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Abstract Detrital minerals in sediments can provide insight into sedimentary provenance and depositional environments. Here we report a record of heavy minerals of a 300.1 m long core recovered from the western south Yellow Sea, which was dated back to the late Pliocene (~3.5 Ma). Results of detrital mineral analysis show that sediments are dominated mainly by silicate minerals sourced from the Chinese mainland through river inputs. Heavy minerals suggest that marine transgression occurred around 76–84 m depth of the core depth, about at 792–840 ka BP. The upper part of the core (0–76 m) is dominantly marine and the lower part (below 84 m) is terrestrial. From the Miocene to Early Pleistocene, the Yellow Sea area generally subsided; the deposition center began to move from west to east, therefore the content of fine sand increased relatively in the core sediment. Meanwhile, under the influence of depression evolution in the Subei Basin, the paths of rivers were shifted, as a result the contents of augite and garnet changed, sediments in the study area were dominated by proximal sediments sourced from the Subei Basin, possibly of mixed sediments of the Yellow River and Yangtze River. The lower part of the core was characterized by a dramatic increase in augite with hornblende and epidote as dominant minerals. In the Early Pleistocene, under the background of subsidence in the Yellow Sea area, while transgression occurred, rivers shifted southward. Comparison with the mineral composition of adjacent core NHH01 and surface sediments from the region suggests the Yellow River dominated the study area, and the old Yangtze River input being occasionally dominant. The heavy mineral assemblage was dominated by hornblende and epidote, as well as mica, garnet and authigenic pyrite in some sediment layers. [ABSTRACT FROM AUTHOR]

Data on grain size and heavy mineral composition for surface sediments on the Prydz Bay continental shelf was analysed to identify sediment features and provenance. The grain size composition of surface sediments indicate spatial variations in the glaciomarine environment and the key factors influencing sedimentation, which on the shelf include topography/water depth, currents and icebergs. The study area was divided into two sections by Q-type factor analysis: section I included Prydz Channel, Amery Basin and Svenner Channel, and section II included Four Ladies Bank, Fram Bank and the area in front of the Amery Ice Shelf. Sedimentation in section I is mainly controlled by currents and topography/water depth. However, in section II, icebergs/floating ice masses, the Amery Ice Shelf and currents have prominent effects on sedimentation. The heavy mineral composition indicates that surface sediments on the eastern side of the bay, including Four Ladies Bank, are primarily derived from Princess Elizabeth Land. Sediments in the area in front of the Amery Ice Shelf, Svenner Channel, Amery Basin and Prydz Channel have a mixed source from the eastern regions around the bay, including the Prince Charles Mountains and Princess Elizabeth Land. The contribution from Mac. Robertson Land to sediment at Fram Bank is limited. [ABSTRACT FROM PUBLISHER]

To understand the modern sedimentation and land-sea interaction processes in the Asian margin seas, we analyze rare earth element contents (REE, i.e., La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and grain sizes, detrital minerals from 158 surface sediment samples collected from the western Gulf of Thailand (GoT). The results reveal that the REE contents ranged from 25.42 μg/g to 201.21 μg/g, with an average value of 137.21 μg/g, and that the GoT is characterized by higher accumulations of LREE relative to HREE, together with negative Eu anomalies. Based on the spatial distribution characteristics of REE contents, δCe and δEu, the western GoT can be classified into three geochemical provinces. The Province I covers the northern and northwestern coastal zones of the GoT, including the entire upper GoT; its coarse size fraction and distribution pattern of hornblende- and quartz-dominated minerals caused REE contents to be the lowest, and these sediments were mainly derived from the rivers around the upper GoT, including the Chao Praya River and the Kea Klong River. The Province II is located in the central GoT and has the highest REE concentrations due to finer sediment composition and higher contents of zircon, authigenic pyrite, and biogenetic limestone. The Province II has two accumulation centers around Samui Island and Koh Chang Island, with REE spatial distribution influenced by the seasonal setting and mixed derived from multiple provenances around the GoT. The Province Ш is located in the lower GoT, close to Malaysia. The sediment type in this region is similar to that of Province I except for different detrital mineral compositions, especially the presence of siderite that is responsible for higher REE contents. The sediments in this region exhibits similar distribution patterns to those of terrestrial materials from the Malaysian peninsula such as that from the Kelantan River. The transportation processes of sediments in this region are mainly controlled by the coastal current. [ABSTRACT FROM AUTHOR]

