Comprehensive studies of martian volcanic landforms offer otherwise inaccessible insights into subsurface magmatic systems that evolve and differentiate over time. Through orbital spectral analyses of a long-lived volcanic system south of Pavonis Mons that, over multiple eruptions, transitioned from a fissure vent to a point-source cone-forming vent, we identified mineralogical changes across morphologically distinct units. The fissure-fed lava flows exhibit olivine spectral characteristics, indicating deep-sourced magma, likely from the mantle or lower crust, while younger, finger-shaped lava flows on the cone are dominated by high-calcium pyroxenes, indicating a more evolved magma source. While these two different-aged units originate from the same regional plumbing system, their mineralogical differences suggest magmatic differentiation through crustal storage, possible assimilation, and fractional crystallization during subsequent cooling. These findings enhance our understanding of magma evolution in the late Amazonian on Mars.
{"title":"Spectral evidence for magmatic differentiation within a martian plumbing system","authors":"Bartosz Pieterek, Valerie Payré, Thomas J. Jones","doi":"10.1130/g53969.1","DOIUrl":"https://doi.org/10.1130/g53969.1","url":null,"abstract":"Comprehensive studies of martian volcanic landforms offer otherwise inaccessible insights into subsurface magmatic systems that evolve and differentiate over time. Through orbital spectral analyses of a long-lived volcanic system south of Pavonis Mons that, over multiple eruptions, transitioned from a fissure vent to a point-source cone-forming vent, we identified mineralogical changes across morphologically distinct units. The fissure-fed lava flows exhibit olivine spectral characteristics, indicating deep-sourced magma, likely from the mantle or lower crust, while younger, finger-shaped lava flows on the cone are dominated by high-calcium pyroxenes, indicating a more evolved magma source. While these two different-aged units originate from the same regional plumbing system, their mineralogical differences suggest magmatic differentiation through crustal storage, possible assimilation, and fractional crystallization during subsequent cooling. These findings enhance our understanding of magma evolution in the late Amazonian on Mars.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"29 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089740","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}
Guihong Zhang, Yuntao Tian, Andrew V. Zuza, Junyi Li, Zengjie Zhang, Peizhen Zhang
Upwelling mantle plumes are recognized to modify the continental lithosphere by building craton-like keels or inducing thermal erosion−related thinning. Such plume-related modification may exert long-term control over subsequent deformation and topographic evolution. In the southeastern Tibetan Plateau (SETP), the late Permian Emeishan large igneous province (ELIP), generated by mantle plume activity, significantly modified the lithospheric architecture in this region. However, current geodynamic models of Cenozoic plateau formation largely neglect the impact of ELIP-related lithospheric modification. Here, we investigated spatial variations in Cenozoic deformation and exhumation across the ELIP’s inner and intermediate zones. These zones span from the plume head to its periphery and are cut by two major Cenozoic faults: the Ailaoshan−Red River (ALS-RR) and Xianshuihe (XSH) faults. Our results reveal minimal post-Oligocene exhumation within the inner zone (0.05−0.15 km/m.y.), in contrast to higher rates in the intermediate zone (0.2−0.3 km/m.y.) and along the ALS-RR (0.4−2.5 km/m.y.) and XSH faults (0.4−0.9 km/m.y.). The limited exhumation corresponds to weak deformation within the inner zone. Integrating geological and geophysical data, we suggest that the late Permian plume activity emplaced voluminous mantle-derived mafic-ultramafic intrusions into the crust beneath the ELIP’s inner zone, increasing crustal rigidity and resistance to Cenozoic deformation and exhumation. Our findings highlight how plume-related lithospheric modification may exert a lasting influence on intraplate deformation, persisting hundreds of millions of years after plume cessation.
