Carbonatites are magmatic rocks that host most economic rare earth element (REE) deposits and bear on the deep Earth volatile cycle. Yet, the cumulative character of plutonic carbonatites and the rapid posteruptive alteration of volcanic carbonatites impede a direct determination of the melt compositions crystallizing these rocks. This study focused on sodium in carbonatite melts, a critical component for their genesis, magmatic evolution, and also for REE mobility, given that most carbonatite-hosted REE mineralizations are formed by alkali-rich fluids. Through experiments at subvolcanic conditions (100−200 MPa, 800−1000 °C), we determined the partition coefficient of Na between apatite and carbonatite melt, DNaapatite/carbonatite, which is rather uniformly 0.010 ± 0.003 at temperatures ≥800 °C. Applying our DNaapatite/carbonatite value to natural samples yields 8−22 wt% Na2O for the melts forming calcic carbonatites and 26−32 wt% Na2O for melts forming dolomite carbonatites. The latter are hence more evolved than calcic carbonatite melts, increasing their potential to shed alkali-rich fluids. A model accounting for calcite fractionation from calcite carbonatite melts prior to apatite saturation indicates primary Na2Omelt contents of 16−23 wt% at 900 °C and 9−11 wt% at 1100 °C, consistent with formation by liquid immiscibility from alkaline silicate magmas, but inconsistent with direct mantle derivation, in particular for dolomitic melts.
{"title":"Sodic nature of carbonatite melts and the origin of calcite versus dolomite carbonatites","authors":"Simone Marioni, Gino Sartori, Max W. Schmidt","doi":"10.1130/g53916.1","DOIUrl":"https://doi.org/10.1130/g53916.1","url":null,"abstract":"Carbonatites are magmatic rocks that host most economic rare earth element (REE) deposits and bear on the deep Earth volatile cycle. Yet, the cumulative character of plutonic carbonatites and the rapid posteruptive alteration of volcanic carbonatites impede a direct determination of the melt compositions crystallizing these rocks. This study focused on sodium in carbonatite melts, a critical component for their genesis, magmatic evolution, and also for REE mobility, given that most carbonatite-hosted REE mineralizations are formed by alkali-rich fluids. Through experiments at subvolcanic conditions (100−200 MPa, 800−1000 °C), we determined the partition coefficient of Na between apatite and carbonatite melt, DNaapatite/carbonatite, which is rather uniformly 0.010 ± 0.003 at temperatures ≥800 °C. Applying our DNaapatite/carbonatite value to natural samples yields 8−22 wt% Na2O for the melts forming calcic carbonatites and 26−32 wt% Na2O for melts forming dolomite carbonatites. The latter are hence more evolved than calcic carbonatite melts, increasing their potential to shed alkali-rich fluids. A model accounting for calcite fractionation from calcite carbonatite melts prior to apatite saturation indicates primary Na2Omelt contents of 16−23 wt% at 900 °C and 9−11 wt% at 1100 °C, consistent with formation by liquid immiscibility from alkaline silicate magmas, but inconsistent with direct mantle derivation, in particular for dolomitic melts.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"56 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807416","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}
Luoqi Wang, Tianyi Li, Sensen Wu, Jie Yang, Yanhua Hu, Linshu Hu, Yijun Chen, YunZhao Ge, Yunfeng Chen, Can Rao, Zhenhong Du
The discovery and development of mineral resources are critical for sustaining modern energy demands. However, the geological processes that control mineralization are inherently complex, introducing considerable spatial variability that presents significant challenges for predictive modeling. While machine learning approaches have been increasingly applied to mineral prospectivity, many fail to explicitly incorporate key geological constraints, limiting their capacity to resolve the nonlinear and directionally dependent nature of mineralizing systems. Here we present a geologically constrained data-driven method that explicitly accounts for the spatial non-stationarity and anisotropy in ore-forming processes. In the benchmark case study from Canada, our method demonstrates a 7.4% improvement in recall performance compared with existing models. This robust performance is also observed in applications to the southern Cordillera region. Furthermore, the method elucidates regional ore-forming controls and quantifies spatial anisotropy in porphyry copper systems. Our findings demonstrate that incorporating geological constraints into data-driven models enhances both the accuracy and interpretability of mineral prospectivity assessments, offering a robust path forward in resource exploration.
