A. Metcalfe, K. Pank, T.H. Druitt, S. Kutterolf, J. Preine, P. Nomikou, C. Hübscher, T.A. Ronge, Expedition Three-Ninety-Eight Scientists IODP
The histories of submarine explosive volcanoes are commonly poorly known due to inaccessibility of their eruptive archives. This raises uncertainties in the eruption frequencies of these highly hazardous systems, and in their interactions with neighboring volcanoes. The submarine Kolumbo Volcanic Chain (KVC) northeast of Santorini is made up of the polygenetic Kolumbo Volcano and a linear zone of more than 20 smaller volcanic cones and is one of the most active eruptive centers on the South Aegean Volcanic Arc. However, despite the destructive eruption of Kolumbo in 1650 CE, and unrest in 2024−2025, the eruptive history of the KVC is poorly known. International Ocean Discovery Program (IODP) Expedition 398 deep-drilled the seafloor at two sites on the western flank of Kolumbo. Here, we use tephrostratigraphy to identify 19 explosive eruptions of the KVC (probably mostly Kolumbo itself) ranging from basaltic andesite to rhyolite in composition and beginning at ca. 265 ka. The lifespan-averaged recurrence time of explosive activity along the KVC is ∼6 k.y. (but as low as ∼1 k.y. between 178 ka and 164 ka), although many of these eruptions were smaller than that of 1650 CE. The birth of Kolumbo coincided with the transition of Santorini to highly explosive activity, possibly due to joint interactions with regional lithospheric stresses. Moreover, the three main phases of edifice construction at Kolumbo (ca. 265−193 ka, 24 ka, and 0.4 ka) broadly correspond to periods of caldera-forming eruptions at Santorini, reflecting additional couplings between the two volcanic systems on shorter time scales.
{"title":"Temporal linkages of explosive activity of Kolumbo and Santorini Volcanoes (Greece)","authors":"A. Metcalfe, K. Pank, T.H. Druitt, S. Kutterolf, J. Preine, P. Nomikou, C. Hübscher, T.A. Ronge, Expedition Three-Ninety-Eight Scientists IODP","doi":"10.1130/g53965.1","DOIUrl":"https://doi.org/10.1130/g53965.1","url":null,"abstract":"The histories of submarine explosive volcanoes are commonly poorly known due to inaccessibility of their eruptive archives. This raises uncertainties in the eruption frequencies of these highly hazardous systems, and in their interactions with neighboring volcanoes. The submarine Kolumbo Volcanic Chain (KVC) northeast of Santorini is made up of the polygenetic Kolumbo Volcano and a linear zone of more than 20 smaller volcanic cones and is one of the most active eruptive centers on the South Aegean Volcanic Arc. However, despite the destructive eruption of Kolumbo in 1650 CE, and unrest in 2024−2025, the eruptive history of the KVC is poorly known. International Ocean Discovery Program (IODP) Expedition 398 deep-drilled the seafloor at two sites on the western flank of Kolumbo. Here, we use tephrostratigraphy to identify 19 explosive eruptions of the KVC (probably mostly Kolumbo itself) ranging from basaltic andesite to rhyolite in composition and beginning at ca. 265 ka. The lifespan-averaged recurrence time of explosive activity along the KVC is ∼6 k.y. (but as low as ∼1 k.y. between 178 ka and 164 ka), although many of these eruptions were smaller than that of 1650 CE. The birth of Kolumbo coincided with the transition of Santorini to highly explosive activity, possibly due to joint interactions with regional lithospheric stresses. Moreover, the three main phases of edifice construction at Kolumbo (ca. 265−193 ka, 24 ka, and 0.4 ka) broadly correspond to periods of caldera-forming eruptions at Santorini, reflecting additional couplings between the two volcanic systems on shorter time scales.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"88 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115550","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}
Lingxiao Gong, Peter van der Beek, Edward R. Sobel, Taylor F. Schildgen, Apolline Mariotti, Maxime Bernard, Johannes Glodny, Isabel Wapenhans
The relative influence of tectonics and climate on topography and surface processes remains poorly constrained in many mountainous regions. The effect of late-Cenozoic glaciations on global erosion rates and relief is particularly disputed. The Terskey Range, in the Kyrgyz Tian Shan, can provide key insights to these questions due to its well-documented late-Cenozoic tectonic activity and substantial Quaternary glacier cover. To address these questions, we investigated two valleys within the Terskey Range, separated by 40 km: the glacial Barskoon Valley and the mostly fluvial Kyzyl Suu Valley. We present new apatite (U-Th-Sm)/He (AHe) thermochronology data from valley-bottom samples in the Barskoon Valley and re-analyzed published low-temperature thermochronology data for both valleys. Inverse 3-D thermal-kinematic modeling indicates a shared tectonic history for both valleys, including accelerated thrusting starting at 10−8 Ma. In contrast to the Kyzyl Suu Valley, the Barskoon Valley additionally records a 22% increase in relief over the past ∼2 m.y., suggesting rapid valley deepening following the initiation of glaciation in the Terskey Range. These results imply that the impact of Quaternary climate change on erosion rates is highly spatially variable.
