Earth and Planetary Science Letters最新文献

{"title":"Prolonged sediment aggradation in an internal Himalayan valley due to out-of-sequence lateral fault growth","authors":"Vaishanavi Chauhan ,&nbsp;Sanjay Kumar Mandal ,&nbsp;Dirk Scherler ,&nbsp;Manoj Kumar Jaiswal ,&nbsp;Marcus Christl ,&nbsp;Anil D. Shukla","doi":"10.1016/j.epsl.2024.119054","DOIUrl":"10.1016/j.epsl.2024.119054","url":null,"abstract":"<div><div>Despite high rock uplift and surface runoff, most Himalayan river valleys feature tens of meters thick fill terraces, a legacy of aggradational episodes. Climate oscillations during the late Quaternary are commonly invoked to explain shifts from river incision to aggradation. While tectonic processes are known to cause transient aggradation, identifying their signatures and possible causes remains challenging. This study comprehensively analyzes ∼120-m thick valley-fill deposits exposed above the modern channel of the upper Beas River in the northwestern Indian Himalayan state of Himachal Pradesh. Luminescence dating of the valley fill reveals an aggradation period exceeding 100 kyr during the late Pleistocene, which likely commenced considerably earlier, based on an estimated &gt;400-m thick fill buried beneath the present valley floor. The prolonged aggradation, encompassing several glacial-interglacial cycles, and the absence of systematic changes in <figure><img></figure>Be-derived paleo-erosion rates or <figure><img></figure>Sr/<figure><img></figure>Sr and <figure><img></figure>Nd/<figure><img></figure>Nd isotope ratio-derived sediment provenance over time rule out late Quaternary climate oscillations as the sole driver of aggradation. Instead, we explain the longevity and extent of valley aggradation as the fluvial system's response to localized higher rock uplift rates downstream, as substantiated by the southern range flank morphology and the river network topology. We suggest that along-strike variations in thrust kinematics in this sector of the Himalaya likely caused the out-of-sequence lateral range growth and, consequently, triggered aggradation in the upstream valley. The implied temporal changes in stress and strain are critical for seismic hazard assessment.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119054"},"PeriodicalIF":4.8,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419377","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":"Correlating 300 million years of catastrophes","authors":"Alexei V. Ivanov","doi":"10.1016/j.epsl.2024.119058","DOIUrl":"10.1016/j.epsl.2024.119058","url":null,"abstract":"<div><div>It is frequently proposed that large bolide impacts and voluminous volcanic eruptions may be responsible for environmental catastrophes. In the conventional approach, the potential causes and consequences are matched using an age-versus-age plot, with preferential ages selected for comparison. This approach inevitably results in a one-to-one correlation, which may be misleading. To address this issue, a novel statistical metric, named conformity, has been proposed which accounts for the possibility of age coincidence resulting from random processes (i.e. bad luck coincidence). The available and updated geochronological datasets of bolide impacts, large igneous provinces, CO₂-concentration peaks in the atmosphere, mass extinctions, ocean anoxic events, and climatic optima and thermal highs were subjected to a comparison in terms of their concordance. The most significant discovery is the correlation between the ages of mass extinctions and those of giant bolide impacts (crater diameter &gt;40 km), as well as volcanism of continental large igneous provinces and CO₂-concentration peaks in the atmosphere. The severity of mass extinctions appears to be dependent upon the number of simultaneously occurring causes. The most pronounced Late Maastrichtian (∼66 Ma) and Changhsingian (∼252 Ma) mass extinctions were likely caused by a combination of factors, including the simultaneous occurrence of volcanism of continental large igneous provinces, giant bolide impact and CO₂-concentration rise in the atmosphere. Conversely, the ages of large igneous provinces, bolide impacts and CO₂-concentration peaks are not correlated, indicating that these three causes were not interdependent.