地球科学最新文献

{"title":"Coseismic Rupture and Early Afterslip of the 2023 Herat (Afghanistan) Earthquake Sequence: Insights From Sentinel-1 Radar Observations","authors":"Zhenjiang Liu,&nbsp;Zhenhong Li,&nbsp;Chen Yu,&nbsp;Chuang Song,&nbsp;Jiatong Wang,&nbsp;Xuesong Zhang,&nbsp;Xiaoning Hu,&nbsp;Jianbing Peng","doi":"10.1029/2024JB029495","DOIUrl":"https://doi.org/10.1029/2024JB029495","url":null,"abstract":"<p>Between 7 and 15 October 2023, a series of devastating earthquakes struck Herat in northwestern Afghanistan, a region in which few historical earthquakes have been recorded, causing severe human casualties. In this study, we investigate the co- and post-seismic deformation mechanisms of the 2023 Herat earthquake sequence using Sentinel-1 radar interferometry. The 4-month postseismic deformation time series exhibits a significant, gradually accumulating, localized deformation in the south of the coseismic displacements. Coseismic slip is first modeled using a simplified planar fault geometry with multiple segments, then enhanced using a curved geometry based on the fault trace inferred from Sentinel-2 images analysis. Postseismic afterslip is the dominant mechanism of postseismic deformation, and mainly occurs in the down-dip of the coseismic rupture zone and an activated secondary fault, with a maximum afterslip of ∼0.3 m at 120 days. Co- and post-seismic slip behaviors seem to indicate that coseismic rupture mainly occurs on the north fault plane with spatially varying frictional properties, and then activated an aseismic secondary fault in the south. Additionally, we infer that structural complexity in fault systems (such as the complex fault network in the basin north of Herat) may act as barriers to rupture propagation, and static stress changes from extremely early afterslip may further promote rupture of subsequent events, both of which together cause the cascading rupture of the Herat seismic sequence.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Ionospheric Response During the Super Geomagnetic Storm on May 10–11, 2024","authors":"Qingtao Wan,&nbsp;Guanyi Ma,&nbsp;Guiping Zhou,&nbsp;Jinghua Li,&nbsp;Jiangtao Fan","doi":"10.1029/2024JA033627","DOIUrl":"https://doi.org/10.1029/2024JA033627","url":null,"abstract":"&lt;p&gt;The ionospheric response in the Americas and Asia region was studied during the super geomagnetic storm on 10–11 May, 2024, characterized by a minimum Dst of −412 nT. Global Navigation Satellite System receivers at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;100&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;mi&gt;W&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $100{}^{circ}mathrm{W}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;100&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $100{}^{circ}mathrm{E}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; were utilized to study total electron content. Additionally, electron density profiles from Constellation Observing System for Meteorology Ionosphere and Climate occultation, foF2 from ionosondes, vertical ion drift from JULIA Medium Power radar, latitudinal distribution of electron density from Swarm B, and the [O/N2] ratios from TIMED/GUVI were also analyzed. The ionosphere in the Americas exhibited a positive storm, while Asia showed a negative storm. The presence of prompt penetration electric field and the equatorward wind surge were indicated by the increased upward ion drift and the enhancement of equatorial ionospheric anomalies (EIA). The observations of [O/N2] confirm the existence of equatorward expansion of neutral atmosphere, and the time delay of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${Delta }TEC$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; peak at mid-latitudes was related to the equatorward wind surge. For the first time, we investigated the dominant physical mechanism of ionospheric disturbance at different latitudes by analyzing the variation of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${Delta }TEC$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; peak time with latitude. The estimated speed of disturbance winds was approximately 660 m/s at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;50&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $50{}^{circ}mathrm{N}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and 150 m/s at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;37&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $37{}^{circ}mathrm{N}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. The","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrological changes in the East Asian monsoon region around 4.2 ka precisely reconstructed from multi-proxy stalagmites","authors":"Chao-Jun Chen ,&nbsp;Yao Wu ,&nbsp;Jun-Yun Li ,&nbsp;Hai-Wei Zhang ,&nbsp;Hai Cheng ,&nbsp;Chuan-Chou Shen ,&nbsp;You-Feng Ning ,&nbsp;Dao-Xian Yuan ,&nbsp;R. Lawrence Edwards ,&nbsp;Jian Zhang ,&nbsp;Ting-Yong Li","doi":"10.1016/j.quascirev.2025.109321","DOIUrl":"10.1016/j.quascirev.2025.109321","url":null,"abstract":"<div><div>The 4.2 ka event was considered a climatic event that influenced ancient cultural