Evolving Earth最新文献

{"title":"Seismic risk assessment using integrated MCDM method in West Bengal, India","authors":"Monalisa Malakar ,&nbsp;Sukanta Malakar ,&nbsp;Mohd Sayeed Ul Hasan ,&nbsp;Abhishek K. Rai ,&nbsp;Vijay K. Kannaujiya","doi":"10.1016/j.eve.2024.100036","DOIUrl":"10.1016/j.eve.2024.100036","url":null,"abstract":"<div><div>Earthquakes are one of the natural hazards that threaten human lives and properties. Consequently, seismic risk assessment plays a significant role in disaster mitigation. This study estimates seismic risk in West Bengal, India, by integrating the two multi-criteria decision-making (MCDM) models: analytical hierarchy process (AHP) and Entropy. Integrated AHP-Entropy is used to determine vulnerability, seismic hazard, and coping capacity. The seismic risk was then assessed by integrating the thematic information of vulnerability, seismic hazard, and coping capacity. The results show that about 19% of the total area and 70% of the total population in West Bengal may be at very high seismic risk. The result is validated through a receiver operating characteristic curve, displaying satisfactory performance in seismic risk estimation. The findings of this study may help governmental agencies identify seismic-risk zones and establish seismic hazard plans in advance against any potential threat in the study region.</div></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"2 ","pages":"Article 100036"},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117224000062/pdfft?md5=58e6091ddcad46fef6e94cd478244d26&pid=1-s2.0-S2950117224000062-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142316256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical modeling of diagenetic reactions between albitization of K-feldspar and plagioclase feldspar in sandstone reservoirs under the influence of CO2 partial pressure","authors":"Marcos Antonio Klunk ,&nbsp;Tiago Jonatan Girelli ,&nbsp;Soyane Juceli Siqueira Xavier ,&nbsp;Farid Chemale Jr ,&nbsp;Renzo D'souza ,&nbsp;Mohuli Das ,&nbsp;Sudipta Dasgupta","doi":"10.1016/j.eve.2024.100042","DOIUrl":"10.1016/j.eve.2024.100042","url":null,"abstract":"<div><div>Diagenetic albitization has been observed in sedimentary basins around the world. This process significantly changes the original composition of sandstones and the chemistry of the formation waters under the influence of partial pressure of CO₂. The transformation of detrital feldspars into albite is considered a crucial diagenetic process in the Gulf Coast and North Sea reservoirs. Earlier studies suggest that plagioclase albitization typically happens before that of K-feldspar. In the Gulf Coast's Frio Sandstone, located in the Upper Oligocene at depths between 900 and 2400 m, detrital plagioclase is often dissolved and replaced by albite, while K-feldspar mostly dissolves without much substitution. Similarly, in the North Sea reservoirs, especially in the upper section of the Upper Triassic Lunde Formation at depths beyond 2900 m, plagioclase tends to undergo albitization, whereas K-feldspar remains largely unaffected or experiences minimal transformation. This research focuses on analyzing the differences in the albitization patterns of detrital and K-feldspar plagioclase through the KINDISP and Geochemist's Workbench (GWB) geochemical modeling tools, aiming to compare them. These diagenetic processes are crucial for reservoir geology, as they influence the concentration of silica in water, which, in turn, affects quartz cementation. This study aims to explore the variations in the albitization behavior of detrital and K-feldspar plagioclase using the KINDISP and Geochemist's Workbench (GWB) geochemical models and conduct a comparative analysis between them. Understanding these diagenetic reactions becomes relevant for reservoir geology analysis, as such phenomena control the aqueous silica concentration to some extent, which is consequently reflected in the quartz cementation. The dissolution of plagioclase and K-feldspar releases silica into the pore fluids. As the concentration of silica in the fluid increases, it leads to the precipitation of quartz as overgrowths on detrital quartz grains, a process known as quartz cementation. This was observed particularly in simulations involving temperature increases up to 150 °C, where the equilibrium between albite and anorthite was closely linked to the stability of quartz (Ben et al., 1993). The removal of feldspar through albitization reduces porosity and permeability but contributes silica to the system, which promotes quartz cementation. This, in turn, decreases the reservoir quality by filling pore spaces with secondary quartz, reducing the rock's ability to store and transmit fluids. Thus, the study highlights the importance of these diagenetic processes in reservoir evaluation, as the balance between feldspar dissolution and quartz cementation ultimately controls reservoir properties.