{"title":"Geologically constrained data-driven modeling for mineral prospectivity mapping","authors":"Luoqi Wang, Tianyi Li, Sensen Wu, Jie Yang, Yanhua Hu, Linshu Hu, Yijun Chen, YunZhao Ge, Yunfeng Chen, Can Rao, Zhenhong Du","doi":"10.1130/g53947.1","DOIUrl":"https://doi.org/10.1130/g53947.1","url":null,"abstract":"The discovery and development of mineral resources are critical for sustaining modern energy demands. However, the geological processes that control mineralization are inherently complex, introducing considerable spatial variability that presents significant challenges for predictive modeling. While machine learning approaches have been increasingly applied to mineral prospectivity, many fail to explicitly incorporate key geological constraints, limiting their capacity to resolve the nonlinear and directionally dependent nature of mineralizing systems. Here we present a geologically constrained data-driven method that explicitly accounts for the spatial non-stationarity and anisotropy in ore-forming processes. In the benchmark case study from Canada, our method demonstrates a 7.4% improvement in recall performance compared with existing models. This robust performance is also observed in applications to the southern Cordillera region. Furthermore, the method elucidates regional ore-forming controls and quantifies spatial anisotropy in porphyry copper systems. Our findings demonstrate that incorporating geological constraints into data-driven models enhances both the accuracy and interpretability of mineral prospectivity assessments, offering a robust path forward in resource exploration.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"23 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807827","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}
Eva E. Stüeken, Anthony R. Prave, Liam O’Connor, Jonas Kaempf, Anthony Clarke, Tim E. Johnson, Christopher L. Kirkland
Stromatolites are indicators of life on Earth since at least 3.5 Ga and possibly 3.7 Ga. From the mid-Archean onward, records of stromatolites display a range of morphologies and sizes, indicating that microorganisms were present in a variety of habitats. By comparison, the existing Paleoarchean stromatolite record is limited to small decimeter-scale domes, cones, and tufts that occur in evaporitic environments. Here, we document large domal stromatolites with ∼1.5 m width and 0.8 m height from a chert-jasper-carbonate member in the Paleoarchean (ca. 3.47 Ga) Mount Ada Basalt, Pilbara craton, Western Australia. Sedimentological features and trace-element chemistry show that the stromatolites grew on seafloor pillow basalts in an anoxic environment with hydrothermal influence. Aqueous alteration of basaltic-komatiitic crust likely supplied key nutrients, extending benthic microbial habitats into the deeper Paleoarchean ocean and supporting a thriving biosphere independent of continental exposure.