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119058"},"PeriodicalIF":4.8,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420035","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":"Heterogeneous cooling subsidence of oceanic lithosphere controlled by spreading rate","authors":"Irina M. Artemieva","doi":"10.1016/j.epsl.2024.119017","DOIUrl":"10.1016/j.epsl.2024.119017","url":null,"abstract":"<div><div>Ocean age-dependent cooling subsidence with seafloor deepening is traditionally described by models of thermo-chemical buoyancy of oceanic plates with globally constant parameters, that specify a linear correlation between square-root of seafloor age, sqrt(age), and bathymetry. Here I present a worldwide analysis of the ocean floor split into 94 segments, delineated by wide-offset transform faults and mid-ocean ridges, to demonstrate a strong heterogeneity of sediment-corrected isostatic cooling subsidence both between and within normal oceans. Anomalous oceans are identified from bathymetry deviation from age-dependent predictions during data processing. Subsidence parameters for individual ocean segments significantly deviate from global constants in conventional models and show a large variability of subsidence rate (270–535 m/Ma^1/2) and zero-age depth (−1.30 to −3.03 km) with plate thickness estimated between 50 and 160 km for cooling models with constant mantle properties.</div><div>Statistically strong correlations (R²=0.80–0.94) between major characteristics of cooling subsidence and spreading rate indicate that ocean evolution is essentially controlled by spreading rate, despite this factor is not included in conventional models of ocean subsidence. Normal oceans with slower spreading rate have, statistically, higher subsidence rate which implies faster gravitational collapse caused by faster plate cooling with moderate-to-low mantle temperatures at mid-ocean ridges. Fast-spreading oceans have the opposite characteristics. The ultraslow SW Indian and the fast-spreading Central Pacific Oceans are the end-members in ocean cooling subsidence trends, with the Atlantic/NW Indian Oceans tending towards the ultraslow end, and the Pacific/SE Indian Oceans being closer to the fast-spreading end. The Arctic Ocean and the Atlantics north of the Charlie-Gibbs Fracture Zone with an atypical subsidence behavior often deviate from the global trends. Strong correlation between spreading rate, ocean half-width and the type of ocean margins implies that ridge-push dominates tectonic forces in slower-spreading, narrower oceans with passive margins, while slab-pull at active margins is a dominant tectonic force in faster-spreading oceans with half-width exceeding 4250 km.</div><div>The age of bathymetry departure from cooling subsidence, controlled by distribution of hotspots on ocean floor, correlates (R²=0.76) with spreading rate, and thus is not fully random. Slower-spreading oceans follow normal cooling subsidence to older ages (7.5–9.5 Ma^1/2) than faster-spreading oceans (5–7 Ma^1/2). Recognition that spreading rate controls ocean evolution with formation of active or passive ocean margins dominated by slab-pull or ridge-push contributes to advances in understanding driving forces in geodynamics.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119017"},"PeriodicalIF":4.8,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419322","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":"Control of stepwise subduction and slab breakoff on volcanism and uplift in the Tibetan Plateau","authors":"Jian Wang ,&nbsp;Zhi Wang ,&nbsp;Xiugen Fu ,&nbsp;Xuan-Ce Wang ,&nbsp;Simon A. Wilde ,&nbsp;Yi Fu ,&nbsp;Jian Lin ,&nbsp;Hengye Wei ,&nbsp;Lijun Shen ,&nbsp;Gang Rao ,&nbsp;Ahmed Mansour","doi":"10.1016/j.epsl.2024.119057","DOIUrl":"10.1016/j.epsl.2024.119057","url":null,"abstract":"<div><div>The Tibetan Plateau plays a crucial role in both Asian and global geomorphology and climate dynamics. However, the precise mechanisms through which its deep geodynamic processes influence surface systems have remained elusive. Here, we present a novel model that can be used to evaluate these processes, employing a comprehensive approach that incorporates multistage bilateral subduction, lithospheric breakoff, and subsequent foundering based on a combined analysis of global tomography, volcanic rock ages, and geochemical isotopes. By analyzing seismic tomography data derived from extensive seismic arrays recording over 18 million multi-phase arrival times, we have constrained the locations and morphology of remnant slabs associated with the subduction of the Neo-Tethyan Ocean, Greater Indian plate, and Asian lithosphere. Our findings reveal a striking