‰ to −39.53‰ Peedee Belemnite (PDB)) and were enriched in δ 18O (5.16–5.60‰ PDB), indicating that the primary source of carbon is mainly derived from the anaerobic oxidation of methane. Such methane probably originated from the destabilization of the underlying gas hydrates as strongly supporting from the enriched 18O levels. Furthermore, the strongly depleted δ 13C values (−60.7‰ to −61.6‰ PDB) of the sediment void gases demonstrate that the majority of the gas venting at the Ulleung Basin is microbial methane by CO2 reduction. This study provides another example for the formation mechanism of methane-derived authigenic carbonates associated with gas-hydrate decomposition in gas-seeping pockmark environments. [Copyright &y& Elsevier]

• Coastal zoning aids environmental impact assessment. • Sediment textural and geochemical properties are key characters affecting zoning. • This (Ahn et al., 2001) study applies sediment characters to science-based marine spatial planning. • The South Korean coast can be scientifically divided into three zones. The three zones partly coincide with the previous arbitrarily categorized blocks. • A primary factor constraining the zoning in this case study is tidal range. To assess the environmental impacts of offshore wind farming and sea sand mining, coastal areas are zoned on the basis of their natural oceanographic characteristics. Textural and geochemical properties of South Korean coastal sediments, including mean grain size (Mz), CaCO 3 and organic-matter contents, and metal concentrations (Al, K, Ba, rare earth elements, Zr, etc.), were analyzed and categorized in this case study, practically applying common sediment properties for rational zoning of the South Korean coastal environment. Three characteristic zones are scientifically classified in the study area, although four groups of sediment sampling stations were statistically clustered based on their major sediment properties. Zone 1, in the northwestern part of the Korean west coast, is characterized as covered with coarse-grained sediments containing low concentrations of the measured elements under a macro-tidal regime (6.5–9 m), while Zone 3 is characterized by fine-grained sediments with high elemental concentrations under a micro-tidal regime (>3.5 m). Silty Zone 2 sediments appear to be a mixture of sandy Zone 1 and muddy Zone 3 sediments under a meso-tidal regime. The difference in tidal forces among the zones is proposed as a primary constraint of overall sediment textural and geochemical characteristics, while sediment provenance provides subsequent control. Sediment contamination with anthropogenic pollutants is unperceivable in this case study. However, the K and Li concentrations in coarse-grained feldspar and fine-grained illite, respectively, are likely not limited by the tidal flow regime. [ABSTRACT FROM AUTHOR]

Sediment provenance in the Yellow Sea and northern East China Seas (YECSs) has long been a subject of interest, but its quantification is still inconclusive. Here, we present an improved Al Mg regression analysis by refining its methodological approach to strengthen quantification of sediment source-to-sink transports in the YECSs, with focus on its forcing mechanisms during the Holocene. Our quantitative source estimates clearly depict a considerable supply of the Chinese river (CR) sediments (~50%) to the southwestern Korean coastal region, and the Korean river (KR) sediments (30–40%) to the Central Yellow Sea Mud deposit, which accounts for a good balance between the sediment supply and budget of the shelf deposit. Of particular note is an abrupt decline in the CR contributions around 124°E, which indicates that the CR sediments do not directly reach the eastern part of the Yellow Sea blocked by a strong physical boundary. Further, the observed variations in proportions between Huanghe-, Changjiang- and Korean river-derived sediments over the last 15 kyr – notably an abrupt increase of CR contribution since ~7 ka, followed by a sudden drop at ~3–4 ka – exhibit a good correspondence with other mineralogical proxy records. These temporal provenance changes witnessed robust palaeoenvironmental signals which fit to major climatic and oceanographic events linked with sea-level, intensity of the Kuroshio Current inflow and the East Asian monsoon. This study improves understanding of what pathways and sinks exist within the YECS basin, and how rates of sediment supply from adjacent rivers have changed over time. • An improved Al Mg regression analysis for quantifying sediment source in the YECSs is proposed. • Our estimation well defines spatiotemporal sediment source-to-sink dynamics in the sea. • Sedimentary deposits are characterized by different proportions of the sources over the last 15 kyr • This study provides a broader understanding of the present- and paleo-depositional systems of the sea. [ABSTRACT FROM AUTHOR]