{"title":"Large domal stromatolites in the Paleoarchean ocean at 3.47 Ga","authors":"Eva E. Stüeken, Anthony R. Prave, Liam O’Connor, Jonas Kaempf, Anthony Clarke, Tim E. Johnson, Christopher L. Kirkland","doi":"10.1130/g53960.1","DOIUrl":"https://doi.org/10.1130/g53960.1","url":null,"abstract":"Stromatolites are indicators of life on Earth since at least 3.5 Ga and possibly 3.7 Ga. From the mid-Archean onward, records of stromatolites display a range of morphologies and sizes, indicating that microorganisms were present in a variety of habitats. By comparison, the existing Paleoarchean stromatolite record is limited to small decimeter-scale domes, cones, and tufts that occur in evaporitic environments. Here, we document large domal stromatolites with ∼1.5 m width and 0.8 m height from a chert-jasper-carbonate member in the Paleoarchean (ca. 3.47 Ga) Mount Ada Basalt, Pilbara craton, Western Australia. Sedimentological features and trace-element chemistry show that the stromatolites grew on seafloor pillow basalts in an anoxic environment with hydrothermal influence. Aqueous alteration of basaltic-komatiitic crust likely supplied key nutrients, extending benthic microbial habitats into the deeper Paleoarchean ocean and supporting a thriving biosphere independent of continental exposure.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"185 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807826","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}
Giovanni Camanni, Efstratios Delogkos, Stefano Tavani, Ester Piegari, Muhammed Kösen
The reactivation of deep-seated, throughgoing strike-slip faults produces highly segmented fault zones at shallower levels, yet how displacement is partitioned among segments as the fault grows remains poorly constrained. We address this by examining a ∼160-m-long section of the East Anatolian fault surface rupture of the Mw 7.8 2023 Kahramanmaraş strike-slip earthquake (Turkey). The rupture offsets meter-spaced ridges and furrows in a ploughed field, providing a unique opportunity for detailed displacement measurements, which were obtained from an orthophoto and a digital elevation model (DEM) built for this study. The surface rupture consists of ten primary segments separated by nine restraining stepovers and is associated with a 3-D strain field dominated by ∼3.5 m of left-lateral offset. Displacement patterns allow us to derive a new model for strike-slip fault growth in which deformation is asymmetric and controlled by the 3-D structure of the fault—specifically, by the position of the underlying fault relative to shallow fault segments. Initially, displacement is accommodated by contraction within restraining stepovers. With increasing displacement, fault segments located closer to the trace of the underlying fault consistently accumulate greater displacement. This asymmetry is facilitated by enhanced synthetic rotation within stepovers. With further displacement, the higher-displacement segment bounding a stepover becomes dominant, while the other one is bypassed and layer rotation ceases. These results not only improve fault growth models but could also inform seismic hazard models and impact industrial applications dealing with subsurface faulted reservoirs.
{"title":"Asymmetric growth of strike-slip faults controlled by 3-D fault structure: Insights from the Mw 7.8 2023 Kahramanmaraş (Turkey) earthquake","authors":"Giovanni Camanni, Efstratios Delogkos, Stefano Tavani, Ester Piegari, Muhammed Kösen","doi":"10.1130/g53724.1","DOIUrl":"https://doi.org/10.1130/g53724.1","url":null,"abstract":"The reactivation of deep-seated, throughgoing strike-slip faults produces highly segmented fault zones at shallower levels, yet how displacement is partitioned among segments as the fault grows remains poorly constrained. We address this by examining a ∼160-m-long section of the East Anatolian fault surface rupture of the Mw 7.8 2023 Kahramanmaraş strike-slip earthquake (Turkey). The rupture offsets meter-spaced ridges and furrows in a ploughed field, providing a unique opportunity for detailed displacement measurements, which were obtained from an orthophoto and a digital elevation model (DEM) built for this study. The surface rupture consists of ten primary segments separated by nine restraining stepovers and is associated with a 3-D strain field dominated by ∼3.5 m of left-lateral offset. Displacement patterns allow us to derive a new model for strike-slip fault growth in which deformation is asymmetric and controlled by the 3-D structure of the fault—specifically, by the position of the underlying fault relative to shallow fault segments. Initially, displacement is accommodated by contraction within restraining stepovers. With increasing displacement, fault segments located closer to the trace of the underlying fault consistently accumulate greater displacement. This asymmetry is facilitated by enhanced synthetic rotation within stepovers. With further displacement, the higher-displacement segment bounding a stepover becomes dominant, while the other one is bypassed and layer rotation ceases. These results not only improve fault growth models but could also inform seismic hazard models and impact industrial applications dealing with subsurface faulted reservoirs.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"36 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807417","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}
Lidya G. Tarhan, Thomas H. Boag, Boriana Kalderon-Asael
The Ediacara Biota—Earth’s earliest fossilized ecosystems of complex, macroscopic organisms—has played a key role in shaping understanding of the transition between the Precambrian and early Paleozoic radiations of animal diversity. The majority of Ediacara Biota Lagerstätten are exceptionally preserved in the distinctive Ediacara style as three-dimensional casts and molds in sandstones. However, the factors responsible for the fossilization of these soft-bodied organisms—in particular, for their preservation in compositionally immature sandstones and heterolithic strata—remain debated. In this study, we investigate the taphonomic importance of clay minerals in fostering Ediacara-style fossilization in classic Ediacara Biota fossil assemblages in Newfoundland and northwestern Canada. Using a combination of electron microscopy, X-ray diffraction, and major and trace element and lithium isotope analyses, we describe evidence for both detrital and early diagenetic clay minerals associated with these fossils. In particular, we document iron- and magnesium-rich clays, including chamosite and other chlorite-group minerals, which may reflect an authigenic precursor such as berthierine, a mineral that has also been implicated in other modes of exceptional preservation. Lithium isotope data corroborate the importance of detrital and marine authigenic clays in shaping the moldic preservation of these fossils. These results provide a broader view of potential drivers of the Ediacara-style fossil record and suggest that authigenic clay mineralization may have shaped multiple windows of exceptional fossilization across the Neoproterozoic−Paleozoic transition.