correlation between discrete episodic surface volcanism and plate uplift at distinct intervals: 56–44 Ma, 44–28 Ma, 28–18 Ma, and 18–0 Ma within the Tibetan Plateau. These intervals correspond to four stages of stepwise lithospheric subduction. Paired slab-like anomalies observed during the second and third steps suggest simultaneous detachment of subducting lithosphere from opposing directions. Building upon this observation, we propose a two-sided breakoff model. This model posits that bilateral subduction and lithospheric gravitational subsidence have induced extensive volcanism and episodic uplift within the Tibetan Plateau. The subsidence, resulting from both past and ongoing lithospheric break-offs of the Indian and Asian plates, has triggered widespread volcanism that likely exerts a significant impact on climate patterns. Our study establishes a systematic framework linking deep lithospheric processes with surface phenomena in Tibet, providing valuable insights into the dynamic interactions shaping the region's geological and climatic evolution.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119057"},"PeriodicalIF":4.8,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419323","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":"Tracing the stepwise warming trend in the tropical Indian Ocean through a 40-year record of oxygen isotope composition in Maldives corals","authors":"Ke Lin ,&nbsp;Tao Han ,&nbsp;Kyle Morgan ,&nbsp;Paul S. Kench ,&nbsp;Yue-Gau Chen ,&nbsp;Xianfeng Wang","doi":"10.1016/j.epsl.2024.119025","DOIUrl":"10.1016/j.epsl.2024.119025","url":null,"abstract":"<div><div>Sea surface temperature (SST) across the tropical Indian Ocean is warming at a significantly higher rate than other tropical oceans over the past two decades. However, the cause of the abnormal warming remains unclear due to the short duration of instrumental observations as well as sparse long-term paleoclimate proxy records (e.g., from corals) within this region. Before coral-based records can be compiled to infer long-term environmental change in the region, an assessment of the suitability and robustness of the various coral archive types for evaluating warming must be made. Here, we present a 40-year coral stable oxygen isotopic ratio (δ¹⁸O) record derived from both dome-shaped (i.e., massive) and microatoll corals (<em>Porites</em> sp.) from the southern Maldives, located in the equatorial Indian Ocean. We found a consistent δ¹⁸O reproducibility in both dome-shaped and microatoll corals, demonstrating the viability of utilising a range of coral morphotypes for reconstructing long-term ocean conditions and climate change. Statistical analysis indicates that our coral δ¹⁸O values are primarily influenced by SST rather than sea surface salinity (SSS). Notably, the δ¹⁸O record exhibits a stepwise shift, with average δ¹⁸O values of -4.93 ‰ and -5.01 ‰ for the periods 1978–1999 and 2000–2019, respectively. This shift in δ¹⁸O corresponds with the increase in regional SST, despite its relatively small magnitude of approximately 0.3 °C. Furthermore, the negative shift in δ¹⁸O values after 2000 coincides with the transition to La Niña-like conditions and the negative Interdecadal Pacific Oscillation (IPO) phase in the tropical Pacific Ocean. Under these conditions, the geostrophic transport of the Indonesian Throughflow (ITF) was enhanced, which likely contributed to warming in the tropical Indian Ocean by bringing in more warm water from the Pacific. Therefore, the consistent shifts between our Maldives coral δ¹⁸O anomalies and instrumental SST anomalies support the argument that an intensified ITF may have contributed to the abnormal warming in the tropical Indian Ocean over the past two decades. Our findings suggest that microatoll corals in well-flushed open ocean environments can provide robust climatic proxy data comparable to dome-shaped corals. By compiling these records, we show the primary impact of SST on coral δ¹⁸O values in the tropical Indian Ocean, evidenced by a notable shift closely aligned with regional SST fluctuations around 2000.