{"title":"Late-Cenozoic tectonic versus glacial control on the topographic evolution of the Terskey Range, Kyrgyz Tian Shan","authors":"Lingxiao Gong, Peter van der Beek, Edward R. Sobel, Taylor F. Schildgen, Apolline Mariotti, Maxime Bernard, Johannes Glodny, Isabel Wapenhans","doi":"10.1130/g53908.1","DOIUrl":"https://doi.org/10.1130/g53908.1","url":null,"abstract":"The relative influence of tectonics and climate on topography and surface processes remains poorly constrained in many mountainous regions. The effect of late-Cenozoic glaciations on global erosion rates and relief is particularly disputed. The Terskey Range, in the Kyrgyz Tian Shan, can provide key insights to these questions due to its well-documented late-Cenozoic tectonic activity and substantial Quaternary glacier cover. To address these questions, we investigated two valleys within the Terskey Range, separated by 40 km: the glacial Barskoon Valley and the mostly fluvial Kyzyl Suu Valley. We present new apatite (U-Th-Sm)/He (AHe) thermochronology data from valley-bottom samples in the Barskoon Valley and re-analyzed published low-temperature thermochronology data for both valleys. Inverse 3-D thermal-kinematic modeling indicates a shared tectonic history for both valleys, including accelerated thrusting starting at 10−8 Ma. In contrast to the Kyzyl Suu Valley, the Barskoon Valley additionally records a 22% increase in relief over the past ∼2 m.y., suggesting rapid valley deepening following the initiation of glaciation in the Terskey Range. These results imply that the impact of Quaternary climate change on erosion rates is highly spatially variable.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"15 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115913","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}
Typhoon-induced heavy rainfall profoundly affects coastal society and economies, yet predicting its future remains challenging. Historical typhoon records are crucial for deciphering the mechanisms behind typhoon variability, but they seldom span the entire Holocene Epoch. Given the distinctively negative isotopic signatures of typhoon precipitation, this study examined a Holocene precipitation isotope record derived from the hydrogen isotope composition (δD) of leaf-wax n-alkanes in a lake sediment core from the South China coast to assess its potential for reflecting past typhoon activity. The reconstructed precipitation δD (δDp) values were less negative during 9.2−3.5 ka (1 ka = 1000 calendar yr B.P.) and more negative during 11.2−9.2 ka and 3.5−0 ka, showing an oscillating “negative-positive-negative” pattern. Superimposed on this pattern were millennial-scale negative excursions coinciding with North Atlantic Bond events. Unlike typical East Asian monsoon stalagmite δ18O records, we demonstrate that our δDp record reflects regional typhoon activity at millennial and multi-millennial time scales. It is likely that a weaker Atlantic Meridional Overturning Circulation and larger El Niño amplitude synergistically resulted in stronger typhoon activity and thus more negative δDp values in coastal South China during the early and late Holocene, respectively, as well as during Bond events.