transitions during the Middle-Late Holocene. However, whether this was a global climate event, remains controversial. Although some studies have discussed the changes in the Asian summer monsoon during the 4.2 ka event, the climate change patterns in the Yangtze River Basin (YRB) during this period remain unclear. In this study, we utilized multi-proxy (δ¹⁸O, δ¹³C, and Mg/Ca) records from stalagmite YK1306 to reconstruct the climatic changes in the YRB during 3000∼5000 yr BP. Based on comparative analysis of the high-resolution stalagmite records and other geological proxies within this region, the increased precipitation in the YRB during 4300∼4000 yr BP led to frequent flooding disasters, while double droughts occurred during 4000∼3700 yr BP and 4500∼4300 yr BP. Although there are differences in the characteristics of the 4.2 ka event recorded by speleothems across the Asian summer monsoon region, the 4.2 ka event indicated in the δ¹⁸O and δ¹³C records from speleothems in the YRB is inconsistent with the previously defined 4.2 ka event. The transition of El Niño-Southern Oscillation (ENSO) events resulted in the occurrence of flooding and droughts in the YRB during 4500∼3700 yr BP. This study not only provides new evidence of the hydrological changes in the YRB, but also helps evaluate the impact of climate change on civilizations in the YRB in the Late Neolithic.</div></div>","PeriodicalId":20926,"journal":{"name":"Quaternary Science Reviews","volume":"357 ","pages":"Article 109321"},"PeriodicalIF":3.2,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Storms, Sea Ice, and Microseismic Noise in Alaska","authors":"Sebin John,&nbsp;Michael E. West","doi":"10.1029/2024JB030603","DOIUrl":"https://doi.org/10.1029/2024JB030603","url":null,"abstract":"<p>Using 155 distributed seismic stations spanning Alaska and western Canada, we document how environmental factors like storms and sea ice influence microseismic noise. We examine power spectral densities of continuous seismic data and focus on secondary microseisms (5–10 s) and short period secondary microseisms (1–2 s) from 2018 to 2021. We cross-correlate the height of ocean waves across the region with the power spectral density time series. We find that the Gulf of Alaska is the dominant source of secondary microseisms in Alaska. The eastern Gulf, in particular, produces more energetic secondary microseisms despite, at times, lower overall wave amplitudes. We find that the short period secondary microseismic noise is produced in the coastal waters and attenuates quickly moving inland. We show that this band is heavily modulated by the influence of sea ice in the coastal ocean by comparing it with sea ice concentrations. We also document how these two microseismic bands vary seasonally and spatially as they respond to different environmental phenomena. We find that this seismic energy closely tracks the seasonal arrival and departure of sea ice in the coastal waters. We also compare the inter-annual variability of short period secondary microseisms in the northern Arctic from 2009 to 2023 with shorefast ice data. The findings of this study are crucial for monitoring global climate change through seismology.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030603","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143762125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estimating Total Dissolved Solids in Groundwater Using Machine Learning Models","authors":"Sumita Gulati, Anshul Bansal, Ashok Pal","doi":"10.1007/s11053-025-10480-3","DOIUrl":"https://doi.org/10.1007/s11053-025-10480-3","url":null,"abstract":"<p>Accurate forecasting of water quality is pivotal for compelling pollution control and enhanced water management practices. This study predicted total dissolved solids in groundwater samples from West Bengal, India, using data sourced from the Central Pollution Control Board for the span 2020–2022. The parameters include temperature, pH, conductivity, biological oxygen demand, nitrate-N + nitrite-N, fecal coliform, total coliform, fluoride, and arsenic. Employing a diverse set of machine learning models including seven regression models, three support vector machines (SVMs), three artificial neural networks (ANNs), and an adaptive neuro-fuzzy inference system (ANFIS), the study evaluated model performance using root mean square error (RMSE), coefficient of determination (R²), mean square error (MSE), and mean absolute error (MAE). The assessment revealed that the ANN trained with Bayesian regularization emerged as the most effective, boasting the lowest errors (RMSE = 0.00147, MSE = 0.0005, MAE = 0.0112) and the highest R² (0.97), ensuring superior precision. Additionally, ANN trained with Levenberg–Marquardt and ANFIS exhibit commendable performance, showcasing minimal errors and high R² values. Among the non-ANN models, boosted tree displayed a lower RMSE (0.08246) and a higher R² (0.62), while a linear SVM demonstrated balanced performance with RMSE of 0.0877 and R² of 0.57.