</div></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"2 ","pages":"Article 100042"},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphospecies of potentially toxic cyanobacterium Microcystis - A review on colony formation and its global distribution","authors":"Renju Mohan ,&nbsp;Afnitha K.H ,&nbsp;Ajayakumar P ,&nbsp;Lathika Cicily Thomas ,&nbsp;K.B. Padmakumar","doi":"10.1016/j.eve.2024.100049","DOIUrl":"10.1016/j.eve.2024.100049","url":null,"abstract":"<div><div>The increased occurrence of toxic blooms of <em>Microcystis</em> is emerging as a global concern due to the health implications and associated water quality issues. <em>Microcystis</em> are single-celled ubiquitous cyanobacteria capable of forming colonies of different morphologies in various eutrophic water bodies, including freshwater, estuaries and marine systems. Their distribution and severity have increased during past decades, contributed by factors like warmer temperatures, climate change, eutrophication and other hydrological changes. They form colonies of varying shapes and sizes depending on the type of species and environmental factors. This cyanobacterial genus consists of more than 50 distinct morphological variants, mainly based on their physical characteristics like cell shape, size, colony arrangement etc. However, their greater morphological variations and phenotypic plasticity often complicate their morphological identification. Studies regarding their morphospecies are thus crucial for improved taxonomic classification, identifying the major bloom-forming species and their ecological impacts. This review has attempted to provide a brief knowledge about some of the common morphospecies of <em>Microcystis</em>, its colony formation and distribution worldwide.</div></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"2 ","pages":"Article 100049"},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bonebed amber deposits: A review of taphonomy and palaeontological significance","authors":"Pierre Cockx ,&nbsp;Ryan C. McKellar","doi":"10.1016/j.eve.2024.100032","DOIUrl":"10.1016/j.eve.2024.100032","url":null,"abstract":"<div><p>Bonebeds and amber deposits provide a wealth of palaeontological information allowing palaeobiologists to reconstruct ancient ecosystems in great detail. It is a common view that these two sources of data rarely intersect in the fossil record, owing to distinct taphonomic pathways. Nonetheless, the past decades have seen an increasing number of bonebed amber deposits reported and investigated, suggesting that some depositional environments might provide the appropriate conditions for preserving plant material and bones. By reviewing the current knowledge of the taphonomy of amber deposits and that of bonebeds, and through examination of a series of Cretaceous deposits in North America and Europe, we identify a taphonomic window that permits the long-term preservation of both materials. This synthesis allows us to provide some keys for bonebed amber prospecting, which will hopefully lead to additional finds in the field. We also review the main findings of the first comprehensive studies of bonebed amber deposits which focus on the amber assemblage, the chemistry of the fossil resin, and its stable isotopic composition, to demonstrate the utility of combined studies. This approach enables palaeobiologists to reconstruct past forest habitats by (<em>i</em>) exploring the faunal communities (especially, arthropod communities) of the forests, (<em>ii</em>) identifying the dominant source tree, (<em>iii</em>) identifying the ecological conditions, and (<em>iv</em>) characterizing the palaeogeography of the region. These findings show that amber represents a source of complementary data within bonebeds and can help achieving a better knowledge of past terrestrial habitats.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"2 ","pages":"Article 100032"},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117224000025/pdfft?md5=892761fadd4e77ade4916ff31538a9ef&pid=1-s2.0-S2950117224000025-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142021101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstruction of avulsion history of the Brahmaputra River: Rare example of a giant braided river course alteration through multi-channel multi-avulsion processes","authors":"MD. Raihanul Islam,&nbsp;Imran Khan,&nbsp;MD. Alifnur Salim,&nbsp;M.D. Musfequzzaman","doi":"10.1016/j.eve.2024.100034","DOIUrl":"10.1016/j.eve.2024.100034","url":null,"abstract":"<div><p>The avulsion scenario of the Brahmaputra has been a debated issue for quite a long time. This study aims