台风引发的强降雨对沿海地区的社会和经济产生了深远的影响，但预测其未来仍具有挑战性。历史上的台风记录对于解释台风变率背后的机制至关重要，但它们很少跨越整个全新世。鉴于台风降水具有明显的负同位素特征，本研究对华南沿海湖泊沉积物岩心中叶蜡正构烷烃氢同位素组成（δD）的全新世降水同位素记录进行了研究，以评估其反映过去台风活动的潜力。重构降水δD （δDp）值在9.2 ~ 3.5 ka （1 ka = 1000历年B.P.）期间负偏小，在11.2 ~ 9.2 ka和3.5 ~ 0 ka期间负偏大，呈现出“负-正-负”的振荡模式。叠加在这一模式上的是与北大西洋债券事件相吻合的千禧年规模的负偏移。与典型的东亚季风石笋δ18O记录不同，我们的δDp记录反映了千年和千年时间尺度上的区域台风活动。全新世早期和晚期以及Bond事件期间，大西洋经向翻转环流的减弱和El Niño振幅的增大可能共同导致了华南沿海台风活动的增强和负δDp值的增加。
{"title":"Pronounced typhoon landfall imprints in the Holocene precipitation isotope record from coastal South China","authors":"Jiantao Cao, Yanming Ruan, Liping Tian, Fajin Chen, Chao Huang, Xiaobo Jin, Zhiguo Rao, Guodong Jia","doi":"10.1130/g53699.1","DOIUrl":"https://doi.org/10.1130/g53699.1","url":null,"abstract":"Typhoon-induced heavy rainfall profoundly affects coastal society and economies, yet predicting its future remains challenging. Historical typhoon records are crucial for deciphering the mechanisms behind typhoon variability, but they seldom span the entire Holocene Epoch. Given the distinctively negative isotopic signatures of typhoon precipitation, this study examined a Holocene precipitation isotope record derived from the hydrogen isotope composition (δD) of leaf-wax n-alkanes in a lake sediment core from the South China coast to assess its potential for reflecting past typhoon activity. The reconstructed precipitation δD (δDp) values were less negative during 9.2−3.5 ka (1 ka = 1000 calendar yr B.P.) and more negative during 11.2−9.2 ka and 3.5−0 ka, showing an oscillating “negative-positive-negative” pattern. Superimposed on this pattern were millennial-scale negative excursions coinciding with North Atlantic Bond events. Unlike typical East Asian monsoon stalagmite δ18O records, we demonstrate that our δDp record reflects regional typhoon activity at millennial and multi-millennial time scales. It is likely that a weaker Atlantic Meridional Overturning Circulation and larger El Niño amplitude synergistically resulted in stronger typhoon activity and thus more negative δDp values in coastal South China during the early and late Holocene, respectively, as well as during Bond events.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"33 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115911","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}
Aeolian transport, in which turbulent wind shearing over a granular bed causes grains to hop or roll along the bed, is a major mechanism controlling bedform evolution and desertification processes. Predictions of transport rates have significantly advanced in recent years, but none of the theoretical models has managed to provide accurate predictions of aeolian transport over a wide range of wind conditions. Here, we develop a theory, based on the physics of different transport regimes, that accounts for the linear and nonlinear scaling exhibited by aeolian sand transport, capturing quantitatively the contribution of these regimes to the total transport for a wide range of wind velocities. Our theoretical predictions are in very good agreement with experimental results for a large range of wind strengths.
{"title":"Derivation of the nonlinear dependence of aeolian sand flux on wind speed","authors":"Peng Wang, Hans J. Herrmann, Ning Huang","doi":"10.1130/g53971.1","DOIUrl":"https://doi.org/10.1130/g53971.1","url":null,"abstract":"Aeolian transport, in which turbulent wind shearing over a granular bed causes grains to hop or roll along the bed, is a major mechanism controlling bedform evolution and desertification processes. Predictions of transport rates have significantly advanced in recent years, but none of the theoretical models has managed to provide accurate predictions of aeolian transport over a wide range of wind conditions. Here, we develop a theory, based on the physics of different transport regimes, that accounts for the linear and nonlinear scaling exhibited by aeolian sand transport, capturing quantitatively the contribution of these regimes to the total transport for a wide range of wind velocities. Our theoretical predictions are in very good agreement with experimental results for a large range of wind strengths.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"1 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115914","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}
Magmatic volatile phases (MVPs) are multicomponent fluids that are a transport medium for metals being transferred from deep magmatic sources to sites of ore formation. However, the melt-to-fluid exchange of metals remains elusive because existing empirical simulations primarily address metal transport through the fate of one chemical element. We use a comprehensive thermochemical model to simulate the fractional crystallization of a silicate melt that degasses a multicomponent MVP. We show that the major and trace element abundances in MVPs formed from non-enriched magmatic systems are indistinguishable from MVPs found as fluid inclusions in mineralized and non-mineralized systems. We therefore conclude that ore formation is the consequence of repetitive intrusion-fractionation-degassing cycles common to crustal systems without pre-enriched sources, as opposed to scenarios wherein a particular or complex chemical system is required. Instead, the driving force of ore formation is a long-lived system fueled by an H2O- and Cl-bearing melt. Variations in metal signatures of fluids therefore reflect the pressure-temperature path of melt ascent and the changes in major element composition of the melt.