{"title":"Authigenic clays shaped Ediacara-style exceptional fossilization","authors":"Lidya G. Tarhan, Thomas H. Boag, Boriana Kalderon-Asael","doi":"10.1130/g53967.1","DOIUrl":"https://doi.org/10.1130/g53967.1","url":null,"abstract":"The Ediacara Biota—Earth’s earliest fossilized ecosystems of complex, macroscopic organisms—has played a key role in shaping understanding of the transition between the Precambrian and early Paleozoic radiations of animal diversity. The majority of Ediacara Biota Lagerstätten are exceptionally preserved in the distinctive Ediacara style as three-dimensional casts and molds in sandstones. However, the factors responsible for the fossilization of these soft-bodied organisms—in particular, for their preservation in compositionally immature sandstones and heterolithic strata—remain debated. In this study, we investigate the taphonomic importance of clay minerals in fostering Ediacara-style fossilization in classic Ediacara Biota fossil assemblages in Newfoundland and northwestern Canada. Using a combination of electron microscopy, X-ray diffraction, and major and trace element and lithium isotope analyses, we describe evidence for both detrital and early diagenetic clay minerals associated with these fossils. In particular, we document iron- and magnesium-rich clays, including chamosite and other chlorite-group minerals, which may reflect an authigenic precursor such as berthierine, a mineral that has also been implicated in other modes of exceptional preservation. Lithium isotope data corroborate the importance of detrital and marine authigenic clays in shaping the moldic preservation of these fossils. These results provide a broader view of potential drivers of the Ediacara-style fossil record and suggest that authigenic clay mineralization may have shaped multiple windows of exceptional fossilization across the Neoproterozoic−Paleozoic transition.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"161 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765170","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}
Rocio Jaimes-Gutierrez, Lucas Vimpere, David J. Wilson, Patrick Blaser, Philip A.E. Pogge von Strandmann, Thierry Adatte, Swapan Sahoo, Sébastien Castelltort
Silicate weathering regulates Earth’s long-term climate by removing atmospheric CO2. Understanding changes in weathering regimes and rates is key to predicting climate response time scales. We investigated the reactivity of the North American source-to-sink system and the chemical weathering regime during the Paleocene−Eocene Thermal Maximum (PETM). We measured the detrital lithium isotope composition (δ7Li) in a deep-marine sediment core from the Gulf of Mexico, tracking changes in the formation of clay minerals, alongside neodymium isotopes (εNd), to constrain sediment provenance. We find a buffered negative δ7Li excursion during the PETM body, likely reflecting the mixing of neoformed and reworked clays from continental floodplains, followed by a stronger negative δ7Li excursion during the recovery phase. This pattern aligns with the continental Bighorn Basin (Wyoming, USA) δ7Li record, indicating rapid propagation of enhanced weathering and erosion fluxes in response to the PETM, which would have contributed to efficient CO2 drawdown.