We investigate the phased evolution and variation of the South Asian monsoon and resulting weathering intensity and physical erosion in the Himalaya–Karakoram Mountains since late Pliocene time (c. 3.4 Ma) using a comprehensive approach. Neodymium and strontium isotopic compositions and single-grain zircon U–Pb age spectra reveal the sources of the deposits in the east Arabian Sea, and show a combination of sources from the Himalaya and the Karakoram–Kohistan–Ladakh Mountains, with sediments from the Indian Peninsula such as the Deccan Traps or Craton. We interpret shifts in the sediment sources to have been forced by sea-level changes that correlate with South Asian monsoon rainfall variation since late Pliocene time. We collected 908 samples from the International Ocean Discovery Program Hole U1456A, which was drilled in the east Arabian Sea. Time series of hematite content and grain size of the sediments were examined downcore. We found South Asian monsoon precipitation and weathering intensity experienced three phases from late Pliocene time. Lower monsoon precipitation, with a lower variability and strong weathering intensity, occurred during 3.4–2.4 Ma; an increased and more variable South Asian monsoon rainfall, along with strengthened but fluctuating weathering intensity, occurred at 1.8–1.1 Ma; and a reduced rainfall with lower South Asian monsoon precipitation variability and moderate weathering intensity marked the period 1.1–0.1 Ma. Maximum entropy spectral analysis and wavelet transform show that there were orbital-dominated cycles of periods c. 100 and c. 41 ka in these proxy-based time series. We propose that the monsoon, sea level, global temperature and insolation together forced the weathering and erosion in SW Asia. [ABSTRACT FROM AUTHOR]

A 1108.6 m long core was recovered at Site U1457 located on the Indus Fan in the Laxmi Basin of the eastern Arabian Sea during IODP Expedition 355. Shipboard examinations defined five lithologic units (I to V) of the lower Paleocene to Holocene sedimentary sequence. In this study, δ13C values of sedimentary organic matter (SOM) confirm the differentiation of the lithologic units and further divide units III and IV into two subunits (1 and 2). Based on the underlying assumption that the SOM is decided primarily by a mixture of marine and terrestrial origins, δ13CSOM values at Site U1457 provide information on the terrestrial catchment conditions since late Miocene time. Low δ13CSOM values from late Miocene to late Pleistocene times are similar (c. −22.0 ‰) for the most part, reflecting a consistent contribution of terrestrial organic matter from the catchment areas characterized by dominant C3 land plants. Significantly lower δ13CSOM values (c. −24.0 ‰) in Unit III-2 (∼8 to ∼7 Ma) might be due to a greater input of C3 terrestrial organic matter. The increase in δ13CSOM values at ∼7 Ma and the appearance of high δ13CSOM values (c. −18.0 ‰) within Unit III-1 (∼7 to ∼2 Ma) indicate that C4 biomass overwhelmed the terrestrial catchment environment as a result of enhanced terrestrial aridity in the Himalayan foreland. The three-end-member simple mixing model, estimating the relative contributions of SOM from terrestrial C3 and C4 plants and marine phytoplankton, supports our interpretation of the distribution of C3 and C4 land plants in the terrestrial catchment environment. [ABSTRACT FROM AUTHOR]