{"title":"Plume-strengthened crust controlled post-Oligocene deformation partitioning in the southeastern Tibetan Plateau","authors":"Guihong Zhang, Yuntao Tian, Andrew V. Zuza, Junyi Li, Zengjie Zhang, Peizhen Zhang","doi":"10.1130/g53641.1","DOIUrl":"https://doi.org/10.1130/g53641.1","url":null,"abstract":"Upwelling mantle plumes are recognized to modify the continental lithosphere by building craton-like keels or inducing thermal erosion−related thinning. Such plume-related modification may exert long-term control over subsequent deformation and topographic evolution. In the southeastern Tibetan Plateau (SETP), the late Permian Emeishan large igneous province (ELIP), generated by mantle plume activity, significantly modified the lithospheric architecture in this region. However, current geodynamic models of Cenozoic plateau formation largely neglect the impact of ELIP-related lithospheric modification. Here, we investigated spatial variations in Cenozoic deformation and exhumation across the ELIP’s inner and intermediate zones. These zones span from the plume head to its periphery and are cut by two major Cenozoic faults: the Ailaoshan−Red River (ALS-RR) and Xianshuihe (XSH) faults. Our results reveal minimal post-Oligocene exhumation within the inner zone (0.05−0.15 km/m.y.), in contrast to higher rates in the intermediate zone (0.2−0.3 km/m.y.) and along the ALS-RR (0.4−2.5 km/m.y.) and XSH faults (0.4−0.9 km/m.y.). The limited exhumation corresponds to weak deformation within the inner zone. Integrating geological and geophysical data, we suggest that the late Permian plume activity emplaced voluminous mantle-derived mafic-ultramafic intrusions into the crust beneath the ELIP’s inner zone, increasing crustal rigidity and resistance to Cenozoic deformation and exhumation. Our findings highlight how plume-related lithospheric modification may exert a lasting influence on intraplate deformation, persisting hundreds of millions of years after plume cessation.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"83 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089739","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}
D. McIlroy, S. Denyszyn, P. Olschewski, S. Rosse-Guillevic, H. Muirhead-Hunt, D. Pérez-Pinedo, C. McKean, G. Pasinetti, B. Rideout, M.P. Steele, L.R. Menon, J.M. Neville, N. Chida, R.S. Taylor
The Ediacaran biota has been informally divided into three ecostratigraphic units: the lowermost deep marine Avalon Assemblage, the overlying shallow-marine White Sea Assemblage, and the uppermost Nama Assemblage. While there are some shared taxa among all three, they have been considered relatively robust, informal, biostratigraphic entities. We document a rich new fossil site that includes most of the Avalon Assemblage biota from the EM Coombs Surface at Inner Meadow, Newfoundland, Canada, and date it to 550.78 ± 0.60 Ma, equivalent to the youngest White Sea Assemblage faunas. This demonstrates that the Avalon and White Sea assemblages are contemporaneous, that the differences between them are ecological, not stratigraphic, and that the Avalon Assemblage biotas were also affected by the 550 Ma Kotlin Crisis that has hitherto been considered to only affect the White Sea Assemblage. The impoverished post-extinction Nama Assemblage succeeds the Kotlin Crisis, which our data reveal to be more profound than previously known. The Kotlin Crisis is considered to be the first significant extinction event experienced by the Eumetazoa, ∼10 m.y. before the Cambrian radiation.
