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The upper water‐column dynamics and surface productivity variability in the Northeastern Atlantic Ocean across the Marine Isotope Stage (MIS) 7 interglacial complex is not well understood. Here, we present high‐resolution planktic foraminiferal proxies combined with Artificial Neural Network based‐sea‐surface temperature (SST) and ice‐rafted detritus records from International Ocean Discovery Program Site U1385, SW Iberian Margin for the intervals representing MIS 8 deglaciation, MIS 7 interglacial complex and MIS 6 glacial inception. The long‐term SST pattern is modulated by insolation and precession parameters across the MIS 7 interglacial complex and is superimposed by the millennial‐scale variability (stadials at ∼250, ∼243, ∼230, ∼221, ∼203, ∼196 and ∼192 ka). The regional SST records indicate high temperature gradient (∼6°C) between the sub‐polar North Atlantic Ocean and the SW Iberian Margin during MIS 7d which enhanced the moisture transport from mid‐to‐high latitudes. Further, low obliquity with low insolation induced cooling at high latitudes and promoted the expansion of ice‐sheets during MIS 7d. Comparison of our faunal proxies with the published marine and terrestrial records from SW Europe and western Mediterranean Sea suggested a weakening and southward shift of Azores High (AH) pressure system, similar to the present‐day (−) NAO‐like atmospheric configuration during the early phases of MIS 7e, MIS 7c and MIS 7a, resulting reduced surface productivity of SW Iberian Margin. During the late phases of MIS 7e, MIS 7c and MIS 7a, the AH pressure system strengthened and shifted northward causing the intensification of the trade winds, a scenario similar to present‐day (+) NAO‐like atmospheric configuration, which resulted in high surface productivity of SW Iberian Margin. Key Points: Long‐term sea‐surface temperature (SST) trend across the Marine Isotope Stage (MIS) 7 interglacial complex is modulated by insolation and precessionHigh SST gradient between sub‐polar North Atlantic and SW Iberian Margin and low obliquity enhanced the expansion of ice‐sheets during MIS 7dSurface productivity during MIS 7e, MIS 7c, & MIS 7a is driven by a NAO‐like atmospheric configuration [ABSTRACT FROM AUTHOR]

Palaeo-monsoon and palaeoclimate conditions over Southeast Asia are a matter of debate despite notable studies on the continental and oceanic sedimentary record. The present study investigates the environmental magnetic and geochemical records preserved in the deep marine sediments of the northeastern (NE) Arabian Sea to elucidate the erosion history of the western Himalayas and its link with the prevailing hydroclimatic conditions since the late Miocene. For this, the sediment core retrieved during International Ocean Discovery Program (IODP) Expedition 355 at Site U1457 in the NE Arabian Sea has been explored. The results reveal that the hydroclimatic conditions were predominantly arid during the late Miocene, except for humid intervals from 6.1 Ma to 5.6 Ma. Humid climate conditions in the Indus River Basin returned during the mid-Pliocene and continued to the Pleistocene with an intense chemical weathering regime from 1.9 Ma to 1.2 Ma. The dominant sediment source to the NE Arabian Sea at Site U1457 during the late Miocene and the Pliocene was the Indus River, while during the Pleistocene, mixed sediments brought by the Indus River and the Peninsular Indian rivers were observed. The sediment contribution from a chemically less altered mafic source (the Deccan basalts) increased between 1.2 Ma and 0.2 Ma, possibly linked to a weak Indian Summer Monsoon. The summer monsoon wind strength and associated shift in the Inter-Tropical Convergence Zone (ITCZ) influenced the dominant sediment provenance at Site U1457 of the Laxmi Basin. [ABSTRACT FROM AUTHOR]

The present study deals with the biostratigraphic framework of Late Cretaceous sediments of the subsurface Well (DNG) "A" (2085–1840 m depth) from the Raghavapuram/Chintalapalli Shale of the Krishna‐Godavari Basin and analyzed the palynological assemblage. The recorded palynological assemblage is dominated by marker dinoflagellate cyst viz. Areoligera coronata, Areoligera senonensis, Heterosphaeridium spinaconjunctum, Nelsoniella aceras, Nelsoniella semireticulata, Odontochitina porifera, Xenascus ceratioides, and Xenascus gochtii species. The last occurrence (LO) of significant species of dinoflagellate cysts is considered for the biostratigraphic establishment. On the basis of dinoflagellate cyst biostratigraphy, the examined sequences correspond to the Santonian‐Campanian age. The dominance of gonyaulacoid dinoflagellate cysts is interpreted in terms of sea‐level fluctuation and other paleoenvironmental signals through this biostratigraphic establishment. The recorded dinoflagellate cysts indicate the outer neritic, cool depositional environment. The sea‐level rise, recorded in our study is linked with the transgressive phase during the Late Cretaceous (Santonian‐Campanian) period. [ABSTRACT FROM AUTHOR]

