Lining Cheng, Jianye Chen, Yongsheng Zhou, Christopher J. Spiers
A prominent set of N-S−trending normal faults hosts most of the destructive earthquakes in the central Tibetan Plateau, including the 2025 Mw 7.1 Dingri earthquake. The source physics of these earthquakes is unclear. However, fault mirrors provide important records of fault slip. We found a special type of fault mirror, tourmaline fault mirrors (TFMs), to be remarkably widespread in the N-S normal fault systems of the Himalayan orogen, these being intermittently yet repeatedly exposed for tens of kilometers along strike, suggesting that the TFMs likely hosted large earthquakes. Here, we report the first field- to nanoscale study of these TFMs from the Mount Everest area. Microstructural analyses show that a typical TFM consists of three distinct layers, from the slip surface to the gneiss host rock: a 30−80-nm-thick film of amorphous tourmaline, a net-textured layer (20−100 µm) containing tourmaline clasts in an amorphous tourmaline matrix, and a dynamically recrystallized layer of tourmaline grains (≤400 µm). The observed amorphous material, micropores, and embayed residual tourmaline grains, combined with Ti-in-quartz thermometry implying temperatures >840 °C at the slip surface, suggest that the TFMs formed by frictional melting during seismic slip on tourmaline-filled veins. Combining unstable frictional slip data for tourmaline gouge at 200−300 °C with the coexistence of tourmaline cataclasites and TFMs, we propose that tourmaline veins play a key role in controlling seismic rupture on the N-S normal fault systems of the Himalayan orogen.
{"title":"Tourmaline fault mirrors record seismic slip on N-S normal faults in the Himalayan orogen","authors":"Lining Cheng, Jianye Chen, Yongsheng Zhou, Christopher J. Spiers","doi":"10.1130/g54248.1","DOIUrl":"https://doi.org/10.1130/g54248.1","url":null,"abstract":"A prominent set of N-S−trending normal faults hosts most of the destructive earthquakes in the central Tibetan Plateau, including the 2025 Mw 7.1 Dingri earthquake. The source physics of these earthquakes is unclear. However, fault mirrors provide important records of fault slip. We found a special type of fault mirror, tourmaline fault mirrors (TFMs), to be remarkably widespread in the N-S normal fault systems of the Himalayan orogen, these being intermittently yet repeatedly exposed for tens of kilometers along strike, suggesting that the TFMs likely hosted large earthquakes. Here, we report the first field- to nanoscale study of these TFMs from the Mount Everest area. Microstructural analyses show that a typical TFM consists of three distinct layers, from the slip surface to the gneiss host rock: a 30−80-nm-thick film of amorphous tourmaline, a net-textured layer (20−100 µm) containing tourmaline clasts in an amorphous tourmaline matrix, and a dynamically recrystallized layer of tourmaline grains (≤400 µm). The observed amorphous material, micropores, and embayed residual tourmaline grains, combined with Ti-in-quartz thermometry implying temperatures >840 °C at the slip surface, suggest that the TFMs formed by frictional melting during seismic slip on tourmaline-filled veins. Combining unstable frictional slip data for tourmaline gouge at 200−300 °C with the coexistence of tourmaline cataclasites and TFMs, we propose that tourmaline veins play a key role in controlling seismic rupture on the N-S normal fault systems of the Himalayan orogen.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"36 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147371517","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}
Marine gas hydrates represent a huge hydrocarbon reservoir in deep-water continental margins and a potential major source of positive feedback to a warming climate. Using three-dimensional seismic reflection data from the West African hydrate province offshore Namibia, we document seismic amplitude anomalies, 10−32 milliseconds (ms) high and 50−370 m wide, within the gas hydrate stability zone (GHSZ), with up to 33 ms velocity pull-up affecting reflections many hundreds of ms vertically below the anomalies; and circular depressions, 139−559 m in diameter, below the GHSZ. We interpret the anomalies as subsurface gas hydrate “plugs,” consisting of millions of cubic meters of massive hydrate accumulations within the GHSZ, and the craters beneath the GHSZ as associated dissociation-collapse structures. This discovery reveals a new type and dynamics of massive methane hydrate formation along continental margins and requires a reevaluation of previous interpretations of columnar seismic image distortions as kilometer-long fluid flow features.