Abstract Long marine sequences deposited in the Arabian Sea are suitable to study the orbital sensitivity of sediment dynamics from a source-to-sink perspective. The clay mineralogy and Sr Nd isotopic compositions have been analyzed for the detrital fraction of sediments from IODP Site U1457 located in the Laxmi basin, eastern Arabian Sea to constrain the sediment sources and reconstruct a high-resolution record of sediment export to the Indus deep-sea fan over the past 600 kyr. The 87Sr/86Sr ratio (varying from 0.7154 to 0.7255) and εNd (varying from −12.9 to −9.5) imply a mixing of sediments derived from not only the Indus River but also the rivers draining the Deccan Traps. The variations in the smectite/(illite + chlorite) ratio combined with Sr Nd isotopes permit the reconstruction of past changes in the relative proportions of sediments derived from the Indus River (mainly illite, chlorite and kaolinite) and the Deccan Traps (smectite). The wavelet and cross-spectral analyses further reveal that sediment transport to the eastern Arabian Sea since 600 kyr is mainly dominated by sea-level variations in the eccentricity (100-kyr) band, while the Indian summer monsoon might contribute moderately to the precession (23-kyr) band. The εNd and turbidite frequency indicate that more turbidite events are associated with Indus River-sourced sediments at IODP Site U1457 during sea-level lowstands, which might reflect a reconnection of deep-sea channels to the Indus River mouth and/or reworking of previously deposited Indus River sediments located northward. Highlights • First high resolution clay mineral record from IODP Site U1457 since 600 kyr. • Deccan Traps and Indus River are the main sediment sources for the Laxmi basin. • Clay mineralogy variations from IODP Site U1457 were controlled by sea-level variations. • Turbidite events are associated with Indus River-sourced sediments at IODP Site U1457. [ABSTRACT FROM AUTHOR]

Constraining the dissolved neodymium (Nd) cycle in the ocean is paramount for using Nd isotopic composition ( ε Nd ) as a tracer to reconstruct deep-sea paleocirculations or continental weathering on different time scales. Dissolved ε Nd has been measured in seawater samples from six hydrological stations collected along ∼89°E North–South transect in the Bay of Bengal (BoB) in order to assess the impact of seasonal freshwater and sediment discharges from the continental river systems. Seawater samples collected in this study during June 2012 reveal more radiogenic ε Nd (a difference of ∼2 Epsilon units for the upper 2000 m, and ∼0.5 Epsilon unit below 2000 m) and ∼3–8 pmol/kg lower Nd concentrations than the reported values of nearby seawater samples collected in November 2008. These observations are most plausibly explained by a seasonal variations in dissolved Nd concentrations and ε Nd in the BoB, induced by seasonal variations in the freshwater and sediment discharges from the Ganges–Brahmaputra (G–B) river system. However, we cannot entirely exclude the possibility of spatial differences given that the water stations collected in this study are not exactly the same positions collected in November 2008. A two-box model suggests, (1) the particulate Nd inputs from the G–B river system mainly control the seasonal shift of ε Nd observed in the BoB seawater, and (2) a very rapid Nd exchange exists between lithogenic particles and seawater (at least on the scale of a few months). Seasonal changes in seawater ε Nd may also occur in other marginal seas and in the outflows of major rivers, and these need to be taken into account when using the ε Nd proxy in the ocean. [ABSTRACT FROM AUTHOR]

A well-dated, high-resolution sea surface temperature (SST) record based on long chain unsaturated alkenones from a northern Yellow Sea (NYS) sediment core is present in this study. Variations in linear sedimentation rate, alkenone content and SST clearly reveal five distinct stages, consistent with changes in local sea level as well as the evolution of the Yellow Sea Warm Current (YSWC). Before 8.9 cal. kyr BP, the marine transgression might not reach to the northern part of the NYS. A shallow coastal environment was formed from 8.9 to 8.5 cal. kyr BP, with a subsequent fast transgression during 7.8 to 6.5 cal. kyr BP. After 5.8 cal. kyr BP, the NYS was dominated by a relatively constant marine environment. SST records reveal that the YSWC was likely to have started since 7.0 cal. kyr and strengthened progressively in period of 7.0–5.5 cal. kyr BP. After 5.5 cal. kyr BP, the SST elevated about 1.5 °C, which correlated well to salinity changes along the YSWC indicating that the formation time of the modern YSWC was at about 5.5 cal. kyr BP. The SST variation shows a millennial period of ~ 1500-yr and centennial periods of 131-yr and 113-yr. The ~ 1.5 kyr cycle dominated the period of 8.9–5.5 cal. kyr BP, suggesting a tele-connection between the Yellow Sea SST and global climate changes, might through the Kuroshio current. Centennial periods dominated almost all of cold periods recorded in core BY14, implying the signature of solar irradiance cycles by means of the strengthened East Asia Winter Monsoon (EAWM). [ABSTRACT FROM AUTHOR]