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119025"},"PeriodicalIF":4.8,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419376","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":"Bioavailability of molybdenite to support nitrogen fixation on early Earth by an anoxygenic phototroph","authors":"Xinyi Zhou ,&nbsp;Yizhi Sheng ,&nbsp;Yanning Zheng ,&nbsp;Mingyue Jiang ,&nbsp;Mengmei Wang ,&nbsp;Zihua Zhu ,&nbsp;Gaoyuan Li ,&nbsp;Oliver Baars ,&nbsp;Hailiang Dong","doi":"10.1016/j.epsl.2024.119056","DOIUrl":"10.1016/j.epsl.2024.119056","url":null,"abstract":"<div><div>Biological nitrogen fixation, which converts atmospheric dinitrogen to ammonia, is catalyzed mostly by Mo-nitrogenase and is a primary contributor to bioavailable nitrogen on early Earth. Mo-nitrogenase is believed to have evolved during the Archean, despite the extremely low concentration of dissolved Mo. However, it remains unclear whether Mo minerals could serve as a source of Mo to support the prevalence of Mo-nitrogenase on early Earth. Here we investigated the bioavailability of molybdenite by incubating it with a metabolically ancient anoxygenic phototroph (<em>Rhodopseudomonas palustris</em>) under anoxic conditions. In the laboratory, <em>R. palustris</em> utilized molybdenum from molybdenite as a cofactor for nitrogen fixation. This bacterium extracted Mo from molybdenite by secreting molybdophores rhodopetrobactin A and B and by expressing Mo transport proteins. Surface-sensitive techniques demonstrated significant changes in surface chemistry of molybdenite after its interaction with cells. These findings provide novel explanations for the prevalence of Mo-nitrogenase on early Earth, with significant implications for nitrogen fixation in modern Mo-deficient environments.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119056"},"PeriodicalIF":4.8,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419381","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":"From birth to death: The role of upper-crustal thermal maturation and volcanism in porphyry ore formation revealed in the Yerington district","authors":"Maria Paula Castellanos-Melendez ,&nbsp;John Dilles ,&nbsp;Marcel Guillong ,&nbsp;Olivier Bachmann ,&nbsp;Cyril Chelle-Michou","doi":"10.1016/j.epsl.2024.119053","DOIUrl":"10.1016/j.epsl.2024.119053","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The current race towards greener energy and its intertwined increase in Cu demand imposes the need to find mineralized centers that are economic despite greater depths. To this end, a better understanding of the processes controlling the metal tonnage of porphyry Cu deposits, the main source of Cu, is needed and the focus of current research and debate. This study provides a comprehensive view of the duration of upper-crustal magmatism and its significance in the degree of metal endowment in porphyry Cu deposits using the Yerington batholith, Nevada, USA, as a case study. The Yerington district constitutes an exceptional example of an exposed porphyry Cu system where the plutonic environment that fed the porphyritic dikes is accessible. Combining trace element geochemistry and high-precision geochronology of zircon from all exposed units, we propose that the thermal maturation of the upper crust by a continuum in magmatic activity without significant hiatuses is a key factor in enabling the formation of large porphyry Cu style mineralization. The Yerington magmatic system transitioned from a volcanically active environment with coeval plutonism to a growing upper-crustal magmatic reservoir that fed the porphyritic dikes and associated mineralized centers to then resume its volcanic activity terminating the ore-forming episode. A relatively high volcanic/plutonic ratio characterized the first expressions of Jurassic magmatism in the district from ∼170 Ma with the coeval eruption of the Artesia Lake volcanics and the protracted emplacement of the McLeod Hill pluton. Geochemically, this period recorded distinctive negative Eu anomalies and a gentle increase in Yb/Dy ratios in zircon with decreasing Ti contents over a large range of zircon crystallization temperatures. This persistent magmatism over ∼2 Myr thermally matured the upper crust, enabling the growth of magmatic reservoirs that formed the Bear and Luhr Hill plutons without known volcanic activity for ∼1.3 Myr. Zircon trace element compositions indicate that this transition occurred as a continuum in decreasing negative Eu anomalies and increasing Yb/Dy with decreasing Ti contents and age across the plutonic units, reaching the more evolved signatures and lowest crystallization temperatures in the zircon from porphyry dikes. An increase in the volcanic/plutonic ratio with the eruption of the Fulstone Spring sequence likely terminated the ore-forming potential of the district. Although many other studies have provided important views on the timing and duration of porphyry Cu deposit formation, the link to their plutonic roots has been limited due to their inaccessibility. Therefore, this study offers the first complete picture into the temporal and chemical evolution of an upper-crustal magmatic system and the roles that factors like prolonged magmatism and volcanism play before and after ore formation. We argue that without the thermal maturation of the upper crust, the constructio","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119053"},"PeriodicalIF":4.