Upper water column dynamics in the eastern Arabian Sea were reconstructed in order to investigate changes in the activity of the South Asian / Indian monsoon during the early Pleistocene (c. 1.5–2.7 Ma). We used planktic foraminiferal assemblage records combined with isotopic (δ18O and δ13C) data, Mg/Ca-based sea surface temperatures and seawater δ18O records to estimate changes in surface water conditions at International Ocean Discovery Program (IODP) Site U1457. Our records indicate two distinct regimes of monsoon-induced changes in upper water structure during the periods c. 1.55–1.65 Ma and c. 1.85–2.7 Ma. We infer that a more stratified upper water column and oligotrophic mixed layer conditions prevailed during the period 1.85–2.7 Ma, which may be due to overall weaker South Asian / Indian winter (NE) and summer (SW) monsoon circulations. The period 1.55–1.65 Ma was characterized by enhanced eutrophication of the mixed layer, which was probably triggered by intensified winter (NE) monsoonal winds. The long-term trend in hydrographic changes during 1.55–1.65 Ma appears to be superimposed by short-term variations, probably reflecting glacial/interglacial changes. We suggest that an intensification of the South Asian / Indian winter monsoon circulation occurred between ∼1.65 Ma and 1.85 Ma, which is most likely due to the development of strong meridional and zonal atmospheric circulations (i.e. Walker Circulation and Hadley Circulation) because of strong equatorial East–West Pacific temperature gradients. [ABSTRACT FROM AUTHOR]

A combined biostratigraphic study of dinoflagellate cysts and foraminifera was carried out on Early Cretaceous subsurface well cutting sediments from well A (DNG) (2800–2746 m depth) from the Krishna-Godavari Basin, India. The last appearance datum of marker species of dinoflagellate cysts and planktonic foraminifera was considered for the construction of the biostratigraphic framework. The study shows dominance of Early Cretaceous marker dinoflagellate cysts Cassiculosphaeridia magna, Cribroperidinium perforans, Hystrichodinium voigtii, Kleithriasphaeridium eoinodes, and planktonic foraminifera Hedbergella aptiana, Hedbergella mitra, Hedbergella praelippa, Hedbergella tardita, Microhedbergella miniglobularis and Hedbergella mitra species. In addition to this, the dinoflagellate cyst data were compared with the dinoflagellate biozones of Austral and Tethyan provinces. Based on earlier micropalaeontological records from the Krishna-Godavari Basin and the present study, a latest Barremian-early Aptian age has been determined for the earliest marine transgression in the Krishna-Godavari Basin. The early marine incursion during late Barremian-earliest Aptian in the Krishna-Godavari Basin compared to Albian age in Cauvery Basin suggests the opening of east coast from north to south. [ABSTRACT FROM AUTHOR]

Changes in Earth's orbital parameters pace the Pleistocene glacial-interglacial cycles, although considerable ambiguity still remains over the interaction of the internal climatic variables, such as ice-sheet instability and ocean circulation that allow transitions into and out of an interglacial. Here, we analyse high-resolution planktic foraminiferal proxies including sea-surface temperature (SST) based on an Artificial Neural Network (ANN) across the last three terminations (TI, TII and TIII) and the subsequent interglacials (Holocene, Marine Isotope Stages (MIS) 5e and 7e) from IODP Site U1385, SW Iberian Margin. To demarcate the stadials and interstadials, we combined the faunal and SST records with existing data at Site U1385 including log (Ca/Ti) and benthic and planktic δ18O. The composite records reveal details of the last three terminations in terms of abrupt climatic events occurring during these terminations. Termination I included three well-known climatic events: Heinrich stadial (HS)1, Bølling/Allerød (B/A) complex & Younger Dryas (YD). Termination II was interrupted by only HS11. Termination III included HS8.2 and HS8.1 which show more resemblance to HS2 (a stadial prior to TI) and HS1, suggesting the YD is a unique feature of the last deglaciation. Additionally, TI and TII reveal similar durations (∼6 kyr) with rates of SST change (∼1.5 °C/kyr to ∼2.1 °C/kyr), whereas TIII represents a longer process (∼10 kyr) with a relatively slow rate of SST change (∼0.8 °C/kyr). The anatomy of stadials (HS1, HS2, HS11 & HS8.1) reveals a complex history ('W' shaped anatomy) with two or three cold phases sandwiching (a) brief warm event(s). The European ice-sheet melting possibly initiated the stadial cooling at the Iberian Margin followed by the mid-latitude summertime warming and the intermediate-depth water mass warming that probably induced the Laurentide ice-sheet melting resulting in the complex stadial pattern. Our records further reveal a major reorganization of the surface current system, oceanographic fronts and productivity conditions across these terminations. We also document broad similarities in the climatic evolution of Holocene, MIS 5e and 7e interglacials in terms of SST, surface productivity and current system. The long-term interglacial trends were superimposed by multiple brief cold events interrupting the Holocene (∼11.3, 9.9, 8.2, 7.1, 5.5, 2.5 ka), MIS 5e (C28, C27, C27', C27a, C27b, C26, C26', C25), and MIS 7e (∼238, 234, 231, 230 ka) interglacials. Integration of our records with benthic foraminiferal δ13C records from the Iberian Margin and central North Atlantic suggest fluctuations in the deep water convection process (which in turn were influenced by the conditions in subpolar gyre) possibly resulted in the brief cold events interrupting the interglacials at the Iberian Margin. • Surface ocean-climate changes off SW Iberian margin on centennial-millennial scale. • Sequence of climatic events interrupting the last three terminations is unique. • Surface ocean circulation showed a major reorganization across these terminations. • Stadials (HS1, HS2, HS11 & HS8.1) portrayed a complex history at IODP Site U1385. • MIS 7e showed lesser intra-interglacial variability than the Holocene & MIS 5e. [ABSTRACT FROM AUTHOR]