{"title":"Subsurface gas hydrate plugs","authors":"Benedict L. Campbell, Mads Huuse","doi":"10.1130/g54292.1","DOIUrl":"https://doi.org/10.1130/g54292.1","url":null,"abstract":"Marine gas hydrates represent a huge hydrocarbon reservoir in deep-water continental margins and a potential major source of positive feedback to a warming climate. Using three-dimensional seismic reflection data from the West African hydrate province offshore Namibia, we document seismic amplitude anomalies, 10−32 milliseconds (ms) high and 50−370 m wide, within the gas hydrate stability zone (GHSZ), with up to 33 ms velocity pull-up affecting reflections many hundreds of ms vertically below the anomalies; and circular depressions, 139−559 m in diameter, below the GHSZ. We interpret the anomalies as subsurface gas hydrate “plugs,” consisting of millions of cubic meters of massive hydrate accumulations within the GHSZ, and the craters beneath the GHSZ as associated dissociation-collapse structures. This discovery reveals a new type and dynamics of massive methane hydrate formation along continental margins and requires a reevaluation of previous interpretations of columnar seismic image distortions as kilometer-long fluid flow features.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"32 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147371237","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}
Stefano Tenuta, Katy A. Evans, Steven M. Reddy, David W. Saxey, Denis Fougerouse, Brian Tattitch
Reducing conditions are typical of incipient serpentinization in which sulfides and alloys break down to form secondary phases. Sulfides and alloys are the main hosts of platinum group elements (PGEs) in serpentinites, and the role of serpentinization in the remobilization of these elements is controversial. Here, we replicated early serpentinization using cold-seal pressure vessels, reacting a mixture of olivine, synthetic laurite, and water at 50 MPa and temperatures of 250−350 °C for durations of 1−4 d. Olivine reacts partially to form serpentine and brucite. Laurite breaks down to form RuSx with variable Ru:S ratios plus euhedral FeS grains. There are no systematic relationships among temperature, time, water content, and the composition of the Ru phase. No neoformed Ru phases were identified, consistent with limited Ru mobility during serpentinization. Silicate mineral assemblages and breakdown of primary laurite are consistent with observations in natural and experimental systems where incipient serpentinization occurred at highly reducing conditions. The results are consistent with decoupling of Ir group PGEs and Pd group PGEs during serpentinization and suggest that serpentinization may affect PGEs differently in different geodynamic settings, with consequences for global PGE cycling.
{"title":"Role of serpentinization in platinum group element (PGE) mobilization—Evidence from experiments","authors":"Stefano Tenuta, Katy A. Evans, Steven M. Reddy, David W. Saxey, Denis Fougerouse, Brian Tattitch","doi":"10.1130/g53970.1","DOIUrl":"https://doi.org/10.1130/g53970.1","url":null,"abstract":"Reducing conditions are typical of incipient serpentinization in which sulfides and alloys break down to form secondary phases. Sulfides and alloys are the main hosts of platinum group elements (PGEs) in serpentinites, and the role of serpentinization in the remobilization of these elements is controversial. Here, we replicated early serpentinization using cold-seal pressure vessels, reacting a mixture of olivine, synthetic laurite, and water at 50 MPa and temperatures of 250−350 °C for durations of 1−4 d. Olivine reacts partially to form serpentine and brucite. Laurite breaks down to form RuSx with variable Ru:S ratios plus euhedral FeS grains. There are no systematic relationships among temperature, time, water content, and the composition of the Ru phase. No neoformed Ru phases were identified, consistent with limited Ru mobility during serpentinization. Silicate mineral assemblages and breakdown of primary laurite are consistent with observations in natural and experimental systems where incipient serpentinization occurred at highly reducing conditions. The results are consistent with decoupling of Ir group PGEs and Pd group PGEs during serpentinization and suggest that serpentinization may affect PGEs differently in different geodynamic settings, with consequences for global PGE cycling.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"4 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147371238","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}