to resolve this debate through reconstruction of the avulsion history of the Brahmaputra. We have addressed the processes, timeline and causes of the avulsion. Old maps and images from 1776 to 2023, evidence from contemporary literature and recent studies have been used in our study. We find that the process of creation of the Jamuna was started through capturing the flow of the Brahmaputra by the Jenni during the 1780s. Between 1780 and 1800 the Brahmaputra created two primary avulsion channels upstream and initiated the multi-avulsion process which was completed in the 1880s. The first avulsion channel conveyed the Brahmaputra flow into the Konaie directly and the second avulsion channel diverted the flow captured by the Jenni into the Konaie. Contemporarily, the flow-enriched Konaie switched its flow into the Jenni at downstream through an unnamed channel and the combined flow traveled through the bed of the Jenni before creating the confluence with the Ganges. In the whole process, the Konaie received, inflated and transported the dominant flow of the Brahmaputra and the Jenni became inferior over time. We have introduced a bend migration concept along with local sediment overload to focus on setting up a lower stability threshold of avulsion that led to the eruptive creation of the avulsion channels by a coupled switching mechanism imparted by high monsoonal discharges, avulsion of the Tista into the Brahmaputra and the high-magnitude floods.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"2 ","pages":"Article 100034"},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117224000049/pdfft?md5=13edd939e0300dd88ea59df5d27aad8c&pid=1-s2.0-S2950117224000049-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142117415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coastal influence on microbiomes of the Southwest Atlantic Ocean","authors":"Cristiane C. Thompson ,&nbsp;Diogo Tschoeke ,&nbsp;Luciana Leomil ,&nbsp;Lucas Freitas ,&nbsp;Livia Vidal ,&nbsp;Koko Otsuki ,&nbsp;Claudia Omachi ,&nbsp;Igor M. Venâncio ,&nbsp;Yulin Zhang ,&nbsp;Jiwen Liu ,&nbsp;Xiao-Hua Zhang ,&nbsp;Ana Luiza S. Albuquerque ,&nbsp;Fabiano L. Thompson","doi":"10.1016/j.eve.2024.100048","DOIUrl":"10.1016/j.eve.2024.100048","url":null,"abstract":"<div><div>The possible influence of the continent on the microbiome of the Southwest Atlantic Ocean (SAO) is not yet fully known. The aim of the present study was to evaluate the metagenomic diversity of the SAO nearshore in different locations (e.g., rivers and upwellings) and offshore locations. The studied sites (n = 16) were clustered into four groups (G1-G4) according to the decadal sea surface temperature (SST) and levels of chlorophyll <em>a</em> (chl-a) (2007–2016). G1 (coastal upwelling) presented the highest chl-a values, G2 (shelf) had the highest SST, G3 (offshore north) had the lowest chl-a levels, and G4 (offshore south) was the coldest site. The higher nutrient levels may contribute to higher chl-a-based primary productivity and possibly higher bacterial productivity nearshore. The taxonomic and functional diversity of the total of 16 Illumina shotgun metagenomes were analysed (nearshore: 10, offshore: 6; mean ± standard deviation: 1.87 ± 0.41 million reads per sample). The SAO microbiomes were split into two groups: nearshore and offshore. The SAO coastal zone had higher abundance of picoplanktonic cyanobacteria (e.g., <em>Prochlorococcus</em>), copiotrophic bacteria (e.g., <em>Alteromonas</em>), chl-a photosynthesis, and metabolism of nitrogen and phosphorus. In clear contrast with offshore microbiomes, nearshore microbiomes were heterogenous as a possible effect of riverine runoff and the upwelling. G1 microbiomes had higher abundance of copiotrophic bacteria, while G2 had a higher abundance of <em>Prochlorococcus</em>, and G3 had a higher abundance of <em>Pelagibacter</em>. Offshore metagenomes (G3 and G4) had enrichment of proteorhodopsin light harvesting and sulfur metabolism, possible relevant processes in the SAO. Metagenome assembled genomes (MAGs) demonstrated significant novel microbiome diversity. The most abundant MAGs belong to <em>Flavobacteria</em> and <em>Euryarchaeota</em>. The discrimination of microbial populations and metabolisms in the four studied oceanographic groups provides a first glimpse on the microbial landscape in the SAO.