埃迪卡拉纪生物群被非正式地划分为三个生态地层单元：最底部的深海阿瓦隆组合、上覆浅海白海组合和最上面的纳玛组合。虽然这三者之间有一些共同的分类群，但它们被认为是相对健全的、非正式的、生物地层学的实体。我们在加拿大纽芬兰的Inner Meadow的EM Coombs表面记录了一个丰富的新化石遗址，其中包括大部分Avalon组合生物群，并将其定年为550.78±0.60 Ma，相当于最年轻的白海组合动物群。这表明阿瓦隆组合和白海组合是同时期的，它们之间的差异是生态的，而不是地层的，并且阿瓦隆组合的生物群也受到550 Ma Kotlin危机的影响，迄今为止人们认为这种危机只影响白海组合。灭绝后贫穷的纳玛组合继承了科特林危机，我们的数据显示，它比以前所知的更为深刻。Kotlin危机被认为是真生动物经历的第一次重大灭绝事件，发生在寒武纪辐射之前约10万年。
{"title":"Ediacaran endlings from the Avalon Assemblage and the severity of the Kotlin Crisis: First documentation of the Inner Meadow Lagerstätte, Newfoundland, Canada","authors":"D. McIlroy, S. Denyszyn, P. Olschewski, S. Rosse-Guillevic, H. Muirhead-Hunt, D. Pérez-Pinedo, C. McKean, G. Pasinetti, B. Rideout, M.P. Steele, L.R. Menon, J.M. Neville, N. Chida, R.S. Taylor","doi":"10.1130/g54217.1","DOIUrl":"https://doi.org/10.1130/g54217.1","url":null,"abstract":"The Ediacaran biota has been informally divided into three ecostratigraphic units: the lowermost deep marine Avalon Assemblage, the overlying shallow-marine White Sea Assemblage, and the uppermost Nama Assemblage. While there are some shared taxa among all three, they have been considered relatively robust, informal, biostratigraphic entities. We document a rich new fossil site that includes most of the Avalon Assemblage biota from the EM Coombs Surface at Inner Meadow, Newfoundland, Canada, and date it to 550.78 ± 0.60 Ma, equivalent to the youngest White Sea Assemblage faunas. This demonstrates that the Avalon and White Sea assemblages are contemporaneous, that the differences between them are ecological, not stratigraphic, and that the Avalon Assemblage biotas were also affected by the 550 Ma Kotlin Crisis that has hitherto been considered to only affect the White Sea Assemblage. The impoverished post-extinction Nama Assemblage succeeds the Kotlin Crisis, which our data reveal to be more profound than previously known. The Kotlin Crisis is considered to be the first significant extinction event experienced by the Eumetazoa, ∼10 m.y. before the Cambrian radiation.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"93 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089807","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}
We explore the fate of subducted continental margins using thermomechanical modeling with constant-force boundary conditions. Under certain conditions, large volumes of upper crust can get subducted to mantle depth, detach from the slab, and rise through the upper plate’s lithosphere even against considerable compressive tectonic stress. At the surface, such an event is expressed as a phase of intense horizontal extension and magmatism internal of the oceanic suture zone. The process can create normal-fault-bounded core complexes hundreds of kilometers wide, in which metamorphic continental crust derived from the subducting plate is exposed. Horizontal tectonic stress and the thickness of the downgoing upper crust control the width of complexes, their topographic elevation, and the subduction depth of exposed rocks. We propose that the Rhodope Metamorphic Complex on the Balkan Peninsula represents a prime example for such vertical extrusion internal of a suture zone. Lower tectonic units in this domain exhibit Eocene high-pressure metamorphism and nappe stacking followed by massive magmatism and large-offset normal faulting. Despite more than 100 km of extension in Cenozoic times, the area still has thick crust. Our modeling results support schemes that attribute the lower units of the Rhodope Metamorphic Complex to the subducted Adriatic plate.
{"title":"The Rhodope Metamorphic Complex as a case for extreme vertical extrusion","authors":"Iskander A. Muldashev, Thorsten J. Nagel","doi":"10.1130/g53889.1","DOIUrl":"https://doi.org/10.1130/g53889.1","url":null,"abstract":"We explore the fate of subducted continental margins using thermomechanical modeling with constant-force boundary conditions. Under certain conditions, large volumes of upper crust can get subducted to mantle depth, detach from the slab, and rise through the upper plate’s lithosphere even against considerable compressive tectonic stress. At the surface, such an event is expressed as a phase of intense horizontal extension and magmatism internal of the oceanic suture zone. The process can create normal-fault-bounded core complexes hundreds of kilometers wide, in which metamorphic continental crust derived from the subducting plate is exposed. Horizontal tectonic stress and the thickness of the downgoing upper crust control the width of complexes, their topographic elevation, and the subduction depth of exposed rocks. We propose that the Rhodope Metamorphic Complex on the Balkan Peninsula represents a prime example for such vertical extrusion internal of a suture zone. Lower tectonic units in this domain exhibit Eocene high-pressure metamorphism and nappe stacking followed by massive magmatism and large-offset normal faulting. Despite more than 100 km of extension in Cenozoic times, the area still has thick crust. Our modeling results support schemes that attribute the lower units of the Rhodope Metamorphic Complex to the subducted Adriatic plate.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"8 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089742","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}
Back-arc basin basalts are broadly similar in composition to mid-ocean ridge basalts, but also incorporate arc-like geochemical signatures. The processes governing melt transport from the arc to the back-arc spreading center remain enigmatic, particularly beneath slow-spreading systems with limited melt volumes, where imaging of small-scale structures has been challenging. Here, we use multimode Rayleigh-wave tomography, enhanced by increased raypath coverage through both two- and three-station interferometry, to resolve S-wave velocity structure down to ∼100 km depth beneath the central Mariana subduction zone. Our model reveals a triangle-like low-velocity anomaly at 15−30 km depth beneath the Mariana trough and an elliptical low-velocity anomaly at 50−90 km depth beneath the Mariana arc, both consistent with melt equilibration depths from thermobarometry. Additionally, a cylindrical low-velocity anomaly extends from the base of the triangle-like low-velocity anomaly to ∼80 km depth and appears weakly connected to the anomaly beneath the arc. We interpret this feature as diapiric upwelling that links melt sources beneath the arc and back-arc.