Tianran Zhang, C. Brenhin Keller, Jessica R. Creveling, Reina Harding, Lyle L. Nelson, Emily F. Smith, Justin V. Strauss
Geological data and basin subsidence modeling results from the western margin of North America (Laurentia) have supported a late Ediacaran to early Cambrian age for the onset of passive margin sedimentation following the protracted breakup of Rodinia. However, several recent studies posit that increased early Cambrian subsidence may instead be driven primarily by eustatic sea-level rise. Here, we present new quantitative subsidence analyses of Neoproterozoic−Paleozoic strata in the southern Great Basin, USA, using decompaction, backstripping, and Bayesian thermal subsidence modeling methods that statistically propagate uncertainties. Our results support polyphase extension along the ancestral western margin of Laurentia and are consistent with a rift-drift transition in southwestern Laurentia that broadly overlaps with the Ediacaran−Cambrian transition. Although we do not discount the role of eustasy in facilitating increased accommodation space in the early Cambrian, the magnitude and local variability of this signal require additional tectonic forcings.
{"title":"Bayesian tectonic subsidence modeling supports polyphase extension of the western continental margin of Laurentia","authors":"Tianran Zhang, C. Brenhin Keller, Jessica R. Creveling, Reina Harding, Lyle L. Nelson, Emily F. Smith, Justin V. Strauss","doi":"10.1130/g54081.1","DOIUrl":"https://doi.org/10.1130/g54081.1","url":null,"abstract":"Geological data and basin subsidence modeling results from the western margin of North America (Laurentia) have supported a late Ediacaran to early Cambrian age for the onset of passive margin sedimentation following the protracted breakup of Rodinia. However, several recent studies posit that increased early Cambrian subsidence may instead be driven primarily by eustatic sea-level rise. Here, we present new quantitative subsidence analyses of Neoproterozoic−Paleozoic strata in the southern Great Basin, USA, using decompaction, backstripping, and Bayesian thermal subsidence modeling methods that statistically propagate uncertainties. Our results support polyphase extension along the ancestral western margin of Laurentia and are consistent with a rift-drift transition in southwestern Laurentia that broadly overlaps with the Ediacaran−Cambrian transition. Although we do not discount the role of eustasy in facilitating increased accommodation space in the early Cambrian, the magnitude and local variability of this signal require additional tectonic forcings.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"26 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147371239","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 tempo of Earth’s tectonic engine is recorded in the timing of mineral systems, offering a means to trace the evolving rhythm of supercontinent cycles through deep time. Using spectral and wavelet analyses of volcanic-hosted massive sulfide (VHMS), orogenic gold, and pegmatite deposit ages, I identify periodic signals linked to supercontinent-scale processes. Spectral and wavelet analyses reveal a prominent ∼0.75 Gyr band in VHMS and pegmatite systems, consistent with long-wavelength tectonic forcing. Pegmatites, in particular, show recurring age peaks broadly synchronous with late stages of supercontinent tenure and an apparent shift in dominant periodicity from ∼1 Gyr in the Archean−Paleoproterozoic toward shorter (∼0.6−0.7 Gyr) intervals by the Neoproterozoic. Together, these observations indicate that secular mantle cooling drove progressively faster cycles of continental assembly and dispersal as modern-style plate behavior became established.