</div></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"2 ","pages":"Article 100048"},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new model for Early Paleozoic ichnostratigraphy based on trace fossil assemblages from Brazil","authors":"Sara C. Memória ,&nbsp;Renata G. Netto ,&nbsp;Daniel Sedorko","doi":"10.1016/j.eve.2023.100026","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100026","url":null,"abstract":"<div><p>Trace fossils are not generally utilized as biostratigraphic indicators due to their long stratigraphic ranges. Despite the use of intricate behavioral traces in the absence of other indicators, existing models like the Precambrian–Cambrian boundary and <em>Cruziana</em> stratigraphy encounter limitations due to crucial data gaps and regional constraints. To surmount these challenges, in this paper, we critically assess established models and present a new framework for Early Paleozoic strata, drawing on trace fossils from the intracratonic basins of Brazil. Our ichnostratigraphic model is calibrated using ichnological data from the Parnaíba, Paraná, and Amazonas basins, including new data. The analysis focuses on trace fossils in strata that are independently dated using chitinozoan, miospore, and acritarch biozonation. Key ichnotaxa, such as <em>Arthrophycus</em> and <em>Cruziana</em>, are identified as prominent indicators of the Llandovery Stage in Brazil. Occurrences of <em>Heimdallia</em> and <em>Musculopodus</em> in the Tianguá Formation also may be used to suggest a Llandovery interval. Notably, <em>Bifungites</em>, found widely across Brazilian basins, emerges as a potential ichnomarker for the Early to mid-Paleozoic interval, with a global presence throughout Cambrian to Mississippian deposits. While current ichnostratigraphic models lack robust calibration with chronostratigraphic or biostratigraphic data, our new proposed model integrates key ichnotaxa, including <em>Bifungites, Climactichnites, Heimdallia, Oldhamia,</em> and <em>Musculopodus,</em> surpassing those pre-existing zonations based on <em>Cruziana</em> and arthrophycids. These ichnotaxa exhibit unique features and narrow temporal ranges, meeting essential biostratigraphic criteria. Although their spatial distribution is somewhat limited, our new model, which is continually evolving with new data, holds promise for enhancing global stratigraphic correlations, particularly where independent age information is available.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100026"},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000262/pdfft?md5=12d125104b48f332f032a9fe2454f873&pid=1-s2.0-S2950117223000262-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138471693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wildfire in the geological record: Application of Quaternary methods to deep time studies","authors":"Jennifer M. Galloway ,&nbsp;Sofie Lindström","doi":"10.1016/j.eve.2023.100025","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100025","url":null,"abstract":"<div><p>For hundreds of millions of years wildfire has influenced, and been influenced by, plant evolution, biogeochemical cycling, and climate. Wildfire has even been implicated as one of the causative agents of mass extinctions. The deep time geologic record offers demonstrated, but underdeveloped, potential to advance knowledge on the role of wildfire in the Earth system. Herein, we present and discuss the geologic history of wildfire and methods for its reconstruction. We argue that application of the numeric approaches to wildfire reconstruction often used in Quaternary studies would advance understanding of deep time wildfire. Application of numeric methods increases statistical rigour, with the intent of reducing bias and increasing accuracy. For example, numeric methods offer a means to robustly calibrate the provenance and taphonomy of particles used to reconstruct wildfire, and to quantify uncertainties. Statistical methods should be used to assess the fidelity of new chemical proxies of wildfire, such as the types, amounts, distributions, and isotope signatures of polycyclic aromatic hydrocarbons, to represent source area and fuel type.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100025"},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000250/pdfft?md5=37eac22344b5fb719505ff0d372425dd&pid=1-s2.0-S2950117223000250-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138475477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in Fe-redox and Fe-species across the end-Permian ‘Dead Zone’ in the Sydney Basin, Australia (252.10 ± 0.06 Ma): Evidence from X-ray absorption spectroscopy","authors":"Vivi Vajda ,&nbsp;Kajsa G.V. Sigfridsson Clauss ,&nbsp;Ashley Krüger ,&nbsp;Susan Nehzati","doi":"10.1016/j.eve.2023.100029","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100029","url":null,"abstract":"<div><p>The end-Permian mass extinction event is traceable across several non-marine basins in Australia. In the Sydney Basin, the lithological succession is characterized by a change from coal seams to mudstones and sandstones, recording a major environmental change following the disappearance of the Permian vegetation. A few millimeter-thick iron-rich ‘rusty’ layer occurs between the uppermost Permian coal seam and the mudstone, a layer that extends laterally across the basin and which has also been documented from coeval successions in Antarctica. This layer is overlain by the &lt;1.5-m-thick Frazer Beach Member, whose basal 10-cm-thick microbreccia bed comprises 99% kaolinite and quartz, and is dated as 252.10 ± 0.06 Ma. The Frazer Beach Member corresponds to the so-called end-Permian ‘Dead Zone’ lacking fossil pollen and leaves. This distinctive member was deposited directly following the extinction of the Permian peat-forming forests.