{"title":"Melt production and transport beneath the slow-spreading Mariana arc−back-arc system","authors":"Tae-shin Kim, Sung-Joon Chang","doi":"10.1130/g53706.1","DOIUrl":"https://doi.org/10.1130/g53706.1","url":null,"abstract":"Back-arc basin basalts are broadly similar in composition to mid-ocean ridge basalts, but also incorporate arc-like geochemical signatures. The processes governing melt transport from the arc to the back-arc spreading center remain enigmatic, particularly beneath slow-spreading systems with limited melt volumes, where imaging of small-scale structures has been challenging. Here, we use multimode Rayleigh-wave tomography, enhanced by increased raypath coverage through both two- and three-station interferometry, to resolve S-wave velocity structure down to ∼100 km depth beneath the central Mariana subduction zone. Our model reveals a triangle-like low-velocity anomaly at 15−30 km depth beneath the Mariana trough and an elliptical low-velocity anomaly at 50−90 km depth beneath the Mariana arc, both consistent with melt equilibration depths from thermobarometry. Additionally, a cylindrical low-velocity anomaly extends from the base of the triangle-like low-velocity anomaly to ∼80 km depth and appears weakly connected to the anomaly beneath the arc. We interpret this feature as diapiric upwelling that links melt sources beneath the arc and back-arc.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"79 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089741","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}
Distributed volcanic fields occur globally, but the processes that control volcanic composition and behavior remain uncertain. To investigate the controls on eruptive style, melt storage, and hazards in a system with voluminous mafic and intermediate and/or silicic lavas, we seismically imaged the subsurface beneath the San Francisco volcanic field in northern Arizona (USA). Results reveal two partial melt zones and regional changes in crustal thickness, related to lower crustal removal. San Francisco Mountain, a felsic stratovolcano, is located atop a boundary between intact and removed crust. This lateral boundary in lithospheric properties concentrates melt into mid- and lower-crustal reservoirs, enabling felsic volcanism in this dominantly basaltic field. This demonstrates how lateral lithospheric gradients focus melt in distributed volcanic fields, with removal playing a key role in creating these gradients.