The late Quaternary paleoceanography and paleoenvironment of the South China Sea (SCS) have been well reconstructed over the last decade. In contrast, the provenance of the terrigenous sediments that have accumulated in the northwestern continental shelf mud area remains enigmatic. This study investigated the provenance of these sediments and the paleoenvironmental changes archived in Core X2 via the analysis of geochemical elements, grain size, and accelerator mass spectrometry (AMS) 14 C ages. Based on the upper continental crust (UCC)-normalized REE patterns and REE fractionation parameters, southwestern and western Taiwanese rivers and the Pearl River were identified as the main sources of the fine-grained sediment deposited in the northwestern shelf mud area off Hainan Island. This finding further confirms the long-distance transport (> 1000 km) of fine-grained sediment from Taiwanese rivers to the northern SCS shelf and slope. Obvious changes in the grain size and Chemical Index of Alteration (CIA) record occurred at approximately 4.0 cal kyr BP and were likely caused by increased Hainan Island inputs due to sea level changes. [ABSTRACT FROM AUTHOR]

High-resolution sea surface temperature records based on long-chain unsaturated alkenones ( U 37 K ′ -SST) in the south Yellow Sea (YS) during the period of 3500–1300 cal. yr BP were reconstructed in sediment core Z8 from the Shandong mud wedge. The SST records show broad variations between 14.3 and 16.9 °C (15.6 °C on the average), with a high SST phase at 3500-2750 cal. yr BP, a low and intense fluctuating SST period at 2500-2000 cal. yr BP and a sharp cooling period at 1750-1300 cal. yr BP. Superimposed on this trend, five cooling periods occurred in 3360–3250 cal. yr BP, 3150–3050 cal. yr BP, 2750–2650 cal. yr BP, 2350–2150 cal. yr BP, and 1750-1300 cal. yr BP. Variation pattern of the SST records is similar to the fluctuations of the Kuroshio Current (KC), indicating a close relationship between the Yellow Sea Warm Current (YSWC) and the KC. The general U 37 K ′ -SST curve fluctuates with the local air temperature variations. The intensity of the East Asia Winter Monsoon (EAWM) could be a key factor affected the prevailing relationship between the cold coastal current and the warm YSWC, and dominated the SST variation in core site Z8 during 3500–1300 cal. yr BP. Furthermore, our temperature records, within age uncertainty, coincides with the changes of the solar irradiance changes, suggesting a possible link between solar forcing and climate variability. [ABSTRACT FROM AUTHOR]

To geochemically characterize mercury (Hg) in the deep-sea ridge environment, the total concentration, chemical forms (sequential leaching extraction), and isotopic compositions of Hg in surface sediments from the middle portion of the Central Indian Ridge were investigated. Highly elevated Hg concentrations (up to 13,000 ng/g) in sediments near the hydrothermal vent are associated with intense hydrothermal activity driven by serpentinization. The hydrothermal impact on these sediments is also evident in the REE CN fractionation pattern with a remarkably strong positive europium (Eu) anomaly. Most volcanic and hydrothermal Hg in the study area is preferentially precipitated with sulfides; in the hydrothermal vent area, however, scavenging by Fe-Mn hydroxides is another significant removal pathway of Hg. Thus, such precipitation and production of sulfides and hydroxides are a major cause of local enrichment of Hg around the mid-ocean ridge. Most sediments show limited or no mass-independent fractionation (Δ199Hg = +0.02 ± 0.21‰, 2σ, n = 15), indicating that syngenetic magmatic or mantle-derived materials are the dominant Hg source. However, the large variation in mass-dependent fractionation was observed, especially in the vent-distal sediments (δ202Hg = −1.10 ± 0.80‰, 2σ, n = 11), which occurred mainly during the formation of the sulfides and may be associated with preferential precipitation of lighter isotopes. Our study demonstrates that an off-axis high-temperature hydrothermal system driven by exothermic serpentinization of ultramafic mantle rocks may serve as a significant Hg source and provides further insights into grasping the behavior of hydrothermal and volcanogenic Hg in active deep-sea ridge systems. • Extremely high Hg concentrations are observed in the serpentinization-driven hydrothermal vent sediments. • Sequential extraction demonstrates the depositional pathways of Hg in deeps-sea ridge system. • Most volcanic and hydrothermal Hg is sequestered by co-precipitation with sulfides. • Fe-Mn oxides are another prevalent Hg speciation, especially in the hydrothermal sediments. • Significant Hg-MDF may occur during the formation of Hg-sulfide precipitates. [ABSTRACT FROM AUTHOR]