Sediment core OS03-1 retrieved from the Akademia Nauk Rise in Southern Okhotsk Sea was analyzed for the contents of rare earth elements (REEs) and combined with carbon isotope (δ 13 C) time series of benthic foraminifera to infer changes in terrigenous accumulation and bottom water ventilation on glacial–interglacial timescales in the study area. The age model of OS03-1 was constructed by a combination of foraminifer δ 18 O stratigraphy and 14 C AMS dating, revealing that the 380 cm long core provides a window on climate change in the southern Okhotsk Sea since ∼180 ka. A grain size-controlled-REE content shows strong glacial–interglacial changes. The Cerium and Europium anomalies vary from 0.89 to 1.32 and from 1.14 to 1.37, respectively. The (La/Yb) N values range between 0.55 to 0.92. Both results suggest a significant contribution of volcanic debris in the core sediments. In addition, the relationships between Sm vs. Nd suggest main contribution origin from the Amur River and sea ice during warm intervals and from the sea ice during cold intervals, indicating that the sea ice played an important role in transporting terrigenous materials to the study site in the southern Okhotsk Sea. During the last 180 ka, the mass accumulation rates (MAR) of ∑REEs are relatively higher during glacials and lower during interglacials with a peak accumulation during the early deglacial period. We infer that an intensified Mongolia High is responsible for the first-order accumulation pattern of ∑REEs in the southern Okhotsk Sea by mediating the dynamic changes in sea ice extent. Furthermore, six δ 13 C minima are associated with intensified Asian monsoon (AM) precipitation and maximum MARs of ∑REEs, indicating that the dominance of barrier layer effects by high fresh water input through sea ice melting. The maximum MAR of ∑REEs during the Marine Isotope Stage (MIS) 5c coincides with the minimum of benthic foraminiferal δ 13 C, indicating a major interruption of ventilation in the bottom water in the Okhotsk Sea. The major low ventilation event in the deep water of the Okhotsk Sea appears to be dampened by a cooling condition and a major blooming of surface productivity preceded the event. [ABSTRACT FROM AUTHOR]

Abstract: Sediments from the continental shelf/coastal region bear significant signals of sea-level, climate change as well as local tectonic information. This study presents a high-resolution magnetostratigraphic and rock magnetic study of a 212.4m core (BH08, with a basal age of 1.06Ma) recovered from the shallow (<30m below sea level) Bohai Sea, China. Astronomical tuning based on the sediment redness (a*) of core BH08 allows the construction of a high-resolution chronology that is assisted by magnetostratigraphic data. Sedimentology and associated proxies (grain size and redness) indicate that the cyclic alternation of neritic/littoral sandy deposits and terrestrial silts/clayey silts was mainly controlled by changes in sea-level and associated base-level at glacial–interglacial timescales. The a* record of the core can be correlated with marine δ18O records at 40- and 100-kyr cycles, indicating that the sediments in the study area are continuous at least at orbital timescales regardless of significant base-level variations. This is likely due to continued subsidence in the basin and creation of accommodation space. The significant lower sedimentary accumulation rates since 750ka might be due to the deviation of the depositional locus from core site because of extreme low sea-level stands during the glacials since the Mid-Pleistocene transition (MPT). Especially the glacial sea-level lowstands might have resulted in bypassing or erosion of sediments on the BH08 core site during peak glacials (MIS 6, MIS 10 and MIS 16), limiting the sediment preservation potential. This study documents the longest Quaternary sedimentary succession in the Bohai Sea and provides, for the first time, a clear link between sedimentation in the area and glacial–interglacial climate-driven sea-level changes. This study also highlights the feasibility of astronomical tuning to obtain high-resolution chronology for shallow shelf deposits, which is otherwise very difficult to be achieved on the basis of magnetostratigraphic data alone. [Copyright &y& Elsevier]

To understand the modern sedimentation and land-sea interaction processes in the Sunda Shelf, we evaluated the rare earth element (REE) compositions, the total organic carbon (TOC) contents, grain sizes, and detrital minerals of 39 surface sediments, collected from the western Sunda Shelf. All of the sampled sediments are characterised by a higher content of light REEs (LREEs) relative to the content of heavy REEs (HREEs) with negative Eu anomalies. The total content of REE (ΣREE) in the sediments ranges from 7 μg/g to 193 μg/g, with an average of 119 μg/g. Due to the uneven spatial distribution of REEs in the study area, a Q-cluster analysis is applied to the mean grain size (Mz), ∑REE, δEu, δCe, (La/Yb) N , and (Gd/Yb) N data. On this basis, the study area can be classified into three geochemical provinces. The north to central zone in the study area is designated as province I, which has the highest REE content among the three provinces. This is a result of the finer grain size, dominance of siderite, and higher TOC contents of the sediments in province I. The REE content of province II in the southwest coastal zone is lower than that of province I due primarily to a coarser grain size and high quartz, biodetritus, and plagioclase contents. Covering the central coastal zone, province III has the lowest REE content among the three provinces because of the extremely coarse grain size and very high quartz and biodetritus contents. The upper continental crust (UCC)-normalised REE patterns differ markedly among the three provinces, thereby indicating different provenances and transport mechanisms. Based on the provenance discrimination plot and the UCC-normalised REE patterns of these three provinces and adjacent rivers, we infer that province I is largely fed by the Mekong and Kelantan rivers. The fine-grained sediments from these rivers are transported to north and central zone by the northeast monsoon current. The Pahang River is identified as the main sediment source of province II. The coarse-grained sediments from this river mostly accumulate near the estuary via hydrodynamic sorting, while finer-grained sediments are transported to the south by the southward coastal currents. The sediments in province III are inferred as being primarily the result of coastal erosion due to the strong wave energy in this area, as well as offshore and longshore sediment transport acting, in parallel to the coast line. Our study can serve as a reference for studying the diffusion and transport processes of mountainous river sediment and the evolution of the paleoclimate and paleoenvironment in tropical low-latitude regions. • Surface sediments of the western Sunda Shelf can be classified into three geochemical provinces. • Grain size and heavy minerals play important constraint roles on REE distribution. • Different geochemical provinces have their unique provenances. • Erosion, transport and deposition are mainly controlled by northeast monsoon current, coastal current and wave energy. [ABSTRACT FROM AUTHOR]