{"title":"Pacing supercontinent rhythms from the metallogenic record","authors":"C.L. Kirkland","doi":"10.1130/g54471.1","DOIUrl":"https://doi.org/10.1130/g54471.1","url":null,"abstract":"The tempo of Earth’s tectonic engine is recorded in the timing of mineral systems, offering a means to trace the evolving rhythm of supercontinent cycles through deep time. Using spectral and wavelet analyses of volcanic-hosted massive sulfide (VHMS), orogenic gold, and pegmatite deposit ages, I identify periodic signals linked to supercontinent-scale processes. Spectral and wavelet analyses reveal a prominent ∼0.75 Gyr band in VHMS and pegmatite systems, consistent with long-wavelength tectonic forcing. Pegmatites, in particular, show recurring age peaks broadly synchronous with late stages of supercontinent tenure and an apparent shift in dominant periodicity from ∼1 Gyr in the Archean−Paleoproterozoic toward shorter (∼0.6−0.7 Gyr) intervals by the Neoproterozoic. Together, these observations indicate that secular mantle cooling drove progressively faster cycles of continental assembly and dispersal as modern-style plate behavior became established.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"11 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147371241","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}
Interactions between orogenic plateau growth and environmental change, which play a key role in shaping Earth, are most pronounced in the Tibetan Plateau, affording the opportunity to explore how tectonics is coupled to surface processes during plateau uplift. The Linzhou and Wuyu depocenters of the regional intermontane basin in the Gangdese arc record a similar paleodrainage and surface evolution at ca. 60−48 Ma and 31−0 Ma, respectively, as detected by detrital zircon and apatite provenance analysis. A switch in detrital zircon and apatite populations from old and complex (polycyclic) to predominantly post−70 Ma sources in both sections highlights a decrease in sediment supply from external sources, likely caused by high-relief topography arising from surface uplift blocking distal headwaters. Abundant syndepositional zircon and apatite document rapid exhumation at ca. 54−51 Ma and 15−8 Ma, respectively, followed by a return to old (pre−70 Ma) sources with polycyclic zircon implying reactivated distal headwaters due to subsidence. The similar surface uplift and subsidence histories of the two locations in the Gangdese arc basin can be best explained by detachment of the Neo-Tethyan oceanic slab and Indian continental lithosphere, respectively, consistent with crustal thinning documented by Eu anomalies in detrital zircon. Lithospheric foundering led to asthenospheric upwelling and removed downward slab pull beneath Lhasa, triggering magmatism and uplift followed by surface subsidence linked to ongoing underthrusting. Consequently, two similar episodes of paleoelevation variations resulted from these two phases of lithospheric detachment.
{"title":"The surface response to two episodes of lithosphere underthrusting and detachment during Tibetan Plateau growth","authors":"Er-Kun Xue, Qiang Wang, David Chew, Wei-Wei Xue, Wang-Chao Li, Tong-Yu Huang","doi":"10.1130/g54475.1","DOIUrl":"https://doi.org/10.1130/g54475.1","url":null,"abstract":"Interactions between orogenic plateau growth and environmental change, which play a key role in shaping Earth, are most pronounced in the Tibetan Plateau, affording the opportunity to explore how tectonics is coupled to surface processes during plateau uplift. The Linzhou and Wuyu depocenters of the regional intermontane basin in the Gangdese arc record a similar paleodrainage and surface evolution at ca. 60−48 Ma and 31−0 Ma, respectively, as detected by detrital zircon and apatite provenance analysis. A switch in detrital zircon and apatite populations from old and complex (polycyclic) to predominantly post−70 Ma sources in both sections highlights a decrease in sediment supply from external sources, likely caused by high-relief topography arising from surface uplift blocking distal headwaters. Abundant syndepositional zircon and apatite document rapid exhumation at ca. 54−51 Ma and 15−8 Ma, respectively, followed by a return to old (pre−70 Ma) sources with polycyclic zircon implying reactivated distal headwaters due to subsidence. The similar surface uplift and subsidence histories of the two locations in the Gangdese arc basin can be best explained by detachment of the Neo-Tethyan oceanic slab and Indian continental lithosphere, respectively, consistent with crustal thinning documented by Eu anomalies in detrital zircon. Lithospheric foundering led to asthenospheric upwelling and removed downward slab pull beneath Lhasa, triggering magmatism and uplift followed by surface subsidence linked to ongoing underthrusting. Consequently, two similar episodes of paleoelevation variations resulted from these two phases of lithospheric detachment.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"6 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147371240","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}
Elizabeth J. Davis, Juliet G. Crider, Ralph A. Haugerud, Emily Roland, Ginevra Moore
Submerged marine terraces in Puget Sound, deformed across the Seattle fault zone (SFZ), indicate that only one earthquake as large as M ∼7.5 has occurred in at least the past 11 k.y. Previous paleoseismic studies documented an M ∼7.5 earthquake between 923 and 924 CE, which uplifted coastal marine terraces by as much as 8 m. We demonstrated that this earthquake was the only such event since ca. 11 ka by mapping and quantifying deformation of older marine terraces that are now submerged in Puget Sound. The submerged terraces, attributed to a late-glacial sea-level lowstand, record both glacial isostatic rebound and tectonic deformation. Vertical offset of the ca. 11 ka terraces within the SFZ is comparable to that of the marine terraces uplifted in 923 CE, implying no additional large (M >∼7.5) earthquake on the SFZ since ca. 11 ka. This result implies a longer recurrence interval than current hazard estimates, which assume recurrence of M >7.1 events every 5 k.y. Our mapping of SFZ deformation since ca. 11 ka also supports fault segmentation and contiguous block uplift between the Seattle and Tacoma fault zones.