{"title":"Metal transport by magmatic volatile phases in crustal systems","authors":"Austin M. Gion, Fabrice Gaillard","doi":"10.1130/g54065.1","DOIUrl":"https://doi.org/10.1130/g54065.1","url":null,"abstract":"Magmatic volatile phases (MVPs) are multicomponent fluids that are a transport medium for metals being transferred from deep magmatic sources to sites of ore formation. However, the melt-to-fluid exchange of metals remains elusive because existing empirical simulations primarily address metal transport through the fate of one chemical element. We use a comprehensive thermochemical model to simulate the fractional crystallization of a silicate melt that degasses a multicomponent MVP. We show that the major and trace element abundances in MVPs formed from non-enriched magmatic systems are indistinguishable from MVPs found as fluid inclusions in mineralized and non-mineralized systems. We therefore conclude that ore formation is the consequence of repetitive intrusion-fractionation-degassing cycles common to crustal systems without pre-enriched sources, as opposed to scenarios wherein a particular or complex chemical system is required. Instead, the driving force of ore formation is a long-lived system fueled by an H2O- and Cl-bearing melt. Variations in metal signatures of fluids therefore reflect the pressure-temperature path of melt ascent and the changes in major element composition of the melt.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"15 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115912","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}
Meng Cheng, Junpeng Zhang, James D. Schiffbauer, Zihu Zhang, Haiyang Wang, Mengcun Cao, Na Li, Matthew S. Dodd, Mikaela A. Pulsipher, Thomas J. Algeo, Mingcai Hou, Chao Li
The late Cambrian Steptoean positive carbon isotope excursion (SPICE) coincided with the end-Marjuman trilobite extinction and an episode of global ocean euxinia. However, the mechanism that sustained euxinia for ∼2−3 m.y. remains unclear. To address this, a novel combination of carbonate-associated phosphorus (CAP) and iodine [I/(Ca + Mg)] ratios was analyzed at four sites representing a range of water depths across the central Missouri intrashelf basin. Our data demonstrate that CAP rose during the SPICE, in parallel with elevated δ13C values and expanded euxinia, indicating increased phosphate availability in the surface ocean. In contrast, I/(Ca + Mg) ratios remained low, demonstrating persistent oxygen-poor conditions in shallow seas. These characteristics can be linked to enhanced phosphorus release and recycling in the ocean due to expanded seafloor euxinia. Based on a coupled oceanic carbon-phosphorus model, we infer that elevated phosphorus levels boosted primary productivity in the surface ocean, leading to increased oxygen generation and enhanced particulate export, sustaining oceanic euxinia until the feedback was broken by rising atmospheric O2 levels. Our study highlights phosphorus recycling as a key driver of late Cambrian ocean redox instability.
{"title":"Enhanced oceanic phosphorus recycling during the Cambrian SPICE event","authors":"Meng Cheng, Junpeng Zhang, James D. Schiffbauer, Zihu Zhang, Haiyang Wang, Mengcun Cao, Na Li, Matthew S. Dodd, Mikaela A. Pulsipher, Thomas J. Algeo, Mingcai Hou, Chao Li","doi":"10.1130/g54063.1","DOIUrl":"https://doi.org/10.1130/g54063.1","url":null,"abstract":"The late Cambrian Steptoean positive carbon isotope excursion (SPICE) coincided with the end-Marjuman trilobite extinction and an episode of global ocean euxinia. However, the mechanism that sustained euxinia for ∼2−3 m.y. remains unclear. To address this, a novel combination of carbonate-associated phosphorus (CAP) and iodine [I/(Ca + Mg)] ratios was analyzed at four sites representing a range of water depths across the central Missouri intrashelf basin. Our data demonstrate that CAP rose during the SPICE, in parallel with elevated δ13C values and expanded euxinia, indicating increased phosphate availability in the surface ocean. In contrast, I/(Ca + Mg) ratios remained low, demonstrating persistent oxygen-poor conditions in shallow seas. These characteristics can be linked to enhanced phosphorus release and recycling in the ocean due to expanded seafloor euxinia. Based on a coupled oceanic carbon-phosphorus model, we infer that elevated phosphorus levels boosted primary productivity in the surface ocean, leading to increased oxygen generation and enhanced particulate export, sustaining oceanic euxinia until the feedback was broken by rising atmospheric O2 levels. Our study highlights phosphorus recycling as a key driver of late Cambrian ocean redox instability.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"4 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089765","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}