</p><p>Here we identify, through X-ray absorption spectroscopy, a drastic redox shift across the extinction interval with increasing amount of reduced Fe-species followed by highly oxidized Fe-species, most resembling Fe(III) complexed with organic matter. Values subsequently normalise in younger samples through the ‘Dead Zone’, attaining only slightly higher redox-levels than before the event. The organically complexed Fe-species in the event bed is consistent with the standard Suwannee River fulvic acid, an acid Fe-complex with iron bound to organic matter, whereas the samples above and below the extinction layer yield spectra predominantly resembling magnetite (Fe₃O₄) mineral phase. We consider that the iron redox fluctuation marking the extinction interval is related to significant environmental changes with accumulation of organic matter following the mass extinction. The highly reduced iron in the extinction layer may relate to methane release from bacterial degradation, or emissions from clathrates. The presence of fulvic acid in the distinct iron-rich extinction layer indicates that an abrupt onset of the process of degradation of plant matter, lipids and calcium hydroxide (CaOH) took place, resulting in this ‘Death layer’. This was followed by millions of years of erosive conditions before new, complex vegetation could establish.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100029"},"PeriodicalIF":0.0,"publicationDate":"2023-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000298/pdfft?md5=b771f53898b8b63e7754f9d5211e45dc&pid=1-s2.0-S2950117223000298-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138435980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution and dynamics of the Arabian Sea oxygen minimum zone: Understanding the paradoxes","authors":"Arun Deo Singh ,&nbsp;Harshit Singh ,&nbsp;Shubham Tripathi ,&nbsp;Pradyumna Singh","doi":"10.1016/j.eve.2023.100028","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100028","url":null,"abstract":"<div><p>The Arabian Sea hosts a perennial and intense oxygen minimum zone (OMZ) at 150–1200 m depths with O₂ concentrations &lt;0.5 ml/l. It is generally believed that the oxygen-depleted conditions at mid-water depths result from high rate of O₂ consumption due to monsoon-driven productivity generating a high organic matter flux, combined with slow renewal of thermocline waters in the region. With global warming and increasing hypoxia, there is growing interest to better understand the various factors controlling oxygen conditions in the thermocline waters and the impact on the nutrient cycling and climate. In this contribution, we provide an overview of new advances in understanding the basin-wide changes of the OMZ, and highlight new perspectives on the relative roles of ocean and atmospheric circulations in modulating the OMZ intensity through the late glacial-Holocene period. Comprehension of the existing and new proxy records (δ¹⁵N, aragonite preservation, δ¹³C of benthic foraminifera) from the productive western and oligotrophic eastern and north-eastern Arabian Sea provides insights into the regional heterogeneity in basin-wide changes of the OMZ, denitrification and carbonate (aragonite) lysocline, and their links to the seasonal monsoon variability and reorganisation of thermocline circulation. We also highlight the limitations of the existing proxy data to address the important questions of how circulation and chemical properties of intermediate/deep water masses contributing to the Arabian Sea thermocline waters changed in the past. Hence, more detailed proxy data are required to characterise sources of water masses, past changes in their pathways and vertical extents in the Arabian Sea, which are crucial to better constrain the temporal evolution of thermocline ventilation basin-wide.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100028"},"PeriodicalIF":0.0,"publicationDate":"2023-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000286/pdfft?md5=cd7fab37d36de42b654a788a387b5f92&pid=1-s2.0-S2950117223000286-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138423298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}