{"title":"Deformed submarine terraces in Puget Sound, Pacific Northwest, indicate only one M >∼7.5 earthquake on the Seattle fault zone in the past 11,000 yr","authors":"Elizabeth J. Davis, Juliet G. Crider, Ralph A. Haugerud, Emily Roland, Ginevra Moore","doi":"10.1130/g53496.1","DOIUrl":"https://doi.org/10.1130/g53496.1","url":null,"abstract":"Submerged marine terraces in Puget Sound, deformed across the Seattle fault zone (SFZ), indicate that only one earthquake as large as M ∼7.5 has occurred in at least the past 11 k.y. Previous paleoseismic studies documented an M ∼7.5 earthquake between 923 and 924 CE, which uplifted coastal marine terraces by as much as 8 m. We demonstrated that this earthquake was the only such event since ca. 11 ka by mapping and quantifying deformation of older marine terraces that are now submerged in Puget Sound. The submerged terraces, attributed to a late-glacial sea-level lowstand, record both glacial isostatic rebound and tectonic deformation. Vertical offset of the ca. 11 ka terraces within the SFZ is comparable to that of the marine terraces uplifted in 923 CE, implying no additional large (M >∼7.5) earthquake on the SFZ since ca. 11 ka. This result implies a longer recurrence interval than current hazard estimates, which assume recurrence of M >7.1 events every 5 k.y. Our mapping of SFZ deformation since ca. 11 ka also supports fault segmentation and contiguous block uplift between the Seattle and Tacoma fault zones.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"11 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147319737","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}
Janina K. Gillies, Edward W. Llewellin, Fabian B. Wadsworth, Colin Rennie
Lauoho o Pele (often called Pele’s hair) is a common product of basaltic volcanism, produced during Hawaiian lava fountaining, gas jetting, and on the surface of flowing lava. The morphology—long thin strands of glass—indicates that these strands are formed through stretching of filaments of melt. The prevailing model is that they are formed by the action of jets of volcanic gas that “spin out” threads of melt, which quench as hairs. However, this mechanism does not explain the formation of lauoho o Pele on lava flows and lava lakes, or the occurrence of “hanks” of lauoho o Pele—bundles of hundreds to thousands of near-identical aligned strands. We propose and test an alternative mechanism: that lauoho o Pele can be formed by the extreme stretching of parcels of bubbly magma. We created pucks of synthetic bubbly magma using techniques derived from artistic hot-glass working, which we then stretched mechanically. This process produces bundles of filaments, similar to lauoho o Pele, via the stretching of the plateau borders where three bubbles meet; the number of filaments is determined by the abundance of bubbles in the molten glass. We find that lauoho o Pele forms at high vesicularity in our experiments, which is consistent with the interiors of high Hawaiian lava fountains, and the surfaces of lava lakes, and proximal and intubated lava flows.