{"title":"Lithium isotopes reveal enhanced weathering fluxes in North America during the Paleocene−Eocene Thermal Maximum","authors":"Rocio Jaimes-Gutierrez, Lucas Vimpere, David J. Wilson, Patrick Blaser, Philip A.E. Pogge von Strandmann, Thierry Adatte, Swapan Sahoo, Sébastien Castelltort","doi":"10.1130/g53708.1","DOIUrl":"https://doi.org/10.1130/g53708.1","url":null,"abstract":"Silicate weathering regulates Earth’s long-term climate by removing atmospheric CO2. Understanding changes in weathering regimes and rates is key to predicting climate response time scales. We investigated the reactivity of the North American source-to-sink system and the chemical weathering regime during the Paleocene−Eocene Thermal Maximum (PETM). We measured the detrital lithium isotope composition (δ7Li) in a deep-marine sediment core from the Gulf of Mexico, tracking changes in the formation of clay minerals, alongside neodymium isotopes (εNd), to constrain sediment provenance. We find a buffered negative δ7Li excursion during the PETM body, likely reflecting the mixing of neoformed and reworked clays from continental floodplains, followed by a stronger negative δ7Li excursion during the recovery phase. This pattern aligns with the continental Bighorn Basin (Wyoming, USA) δ7Li record, indicating rapid propagation of enhanced weathering and erosion fluxes in response to the PETM, which would have contributed to efficient CO2 drawdown.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"3 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145746673","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}
Tülay Kaya-Eken, Yasuo Ogawa, Yoshiya Usui, Takafumi Kasaya, M. Kemal Tunçer, Yoshimori Honkura, Naoto Oshiman, Masaki Matsushima, Weerachai Siripunvaraporn
Reliable knowledge of the crustal properties beneath the North Anatolian fault (NAF), seismically silent for more than 250 years beneath the Marmara Sea (MS), is crucial for understanding seismic hazard and mitigating the potential for disaster on an enormous scale. In the present work, the first three-dimensional inverse modeling performed on a magnetotelluric dataset of the MS has unveiled localized weak and locked fault segments along this shear deformation zone. Low-resistivity regions along the northern branch of the NAF beneath the Central and Çınarcık-Imralı basins are likely attributed to the presence of fluids, which may represent a fault zone conductor in a fractured zone and can explain the densely populated microseismicity. These low-resistivity anomalies surrounded by higher resistivity structures imply that the segmented, multi-branched NAF system extends beneath the MS, following the Intra-Pontide suture zone. The resistive anomalies, between the Central and Çınarcık basins, along with those at the western and eastern extremities of the MS, presumably signify regions of stress accumulation, shedding light on the ongoing processes of fault mechanics at play in this critical region.