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419320","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":"Composition and age constraints on a Hadean enriched mantle source revealed by the Paleoarchean São Tomé layered intrusion, NE Brazil","authors":"V.B. Garcia ,&nbsp;J. O'Neil ,&nbsp;E.L. Dantas ,&nbsp;C.T. Augustin","doi":"10.1016/j.epsl.2024.119051","DOIUrl":"10.1016/j.epsl.2024.119051","url":null,"abstract":"<div><div>Evidence for Hadean depleted mantle reservoir(s) is well-established by mantle-derived rocks from multiple Archean complexes showing excesses in ¹⁴²Nd compared to the modern mantle. Yet, the existence of an early enriched mantle source, which should have concomitantly formed during these Hadean silicate differentiation event(s), has only been recently confirmed by well-resolved ¹⁴²Nd deficits measured in Paleoarchean mafic amphibolites from the São José do Campestre massif of the Borborema Province, NE Brazil. To investigate the nature and extent of this early-formed enriched reservoir, a series of samples from the Seridó belt, NE Brazil, have been investigated for their geochemical and coupled ^147,146Sm-^143,142Nd isotopic compositions, focusing on the Paleoarchean São Tomé layered intrusion. The São Tomé intrusion is composed of layers of metamorphosed mafic and ultramafic rocks with whole-rock trace element compositions and high olivine crystal Ni contents consistent with an incompatible trace element enriched pyroxenitic mantle source. Most analyzed samples from the Seridó belt yielded negative µ¹⁴²Nd, as low as ∼ -20 (representing the lowest ¹⁴²Nd/¹⁴⁴Nd ratio ever measured in terrestrial rocks), with an average µ¹⁴²Nd for the São Tomé intrusion of -9.6 ± 1.4. The São Tomé samples interpreted as the least isotopically disturbed yielded an ¹⁴⁷Sm-¹⁴³Nd isochron age of 3551 ± 368 Ma, consistent with previous zircon U-Pb ages, with an initial ε¹⁴³Nd = -1.7 ± 1.2. Coupling the long-lived ¹⁴⁷Sm-¹⁴³Nd and the short-lived ¹⁴⁶Sm-¹⁴²Nd systems for the São Tomé rocks suggests a Hadean enriched mantle source formed at ∼4.44 Ga with a ¹⁴⁷Sm/¹⁴⁴Nd of ∼0.18, which may be complementary to the early depleted mantle recorded by Eoarchean rocks from the North Atlantic Craton, possibly formed during magma ocean crystallization. These results also imply that the record of this Hadean enriched mantle source is not restricted to the São José do Campestre massif but extends to a larger portion of the Borborema Province.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119051"},"PeriodicalIF":4.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419319","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":"Dynamic evolution of competing same-dip double subduction: New perspectives of the Neo-Tethyan plate tectonics","authors":"Arnab Roy ,&nbsp;Nibir Mandal ,&nbsp;Jeroen Van Hunen","doi":"10.1016/j.epsl.2024.119032","DOIUrl":"10.1016/j.epsl.2024.119032","url":null,"abstract":"<div><div><em>Same-dip double-subduction</em> (SDDS) systems are widely reported from present as well as past complex convergent plate tectonic configurations. However, the dynamics of their evolution is poorly understood, which is crucial to conceptualize anomalous subducting slab kinematics and associated observed geological phenomena, such as irregular trench migration rates, high convergence velocities, and slab break-off. To bridge this gap, we develop dynamic thermo-mechanical subduction models and investigate the initiation and evolution of SDDS systems, considering three different initial plate configurations: oceanic, oceanic-continental and multiple continental settings, based on Neo-Tethyan paleo-reconstructions. Each model offers new insights into the complex tectonic history of the major Neo-Tethyan subduction zones, particularly the Indo–Eurasian and Andaman convergent systems. We evaluate the slab-slab interactions, trench and subduction kinematics, inter-plate reorganization, and