Lauoho o Pele（通常被称为Pele的头发）是玄武岩火山作用的常见产物，在夏威夷熔岩喷吐、气体喷射和流动的熔岩表面产生。长而细的玻璃细丝的形态表明，这些细丝是由熔体细丝拉伸而形成的。流行的模型是，它们是由火山气体喷射的作用形成的，火山气体“旋转”出熔体，熔体像头发一样熄灭。然而，这一机制并不能解释熔岩流和熔岩湖上熔岩流的形成，也不能解释熔岩流和熔岩湖上熔岩流的形成，也不能解释数百到数千条几乎相同的排列成束的熔岩流的形成。我们提出并测试了另一种机制：贝利火山可以由气泡岩浆团的极端拉伸形成。我们使用源自艺术热玻璃工艺的技术制作了合成气泡岩浆，然后我们用机械拉伸。这个过程通过三个气泡相遇的高原边界的延伸，产生了类似于lauoho和Pele的细丝束；细丝的数量是由熔融玻璃中气泡的丰度决定的。我们在实验中发现lauoho o Pele形成于高泡度，这与夏威夷高泡熔岩喷泉内部、熔岩湖表面以及近端和插管熔岩流相一致。
{"title":"Formation of lauoho o Pele (Pele’s hair) by extreme stretching of bubbly magma","authors":"Janina K. Gillies, Edward W. Llewellin, Fabian B. Wadsworth, Colin Rennie","doi":"10.1130/g53972.1","DOIUrl":"https://doi.org/10.1130/g53972.1","url":null,"abstract":"Lauoho o Pele (often called Pele’s hair) is a common product of basaltic volcanism, produced during Hawaiian lava fountaining, gas jetting, and on the surface of flowing lava. The morphology—long thin strands of glass—indicates that these strands are formed through stretching of filaments of melt. The prevailing model is that they are formed by the action of jets of volcanic gas that “spin out” threads of melt, which quench as hairs. However, this mechanism does not explain the formation of lauoho o Pele on lava flows and lava lakes, or the occurrence of “hanks” of lauoho o Pele—bundles of hundreds to thousands of near-identical aligned strands. We propose and test an alternative mechanism: that lauoho o Pele can be formed by the extreme stretching of parcels of bubbly magma. We created pucks of synthetic bubbly magma using techniques derived from artistic hot-glass working, which we then stretched mechanically. This process produces bundles of filaments, similar to lauoho o Pele, via the stretching of the plateau borders where three bubbles meet; the number of filaments is determined by the abundance of bubbles in the molten glass. We find that lauoho o Pele forms at high vesicularity in our experiments, which is consistent with the interiors of high Hawaiian lava fountains, and the surfaces of lava lakes, and proximal and intubated lava flows.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"418 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147319738","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}
Chris D. Fokkema, Tobias Agterhuis, Danielle Gerritsma, Peter K. Bijl, Marlow J. Cramwinckel, Appy Sluijs
Biotic response across the Paleocene−Eocene Thermal Maximum (PETM; 56 Ma) is well documented, but information for other, lower-magnitude, early Eocene transient global warming events (hyperthermals) is sparse. We studied dinoflagellate cyst assemblages across six post-PETM hyperthermals (I1, I2, J, K, L1, and L2; 53.7−52.0 Ma) in the eastern tropical Atlantic Ocean. Remarkably, we observe no assemblage changes associated with the hyperthermals, which starkly contrasts the demise of eukaryotes during the PETM and harmful algal blooms associated with long-term warming during the Middle Eocene Climatic Optimum (ca. 40 Ma) at the same site. However, our results mimic observations of resilient calcareous nannoplankton assemblages to certain lower-magnitude hyperthermals in the tropical Pacific. We conclude that tropical early Eocene phytoplankton communities were resilient to multimillennial-scale warming of up to ∼1.5 °C.