{"title":"3-D electromagnetic imaging of highly deformed fluid-rich weak zones and locked section of the North Anatolian fault beneath the Marmara Sea","authors":"Tülay Kaya-Eken, Yasuo Ogawa, Yoshiya Usui, Takafumi Kasaya, M. Kemal Tunçer, Yoshimori Honkura, Naoto Oshiman, Masaki Matsushima, Weerachai Siripunvaraporn","doi":"10.1130/g52995.1","DOIUrl":"https://doi.org/10.1130/g52995.1","url":null,"abstract":"Reliable knowledge of the crustal properties beneath the North Anatolian fault (NAF), seismically silent for more than 250 years beneath the Marmara Sea (MS), is crucial for understanding seismic hazard and mitigating the potential for disaster on an enormous scale. In the present work, the first three-dimensional inverse modeling performed on a magnetotelluric dataset of the MS has unveiled localized weak and locked fault segments along this shear deformation zone. Low-resistivity regions along the northern branch of the NAF beneath the Central and Çınarcık-Imralı basins are likely attributed to the presence of fluids, which may represent a fault zone conductor in a fractured zone and can explain the densely populated microseismicity. These low-resistivity anomalies surrounded by higher resistivity structures imply that the segmented, multi-branched NAF system extends beneath the MS, following the Intra-Pontide suture zone. The resistive anomalies, between the Central and Çınarcık basins, along with those at the western and eastern extremities of the MS, presumably signify regions of stress accumulation, shedding light on the ongoing processes of fault mechanics at play in this critical region.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"34 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704187","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}
Kemi Ashing-Giwa, Jonathan L. Payne, Erik A. Sperling
In the wake of the end-Permian mass extinction, bivalves replaced articulate brachiopods as the dominant benthic marine filter-feeders, despite morphological and ecological similarities. Several factors have been suggested as drivers of the extinction’s selectivity, including competition, ocean acidity, CO2 poisoning, and differing reproductive potential. The spread of sulfidic water (euxinia) has been proposed as a general kill mechanism, but its physiological selectivity has not been investigated. Survival studies of the co-occurring bivalve Glycymeris septentrionalis and articulate brachiopod Terebratalia transversa from San Juan Island, Washington, USA, were carried out in anoxic and euxinic environments at 13.7, 16, and 22 °C. In colder anoxic conditions without sulfide, the brachiopod exhibited greater survival than the bivalve, but at higher temperatures, the bivalve generally outlasted the brachiopod, and by a greater margin in euxinia. The alignment between physiological tolerance in experimental settings and survival patterns in the paleontological record indicates that euxinia may have played a role in end-Permian extinction severity and selectivity, serving as an additional stressor in already warm, oxygen-depleted oceans.
{"title":"Investigating the response of Glycymeris septentrionalis (Bivalvia) and Terebratalia transversa (Brachiopoda) to euxinia: Implications for mass extinctions","authors":"Kemi Ashing-Giwa, Jonathan L. Payne, Erik A. Sperling","doi":"10.1130/g53911.1","DOIUrl":"https://doi.org/10.1130/g53911.1","url":null,"abstract":"In the wake of the end-Permian mass extinction, bivalves replaced articulate brachiopods as the dominant benthic marine filter-feeders, despite morphological and ecological similarities. Several factors have been suggested as drivers of the extinction’s selectivity, including competition, ocean acidity, CO2 poisoning, and differing reproductive potential. The spread of sulfidic water (euxinia) has been proposed as a general kill mechanism, but its physiological selectivity has not been investigated. Survival studies of the co-occurring bivalve Glycymeris septentrionalis and articulate brachiopod Terebratalia transversa from San Juan Island, Washington, USA, were carried out in anoxic and euxinic environments at 13.7, 16, and 22 °C. In colder anoxic conditions without sulfide, the brachiopod exhibited greater survival than the bivalve, but at higher temperatures, the bivalve generally outlasted the brachiopod, and by a greater margin in euxinia. The alignment between physiological tolerance in experimental settings and survival patterns in the paleontological record indicates that euxinia may have played a role in end-Permian extinction severity and selectivity, serving as an additional stressor in already warm, oxygen-depleted oceans.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"5 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704186","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}
Bryan A. Black, Patrick T. Pringle, James W. Vallance
New dating of lahar-killed trees underscores volcano hazards in the Puget Sound metropolitan area. Beginning as a landslide from the west flank of Mount Rainier, Washington, USA, the Electron Mudflow, which was the largest lahar of the last millennium, swept more than 60 km down the Puyallup River drainage into areas now densely populated. Wiggle matching of seven radiocarbon ages from buried, bark-bearing Douglas-fir (Pseudotsuga menziesii) trees brackets the mudflow’s age between 1477 and 1522 CE with 99.7% certainty. To narrow this date, we applied dendrochronology crossdating on samples collected from 21 trees killed by the lahar, measuring 86 time series for statistical verification. The four bark-bearing trees died the same year while the final rings in all other trees had decayed, exposing rings formed in earlier years. When averaged together, the crossdated measurements form a 475 yr master chronology that was correlated against absolutely dated tree-ring chronologies in the region. The Electron chronology best matched with chronologies from low-elevation sites, especially a Douglas-fir chronology from Vancouver Island, Canada, to show that the Electron trees died in 1507 CE. Latewood in the final ring was beginning to form, indicating the mudflow likely occurred in the late-summer months. What caused the Electron Mudflow is unknown, but this precise date will help to assess possible relationships with other events, assist in interpreting Indigenous narratives about the mudflow, and increase awareness of potential lahar hazards.