Eclogites are generally divided into two types, xenolithic (mantle) and orogenic (crustal). Xenolithic eclogites are late Archean (ca. 3.0−2.5 Ga) or Paleoproterozoic (ca. 2.1−1.7 Ga) in age and are widely interpreted to have been entrained in younger carbonated magmas as they rose through the lithospheric mantle roots of cratons. By contrast, all reliably dated orogenic eclogites are post-Archean, occurring in three periods ca. 2.2−1.7 Ga, 1.2−0.85 Ga, and <0.7 Ga and are generally found in sutures or accretionary complexes. Although the absence of orogenic eclogites from Archean crust may be due to a tectonic mode dominated by plumes, paleomagnetic data from several Archean cratons indicate periods of lithospheric mobility interspersed with periods of stasis, demonstrating differential motions that require active tectonic boundaries between them. The apparent contradiction between a dominantly plume origin for cratonic crust and periods of lithospheric mobility can be reconciled if tectonic units were larger than the preserved cratonic nuclei in a tectonic mode with episodic subduction. The presence of xenolithic eclogites in the mantle roots of cratons suggests that moderate late-stage thickening was driven by convergence during a transition to global plate tectonics. By contrast, the earliest orogenic eclogites occur in sutures between cratons that form the composite continental fragments familiar to the supercontinent cycle.
{"title":"Eclogites and eclogites: Implications for Archean tectonics","authors":"Michael Brown, Sonja Aulbach, Tim Johnson","doi":"10.1130/g54337.1","DOIUrl":"https://doi.org/10.1130/g54337.1","url":null,"abstract":"Eclogites are generally divided into two types, xenolithic (mantle) and orogenic (crustal). Xenolithic eclogites are late Archean (ca. 3.0−2.5 Ga) or Paleoproterozoic (ca. 2.1−1.7 Ga) in age and are widely interpreted to have been entrained in younger carbonated magmas as they rose through the lithospheric mantle roots of cratons. By contrast, all reliably dated orogenic eclogites are post-Archean, occurring in three periods ca. 2.2−1.7 Ga, 1.2−0.85 Ga, and &lt;0.7 Ga and are generally found in sutures or accretionary complexes. Although the absence of orogenic eclogites from Archean crust may be due to a tectonic mode dominated by plumes, paleomagnetic data from several Archean cratons indicate periods of lithospheric mobility interspersed with periods of stasis, demonstrating differential motions that require active tectonic boundaries between them. The apparent contradiction between a dominantly plume origin for cratonic crust and periods of lithospheric mobility can be reconciled if tectonic units were larger than the preserved cratonic nuclei in a tectonic mode with episodic subduction. The presence of xenolithic eclogites in the mantle roots of cratons suggests that moderate late-stage thickening was driven by convergence during a transition to global plate tectonics. By contrast, the earliest orogenic eclogites occur in sutures between cratons that form the composite continental fragments familiar to the supercontinent cycle.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"43 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089738","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}
Juliette Pin, Lydéric France, Gilles Chazot, Etienne Deloule, Mohamed Ahmed Daoud, Bernard Le Gall
Magmatism plays a central role in rift dynamics, yet the structure and evolution of magma plumbing systems during continental break-up remain poorly constrained. The Afar Rift offers a rare opportunity to study active plate divergence and associated magma processes. We investigate the 1978 Ardoukoba fissural eruption in the Asal Rift, a syn-rift volcanism archetypal example and the most recent eruption in this segment of the Afar Rift system. Using a comprehensive dataset of melt inclusion and host mineral compositions, volatile contents (H2O, CO2, δD), and thermobarometry, we reconstruct the transcrustal plumbing system and track magma storage, transfer, and degassing during the eruption. Our results reveal polybaric magma recharge events destabilizing the system, triggering progressive tapping of increasingly deeper mush zones. The eruption began with shallow, evolved melts and transitioned to deeper, more primitive melts and crystal cargos. These findings offer a high-resolution view of magma dynamics during rifting and provide key constraints on the magmatic architecture of incipient oceanic spreading centers.