{"title":"Resilient tropical marine ecosystems during early Eocene global warming events","authors":"Chris D. Fokkema, Tobias Agterhuis, Danielle Gerritsma, Peter K. Bijl, Marlow J. Cramwinckel, Appy Sluijs","doi":"10.1130/g54281.1","DOIUrl":"https://doi.org/10.1130/g54281.1","url":null,"abstract":"Biotic response across the Paleocene−Eocene Thermal Maximum (PETM; 56 Ma) is well documented, but information for other, lower-magnitude, early Eocene transient global warming events (hyperthermals) is sparse. We studied dinoflagellate cyst assemblages across six post-PETM hyperthermals (I1, I2, J, K, L1, and L2; 53.7−52.0 Ma) in the eastern tropical Atlantic Ocean. Remarkably, we observe no assemblage changes associated with the hyperthermals, which starkly contrasts the demise of eukaryotes during the PETM and harmful algal blooms associated with long-term warming during the Middle Eocene Climatic Optimum (ca. 40 Ma) at the same site. However, our results mimic observations of resilient calcareous nannoplankton assemblages to certain lower-magnitude hyperthermals in the tropical Pacific. We conclude that tropical early Eocene phytoplankton communities were resilient to multimillennial-scale warming of up to ∼1.5 °C.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"25 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147319739","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}
Jintian Zheng, Shifeng Dai, Victor P. Nechaev, David French, Ian T. Graham, James C. Hower, Jingjing Liu, Shaowei Zhang, Shuai Kang, Mengda Yao, Yang Liang, Yutang Zhang
Coal deposits derived from peat play a key role in Earth’s carbon cycle by facilitating the burial and transformation of organic carbon. However, the role of mineral precipitation in peat-forming environments, particularly the microbially mediated formation of siderite and its contribution to carbon cycling, remains poorly understood. Here, we investigate a Jurassic siderite-bearing coal seam to reconstruct mineral paragenesis and constrain diagenetic conditions during peat accumulation. Authigenic, 13C-rich siderite associated with methanogenesis formed under acidic and reducing conditions, consistent with precipitation equilibrium simulations that show enhanced siderite saturation at elevated CO2 pressures. Our results suggest that siderite genetically associated with coal may have acted as an inorganic carbon sink by limiting greenhouse-gas release during peat decomposition, thereby reducing CO2 emission by 2% within the studied paleo-peat deposit and sequestering ∼12.67 Gt of CO2 across three Jurassic coal basins. These findings reveal a previously overlooked pathway for carbon fixation in coal measures, with potential for both deep-time climate and modern greenhouse gas mitigation.
{"title":"Methanogenesis and siderite precipitation in coal: Significance for carbon sequestration","authors":"Jintian Zheng, Shifeng Dai, Victor P. Nechaev, David French, Ian T. Graham, James C. Hower, Jingjing Liu, Shaowei Zhang, Shuai Kang, Mengda Yao, Yang Liang, Yutang Zhang","doi":"10.1130/g54235.1","DOIUrl":"https://doi.org/10.1130/g54235.1","url":null,"abstract":"Coal deposits derived from peat play a key role in Earth’s carbon cycle by facilitating the burial and transformation of organic carbon. However, the role of mineral precipitation in peat-forming environments, particularly the microbially mediated formation of siderite and its contribution to carbon cycling, remains poorly understood. Here, we investigate a Jurassic siderite-bearing coal seam to reconstruct mineral paragenesis and constrain diagenetic conditions during peat accumulation. Authigenic, 13C-rich siderite associated with methanogenesis formed under acidic and reducing conditions, consistent with precipitation equilibrium simulations that show enhanced siderite saturation at elevated CO2 pressures. Our results suggest that siderite genetically associated with coal may have acted as an inorganic carbon sink by limiting greenhouse-gas release during peat decomposition, thereby reducing CO2 emission by 2% within the studied paleo-peat deposit and sequestering ∼12.67 Gt of CO2 across three Jurassic coal basins. These findings reveal a previously overlooked pathway for carbon fixation in coal measures, with potential for both deep-time climate and modern greenhouse gas mitigation.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"104 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147274367","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：