Clay mineralogical analysis and scanning electron microscope (SEM) analysis were performed on deep-sea sediments cored on the Benham Rise (core MD06-3050) in order to reconstruct long-term evolution of East Asian Summer Monsoon (EASM) rainfall in the period since 2.36 Ma. Clay mineralogical variations are due to changes in the ratios of smectite, which derive from weathering of volcanic rocks in Luzon Island during intervals of intensive monsoon rainfall, and illite- and chlorite-rich dusts, which are transported from East Asia by winds associated with the East Asian Winter Monsoon (EAWM). Since Luzon is the main source of smectite to the Benham Rise, long-term consistent variations in the smectite/(illite + chlorite) ratio in core MD06-3050 as well as ODP site 1146 in the Northern South China Sea suggest that minor contributions of eolian dust played a role in the variability of this mineralogical ratio and indicate strengthening EASM precipitation in SE Asia during time intervals from 2360 to 1900 kyr, 1200 to 600 kyr, and after 200 kyr. The EASM rainfall record displays a 30 kyr periodicity suggesting the influence of El Niño–Southern Oscillation (ENSO). These intervals of rainfall intensification on Luzon Island are coeval with a reduction in precipitation over central China and an increase in zonal SST gradient in the equatorial Pacific Ocean, implying a reinforcement of La Niña-like conditions. In contrast, periods of reduced rainfall on Luzon Island are associated with higher precipitation in central China and a weakening zonal SST gradient in the equatorial Pacific Ocean, thereby suggesting the development of dominant El Niño-like conditions. Our study, therefore, highlights for the first time a long-term temporal and spatial co-evolution of monsoonal precipitation in East Asia and of the tropical Pacific ENSO system over the past 2.36 Ma. [ABSTRACT FROM AUTHOR]

This study analyzed grain size and elemental concentrations (Al, Mg, Fe, and rare earth elements (REEs)) in 91 surface sediments to elucidate sediment provenance in the Yellow Sea. Elemental concentrations were normalized by Al concentration ( C element / C Al ) to minimize the sediment grain-size effect (GSE). However, noticeable linear relationships between Al concentration (or mean grain size) and the ratio (e.g., Mg/Al or Fe/Al) appeared unexpectedly in pair diagrams. The spatial distribution patterns of Fe/Al and Mg/Al ratios were also similar to the pattern of mean grain size. This implies that the GSE was not removed completely, even after the normalization process. Thus, great care must be taken when applying the ratios of C element / C Al as a proxy of sediment provenance. To improve provenance discrimination of the sediments in the Yellow Sea, the difference between the REE distribution patterns of Chinese and Korean river sediments, expressed as δ ( δ = REE ∗ (La) − REE ∗ (Lu)), was calculated, and the spatial distribution patterns of the δ values were mapped. The δ values gradually increased from the western to the eastern part of the Yellow Sea, except for low δ values in the southeastern part of the Yellow Sea. This result indicates that the majority of Chinese and Korean river sediments are accumulating near to their respective coasts, except for a deposit along the southwestern coast of Korea in which a considerable amount of sediment from Chinese rivers has been accumulating. [ABSTRACT FROM AUTHOR]