temporally varying mantle flow patterns involved in the dynamic evolution of these SDDS systems. The oceanic SDDS model simulations reveal that a sizable oceanic plate can initiate two subduction zones synchronously, and they evolve unequally in a competing mode, leading to exceptionally high convergence rates (∼16–17 cm/year) for a prolonged duration (∼7–8 Myr). This finding explains the coeval activity of coupled subduction zones in the Indo-Eurasia convergence during the Cretaceous evolution of the Neo-Tethys. We further implement a corresponding single subduction model to assess the additional effects of competing slab kinematics in an oceanic SDDS setting. The ocean-continent SDDS model, on the other hand, localizes subduction preferentially at passive margins between the oceanic plate and the continental block, forming double subduction zones that grow almost equally to form a spreading centre between the two trenches. These model results allow to reconstruct the Cenozoic evolution of the eastern Neo-Tethyan region, which ultimately led to the development of the Andaman subduction zone. We also show the post-Cretaceous evolution of the Indo–Eurasian collision zone as a consequence of the SDDS dynamics in presence of multiple continental blocks. These dynamics facilitated slab break-off, transforming the SDDS into a single subduction system in a relatively short time frame (∼3 Myr). We finish with a synthesis of the paleo-reconstructions of the Neo-Tethys in the perspective of these SDDS models.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119032"},"PeriodicalIF":4.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419321","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":"Magnetotelluric evidence for the formation of the layered Sask Craton by flat slab subduction","authors":"B.F.W. Chase,&nbsp;M.J. Unsworth","doi":"10.1016/j.epsl.2024.119027","DOIUrl":"10.1016/j.epsl.2024.119027","url":null,"abstract":"<div><div>Long-period magnetotelluric (MT) data were collected at 56 locations over the Sask Craton in 2021 and 2022. The data were combined with existing broadband data and inverted to produce a 3-D resistivity model of the Sask Craton and Trans-Hudson Orogen (THO). The model reveals a number of northeast striking electrically conductive crustal structures that extend into the mantle lithosphere. In the mantle lithosphere, these conductors coalesce into a single large low resistivity anomaly in the depth range 70–85 km termed the Northern Sask Craton (NSC) conductor. The resistivity of the NSC conductor is attributed to sulfides deposited along an interface between a flat slab that was accreted to the base of the pre-THO Sask Craton lithosphere during closure of the Manikewan Ocean. Kimberlites have erupted along the margin of the NSC conductor. The boundary of the conductor likely represents deep-seated faults and mantle terrane boundaries formed during flat slab subduction that allowed the ascent of kimberlite melts. The resistivity of the northeast-trending conductors can be interpreted as due to graphite and sulfides precipitated by past fluid or melt flow during ocean closure and orogensis. A number of these conductors are located beneath known mineral districts and trends and may represent source pathways for regional base and precious metal deposits. Other conductors may represent possible, previously unknown, regions hosting mineralization. Many of these conductors are associated with major regional faults and shear zones, which may be deep-seated features that helped to guide both kimberlites and mineralizing fluids. Of the prominent northeast-trending conductors west of the Sask Craton, one corresponds to the previously reported North American Central Plains (NACP) conductor. The new model shows that this conductor abruptly terminates at 54 °N and is not observed farther south in the model. This shows that the NACP is not as spatially continuous as previously suggested, suggesting that the tectonic processes that formed the THO were not as uniform along-strike as shown in existing tectonic models. The connection of one of the northeast-trending anomalies to the NSC conductor suggests that a previously unrecognized phase of east-dipping subduction may have occurred beneath the Sask Craton as the THO was formed.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119027"},"PeriodicalIF":4.8,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419316","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}