{"title":"Forest-floor burial in 1507 by the largest Mount Rainier lahar of the past millennium","authors":"Bryan A. Black, Patrick T. Pringle, James W. Vallance","doi":"10.1130/g53721.1","DOIUrl":"https://doi.org/10.1130/g53721.1","url":null,"abstract":"New dating of lahar-killed trees underscores volcano hazards in the Puget Sound metropolitan area. Beginning as a landslide from the west flank of Mount Rainier, Washington, USA, the Electron Mudflow, which was the largest lahar of the last millennium, swept more than 60 km down the Puyallup River drainage into areas now densely populated. Wiggle matching of seven radiocarbon ages from buried, bark-bearing Douglas-fir (Pseudotsuga menziesii) trees brackets the mudflow’s age between 1477 and 1522 CE with 99.7% certainty. To narrow this date, we applied dendrochronology crossdating on samples collected from 21 trees killed by the lahar, measuring 86 time series for statistical verification. The four bark-bearing trees died the same year while the final rings in all other trees had decayed, exposing rings formed in earlier years. When averaged together, the crossdated measurements form a 475 yr master chronology that was correlated against absolutely dated tree-ring chronologies in the region. The Electron chronology best matched with chronologies from low-elevation sites, especially a Douglas-fir chronology from Vancouver Island, Canada, to show that the Electron trees died in 1507 CE. Latewood in the final ring was beginning to form, indicating the mudflow likely occurred in the late-summer months. What caused the Electron Mudflow is unknown, but this precise date will help to assess possible relationships with other events, assist in interpreting Indigenous narratives about the mudflow, and increase awareness of potential lahar hazards.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"133 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704185","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}
Anne-Sofie C. Ahm, Philip Fralick, John A. Higgins
Earth’s long-term climate is closely tied to the formation of carbonate sediments in the ocean, driving the ocean’s ability to moderate atmospheric CO2 levels. It has been hypothesized that in the Precambrian, this process was controlled by a “hidden” deep-sea carbonate sink. However, our results indicate that shallow-marine platforms have been the dominant mode of carbonate formation since the Mesoarchean. This conclusion is based on Ca isotopes from 2.8 Ga carbonates, which constrain the Ca isotope value of Mesoarchean seawater to −0.5‰ relative to modern values, strikingly similar to pre-Mesozoic values and suggesting that carbonate deposition mainly was confined to shallow-water platforms until the evolution of pelagic calcifiers in the Mesozoic.
{"title":"As it ever was: Calcium isotope constraints on Mesoarchean seawater chemistry","authors":"Anne-Sofie C. Ahm, Philip Fralick, John A. Higgins","doi":"10.1130/g53945.1","DOIUrl":"https://doi.org/10.1130/g53945.1","url":null,"abstract":"Earth’s long-term climate is closely tied to the formation of carbonate sediments in the ocean, driving the ocean’s ability to moderate atmospheric CO2 levels. It has been hypothesized that in the Precambrian, this process was controlled by a “hidden” deep-sea carbonate sink. However, our results indicate that shallow-marine platforms have been the dominant mode of carbonate formation since the Mesoarchean. This conclusion is based on Ca isotopes from 2.8 Ga carbonates, which constrain the Ca isotope value of Mesoarchean seawater to −0.5‰ relative to modern values, strikingly similar to pre-Mesozoic values and suggesting that carbonate deposition mainly was confined to shallow-water platforms until the evolution of pelagic calcifiers in the Mesozoic.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"79 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704184","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：