{"title":"Tectonic controls on magma storage beneath a distributed volcanic field","authors":"Ryan Porter, Eric Kiser, Mary R. Reid","doi":"10.1130/g54058.1","DOIUrl":"https://doi.org/10.1130/g54058.1","url":null,"abstract":"Distributed volcanic fields occur globally, but the processes that control volcanic composition and behavior remain uncertain. To investigate the controls on eruptive style, melt storage, and hazards in a system with voluminous mafic and intermediate and/or silicic lavas, we seismically imaged the subsurface beneath the San Francisco volcanic field in northern Arizona (USA). Results reveal two partial melt zones and regional changes in crustal thickness, related to lower crustal removal. San Francisco Mountain, a felsic stratovolcano, is located atop a boundary between intact and removed crust. This lateral boundary in lithospheric properties concentrates melt into mid- and lower-crustal reservoirs, enabling felsic volcanism in this dominantly basaltic field. This demonstrates how lateral lithospheric gradients focus melt in distributed volcanic fields, with removal playing a key role in creating these gradients.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"79 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089750","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}
Hadrien Henry, William D. Smith, Mathieu Rospabé, Anastassia Borisova, Georges Ceuleneer
Silicate inclusions in chromite crystals often occur at high population densities and sometimes even share a common shape preferred orientation. These inclusions are arranged in a two-dimensional grid, herein referred to as “waffle-iron patterns” (WIPs). WIPs have been observed in the different geological contexts where chromite crystals nucleate. Their ubiquity and exotic mineralogy raise questions about their origin. Crystallographic data acquired on WIP-bearing chromite crystals demonstrate a systematic host:inclusion crystallographic orientation relationship. It is shown that WIPs result from syngrowth epitaxial nucleation of silicates onto initially skeletal chromite crystals; thus, they are markers of cryptic and transient out-of-equilibrium magmatic systems. The implication is that chromite-hosted silicate inclusions may not be reliable proxies for the early stages of magmatic systems.
{"title":"Out-of-equilibrium growth recorded by mineral inclusions with implications for their suitability as melt proxies: Evidence from chromite","authors":"Hadrien Henry, William D. Smith, Mathieu Rospabé, Anastassia Borisova, Georges Ceuleneer","doi":"10.1130/g54021.1","DOIUrl":"https://doi.org/10.1130/g54021.1","url":null,"abstract":"Silicate inclusions in chromite crystals often occur at high population densities and sometimes even share a common shape preferred orientation. These inclusions are arranged in a two-dimensional grid, herein referred to as “waffle-iron patterns” (WIPs). WIPs have been observed in the different geological contexts where chromite crystals nucleate. Their ubiquity and exotic mineralogy raise questions about their origin. Crystallographic data acquired on WIP-bearing chromite crystals demonstrate a systematic host:inclusion crystallographic orientation relationship. It is shown that WIPs result from syngrowth epitaxial nucleation of silicates onto initially skeletal chromite crystals; thus, they are markers of cryptic and transient out-of-equilibrium magmatic systems. The implication is that chromite-hosted silicate inclusions may not be reliable proxies for the early stages of magmatic systems.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"216 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033647","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}
The thermal structure of the lithosphere influences both the extensional and contractional phases of rift-inversion orogenesis. During the Proterozoic, elevated geotherms likely favored wide rift formation, yet examples of wide rift-inversion orogens are absent from the literature. Using 2-D thermo-mechanical models, we show that narrow rifts formed under colder initial geotherms invert into localized orogenic wedges flanked by foreland basins, largely utilizing rift architecture. Wide rifts formed under warmer initial geotherms, representing Proterozoic conditions, invert into broad, low-relief orogenic plateaus through distributed upper crustal faulting and ductile flow in the underlying lithosphere. Importantly, postrift tectonic quiescence modestly affects narrow rift inversion, primarily widening the orogenic wedge, but fundamentally alters wide rift inversion by promoting lithospheric cooling, embrittlement, and the development of deep contractional shear zones offsetting the Moho by 10−20 km. This wide rift-inversion framework may provide an explanation for distributed shortening and low topographic relief in Proterozoic orogens.