</p>","PeriodicalId":54284,"journal":{"name":"Natural Resources Research","volume":"38 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143758246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding Long-Term Streamflow Response to Snowfall Change: Insights From a Multivariate Analysis","authors":"Ying Hou, Juntai Han, Ross Woods, Yuhan Guo, Yuting Yang","doi":"10.1029/2024wr038215","DOIUrl":"https://doi.org/10.1029/2024wr038215","url":null,"abstract":"Ongoing climate change is modifying snow dynamics, further altering streamflow (<i>Q</i>) in cold regions. Despite extensive research over the past decades, the impact of changes in snow on mean annual <i>Q</i> remains debated, and the underlying mechanisms driving these responses are still unclear. In this study, we employ the Budyko framework to establish multivariate relationships between a Budyko model parameter and several variables, including snowfall fraction (<i>f</i>_s), across 931 carefully selected snow-influenced catchments in the Northern Hemisphere. Our results show that the average elasticity of <i>Q</i> to <i>f</i>_s across all catchments is 0.13. However, mean annual <i>Q</i> responses vary among catchments, with 78% of catchments experiencing decreased <i>Q</i> and others exhibiting increased <i>Q</i> with declining <i>f</i>_s. These variations are manifested in decreased warm-season <i>Q</i> and increased cold-season <i>Q</i>, respectively. Additionally, attribution analysis of <i>Q</i> change highlights a critical role of <i>f</i>_s changes as a second-order control on <i>Q</i> after precipitation. Examining possible mechanisms behind the varying <i>Q</i> responses reveal that the influence of <i>f</i>_s on snowmelt intensity and snow season available energy is more pronounced in catchments exhibiting positive <i>Q</i> feedback to <i>f</i>_s. In contrast, its impact on rainfall intensity and the asynchrony between available energy and liquid water input is greater in catchments displaying negative <i>Q</i> feedback to <i>f</i>_s. Our findings enhance the understanding of <i>Q</i> responses to changing <i>f</i>_s and provide valuable insights for water resource management in snow-influenced regions in a warming climate.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"44 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143758609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The thermal expansion of the clinopyroxene and garnet polymorphs of Na2MgSi5O12 determined by X-ray powder diffraction","authors":"E. K. Tripoliti,&nbsp;A. R. Thomson,&nbsp;D. P. Dobson,&nbsp;P. F. Schofield,&nbsp;I. G. Wood","doi":"10.1007/s00269-025-01315-x","DOIUrl":"10.1007/s00269-025-01315-x","url":null,"abstract":"<div><p>The temperature dependence of the unit-cell parameters of synthetic Na(Mg_0.5Si_0.5)Si₂O₆ clinopyroxene and Na₂MgSi₅O₁₂ garnet were measured, at atmospheric pressure, using X-ray powder diffraction, from 40 K up to their decomposition temperatures (673 K and 793 K respectively). At 300 K the cell parameters were found to be: (i) <i>a</i> = 9.4073(3) Å, <i>b</i> = 8.6487(3) Å, <i>c</i> = 5.2685(2) Å, <i>β</i> = 108.113(2)°, <i>V</i> = 407.41(3) ų and <i>ρ</i> = 3.286 g/cm³, for Na(Mg_0.5Si_0.5)Si₂O₆ pyroxene in space-group <i>P2/n</i> with Z = 4 and (ii) <i>a</i> = 11.4155(7) Å, <i>V</i> = 1487.61(5) ų and <i>ρ</i> = 3.561 g/cm³ for Na₂MgSi₅O₁₂ garnet in space-group <i>Ia</i><span>(overline{3})</span><i>d</i> with Z = 8. The thermal expansion tensors have been calculated and analysis of the lattice parameters in terms of a Grüneisen-Debye model is used to estimate the Debye temperature and the incompressibility of the two materials at ambient pressure.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"52 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00269-025-01315-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On Anguillosyllis cf. hessleri Maciolek, 2020 – A species complex from the Clarion-Clipperton zone, abyssal central Pacific","authors":"Regan Drennan ,&nbsp;Lenka Neal ,&nbsp;Helena Wiklund ,&nbsp;Eva C.D. Stewart ,&nbsp;Muriel Rabone ,&nbsp;Corie Boolukos ,&nbsp;Innes Clatworthy ,&nbsp;Zuzana Jungmanova ,&nbsp;Thomas G. Dahlgren ,&nbsp;Adrian G. Glover","doi":"10.1016/j.dsr.2025.104453","DOIUrl":"10.1016/j.dsr.2025.104453","url":null,"abstract":"<div><div>The benthic annelid fauna of polymetallic nodule fields in the eastern Clarion-Clipperton Zone (CCZ) has recently been the subject of taxonomic investigations aiming to document the biodiversity of this region. While investigating the annelids, a particularly high diversity was discovered within the genus <em>Anguillosyllis</em> Day, 1963 using a combination of morphological and molecular approaches. Initially, 38 specimens of <em>Anguillosyllis</em> were assigned to the known CCZ species <em>Anguillosyllis hessleri</em> Maciolek, 2020 based on morphological examination, including examination of the type specimen. However, our genetic data revealed that these specimens represent four distinct lineages (putative species) based on COI and 16S markers. Further morphological investigation using SEM revealed a complex structure of the prostomium, which could potentially differentiate these lineages. However, as no molecular or SEM data are available from the type specimen of <em>A. hessleri</em>, we cannot ascertain which, if any, of these lineages represent the known species described by Maciolek (2020). Thus, currently, we can only assign CCZ specimens to <em>Anguillosyllis</em> cf. <em>hessleri</em> and further distinguish the lineages by assigning each a unique code in the form of “NHM_####”. The SEM observations are the first reported for <em>Anguillosyllis</em>, revealing new taxonomic characters that may be used to disentangle the <em>A. hessleri</em> species complex and be of use in taxonomy of <em>Anguillosyllis</em> in general.