{"title":"From wide rifts to orogens: A new perspective for Proterozoic tectonics","authors":"Youseph Ibrahim, Patrice F. Rey","doi":"10.1130/g54232.1","DOIUrl":"https://doi.org/10.1130/g54232.1","url":null,"abstract":"The thermal structure of the lithosphere influences both the extensional and contractional phases of rift-inversion orogenesis. During the Proterozoic, elevated geotherms likely favored wide rift formation, yet examples of wide rift-inversion orogens are absent from the literature. Using 2-D thermo-mechanical models, we show that narrow rifts formed under colder initial geotherms invert into localized orogenic wedges flanked by foreland basins, largely utilizing rift architecture. Wide rifts formed under warmer initial geotherms, representing Proterozoic conditions, invert into broad, low-relief orogenic plateaus through distributed upper crustal faulting and ductile flow in the underlying lithosphere. Importantly, postrift tectonic quiescence modestly affects narrow rift inversion, primarily widening the orogenic wedge, but fundamentally alters wide rift inversion by promoting lithospheric cooling, embrittlement, and the development of deep contractional shear zones offsetting the Moho by 10−20 km. This wide rift-inversion framework may provide an explanation for distributed shortening and low topographic relief in Proterozoic orogens.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"18 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033648","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}
Stephen E. Grasby, I. Rod Smith, Wanju Yuan, Andriy Sheremet
The Smoking Hills (Ingniryuat) is a polar desert of Arctic Canada that contains naturally occurring streams and ponds of hyperacidic (pH <−2) metal-rich brines (total dissolved solids up to 394,000 mg/L). Acid waters are formed though oxidation of pyrite and metal-rich mudstones of the Late Cretaceous Smoking Hills Formation. Water in contact with the mudstones rapidly changes chemistry, becoming acidic, metal-rich, and opaque orange due to precipitation of Fe-sulfates. Acid generation occurs through fluvial incision through bedrock strata and mass wasting of Smoking Hills Formation mudstones due to coastal erosion, stream undercutting, permafrost thaw, and ground-ice melt. These hyperacidic metal-rich waters discharge to larger river systems and are transported to the Arctic Ocean with uncertain impact. We suggest that climate warming may increase slumping and associated debris flows, impound more surface ponds and stream courses, generate more acid waters, amplify toxic-metal flux to the environment, and drive river “rusting.”
{"title":"Release of toxic-metal acid brines related to slumping of Cretaceous mudstones—Smoking Hills (Ingniryuat), Arctic Canada","authors":"Stephen E. Grasby, I. Rod Smith, Wanju Yuan, Andriy Sheremet","doi":"10.1130/g53747.1","DOIUrl":"https://doi.org/10.1130/g53747.1","url":null,"abstract":"The Smoking Hills (Ingniryuat) is a polar desert of Arctic Canada that contains naturally occurring streams and ponds of hyperacidic (pH &lt;−2) metal-rich brines (total dissolved solids up to 394,000 mg/L). Acid waters are formed though oxidation of pyrite and metal-rich mudstones of the Late Cretaceous Smoking Hills Formation. Water in contact with the mudstones rapidly changes chemistry, becoming acidic, metal-rich, and opaque orange due to precipitation of Fe-sulfates. Acid generation occurs through fluvial incision through bedrock strata and mass wasting of Smoking Hills Formation mudstones due to coastal erosion, stream undercutting, permafrost thaw, and ground-ice melt. These hyperacidic metal-rich waters discharge to larger river systems and are transported to the Arctic Ocean with uncertain impact. We suggest that climate warming may increase slumping and associated debris flows, impound more surface ponds and stream courses, generate more acid waters, amplify toxic-metal flux to the environment, and drive river “rusting.”","PeriodicalId":12642,"journal":{"name":"Geology","volume":"18 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033650","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}
Jian-Jun Fan, Si-Lin Sun, Jian-Bo Zhou, Simon A. Wilde, Yang Wang, Jun-Pu Lv
The trigger for frequent extinctions during the Phanerozoic remains a persistent and unresolved frontier issue in Earth sciences. We present a detailed analysis of oceanic island, seamount, and plateau remnants in the Tibetan Plateau that trace the evolution of the Meso- and Neo-Tethys oceans, incorporating new and published data. During the Triassic, three major episodes of marine large igneous provinces (LIPs) formed at 250−248 Ma, 233−231 Ma, and 210−208 Ma. By integrating geological records of these LIP episodes with Triassic geological data sets, we demonstrate a correlation between marine LIPs and at least four extinctions in marine biota, driven by the resultant anoxic-euxinic events. Consequently, marine LIPs emerge as a primary driver of recurrent mass extinctions. Numerous previously unexplained extinctions throughout Earth’s history may potentially result from currently unidentified components of marine LIPs occurring as fragments within orogenic belts.
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