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"220 ","pages":"Article 104453"},"PeriodicalIF":2.3,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating the Lithospheric Structure and Regional/Residual Bouguer Anomalies in Peninsular India Through Potential Field Modeling and Thermal Analysis","authors":"Prakash Kumar,&nbsp;William Kumar Mohanty","doi":"10.1029/2024JB029341","DOIUrl":"https://doi.org/10.1029/2024JB029341","url":null,"abstract":"<p>The Indian lithospheric mantle has been deeply influenced by geological processes such as rifting, plume activity, and collision-subduction events. Therefore, it is vital to understand the genesis of the Indian continental lithosphere and its eventual destruction by intraplate tectonic processes. The present study provides an integrated perspective of the crust and lithospheric mantle of the Indian peninsula and surrounding regions, derived from the combined modeling of topography data and geoid anomalies, constrained by seismic observations. The method involves local isostasy with a temperature-dependent density in the lithospheric mantle. The seismic Moho depth data of 361 data points from receiver functions (RFs) and deep seismic sounding (DSS) have been utilized in the modeling procedure. Crustal thickness across the region varies between 34 and 70 km, while the lithosphere-asthenosphere boundary (LAB) depth ranges from 140 to 250 km, with the maximum depths located beneath the Indo-Gangetic Plain. In contrast, the southern Indian shield exhibits an average LAB depth of approximately 170 km. Additionally, a gradual increase in LAB depth from western to eastern Dharwar has been observed, which may correspond to the combined influences of plume activity and thermo-chemical erosion associated with extensive metasomatism over time. Furthermore, lateral variations in crustal density are examined through residual gravity anomalies, revealing notable gravity lows in sediment-rich regions such as the Ganga and Godavari basins, along with pronounced positive anomalies in areas characterized by dense rock formations.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Central South Pacific bottom water response to thermohaline circulation crisis during the Middle Pleistocene Transition","authors":"N. Mahanta,&nbsp;Sunil K. Das,&nbsp;Raj K. Singh","doi":"10.1016/j.quascirev.2025.109344","DOIUrl":"10.1016/j.quascirev.2025.109344","url":null,"abstract":"<div><div>Mid-Pleistocene Transition (MPT) is still enigmatic in paleoclimatology, and the major disruption of the ocean thermohaline circulation (THC) system, which is known as the THC crisis during the MPT from ∼950 to 860 thousand years ago, is even more puzzling. Hence, benthic foraminifera and Iceberg rafted debris (IRD) of the Central South Pacific (CSP), International Ocean Discovery Program Site U1540 are examined, and compared with existing Nd isotope records (ε_Nd) from the South and North Atlantic, and δ¹³C of South Atlantic and Equatorial Pacific to evaluate the properties and influence of CSP bottom water during THC crisis in comparison to pre and post-THC crisis. Our data suggests variability in CSP bottom water conditions from oxic to suboxic throughout the MPT. During the pre-THC crisis (MIS 38-26), bottom water was suboxic with low bottom water current strength, which continued up to the Marine Isotopic Stage (MIS) 25, except for MIS 31. Evidence of a strong bottom water current with a high oxic species population and low IRD is found at MIS 31. During the THC crisis, between MIS 25 and 23, a sharp decline in the coarse sediment fraction (&gt;63 μm), oxic species and <em>Globocassidulina subglobosa</em> population is observed, which suggests sluggish bottom water at the CSP. However, during MIS 22, bottom water was relatively strong, marked by an increase in <em>G. subglobosa</em> and <em>Nuttallides umbonifera</em> and oxic species abundances. This suggests stronger southern source bottom water, which may reach up to the North Atlantic due to reduced northern sourced bottom water mass and is consistent with the interpretation of observed ɛ_Nd value. After the THC crisis, bottom water became better oxygenated, especially during the interglacials with high bottom water current strength, which continued post-MPT period. Bottom water current strength nearly follows the ACC strength during the MPT except for MIS 22.</div></div>","PeriodicalId":20926,"journal":{"name":"Quaternary Science Reviews","volume":"357 ","pages":"Article 109344"},"PeriodicalIF":3.2,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}