{"title":"Reactivation of a transcrustal plumbing system during a rifting event (Asal Rift, Djibouti)","authors":"Juliette Pin, Lydéric France, Gilles Chazot, Etienne Deloule, Mohamed Ahmed Daoud, Bernard Le Gall","doi":"10.1130/g53776.1","DOIUrl":"https://doi.org/10.1130/g53776.1","url":null,"abstract":"Magmatism plays a central role in rift dynamics, yet the structure and evolution of magma plumbing systems during continental break-up remain poorly constrained. The Afar Rift offers a rare opportunity to study active plate divergence and associated magma processes. We investigate the 1978 Ardoukoba fissural eruption in the Asal Rift, a syn-rift volcanism archetypal example and the most recent eruption in this segment of the Afar Rift system. Using a comprehensive dataset of melt inclusion and host mineral compositions, volatile contents (H2O, CO2, δD), and thermobarometry, we reconstruct the transcrustal plumbing system and track magma storage, transfer, and degassing during the eruption. Our results reveal polybaric magma recharge events destabilizing the system, triggering progressive tapping of increasingly deeper mush zones. The eruption began with shallow, evolved melts and transitioned to deeper, more primitive melts and crystal cargos. These findings offer a high-resolution view of magma dynamics during rifting and provide key constraints on the magmatic architecture of incipient oceanic spreading centers.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"104 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089747","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}
Jack E. Stirling, Anthony I.S. Kemp, Christopher M. Fisher, Dan Bevan, Steffen G. Hagemann, Cat E. Gill, Elina Kong
The processes governing Li-enrichment of pegmatite magmas to reach spodumene saturation are debated, but recent models advocate that this is achieved by the progressive reworking of Li-rich metasedimentary rocks over several orogenic events. The Proterozoic Aileron Province of the North Australian Craton provides an opportunity to evaluate such models as it is a polydeformed terrane hosting mineralized lithium-cesium-tantalum (LCT) pegmatites. Apatite and cassiterite U-Pb magmatic crystallization ages from the Anningie Pegmatite Field define three distinct stages of pegmatite formation at 1790 Ma, 1750−1740 Ma, and 1725 Ma. These punctuated episodes of pegmatite formation align with three known tectonic events in the North Australian Craton, with supporting geochemical and isotopic data demonstrating that lithium enrichment is driven by the reworking of a Li-rich crustal protolith over multiple orogenic cycles. The Anningie Pegmatite Field represents a real-world example of multi-stage melting processes required to drive lithium enrichment in pegmatite magmas. These results afford a new window into the petrogenesis of LCT pegmatites, allowing for better geodynamic characterization and identification of more robust exploration pathfinders in Proterozoic and Phanerozoic terranes.
{"title":"Geochronological evidence for multi-stage melting in lithium-rich pegmatite formation","authors":"Jack E. Stirling, Anthony I.S. Kemp, Christopher M. Fisher, Dan Bevan, Steffen G. Hagemann, Cat E. Gill, Elina Kong","doi":"10.1130/g54140.1","DOIUrl":"https://doi.org/10.1130/g54140.1","url":null,"abstract":"The processes governing Li-enrichment of pegmatite magmas to reach spodumene saturation are debated, but recent models advocate that this is achieved by the progressive reworking of Li-rich metasedimentary rocks over several orogenic events. The Proterozoic Aileron Province of the North Australian Craton provides an opportunity to evaluate such models as it is a polydeformed terrane hosting mineralized lithium-cesium-tantalum (LCT) pegmatites. Apatite and cassiterite U-Pb magmatic crystallization ages from the Anningie Pegmatite Field define three distinct stages of pegmatite formation at 1790 Ma, 1750−1740 Ma, and 1725 Ma. These punctuated episodes of pegmatite formation align with three known tectonic events in the North Australian Craton, with supporting geochemical and isotopic data demonstrating that lithium enrichment is driven by the reworking of a Li-rich crustal protolith over multiple orogenic cycles. The Anningie Pegmatite Field represents a real-world example of multi-stage melting processes required to drive lithium enrichment in pegmatite magmas. These results afford a new window into the petrogenesis of LCT pegmatites, allowing for better geodynamic characterization and identification of more robust exploration pathfinders in Proterozoic and Phanerozoic terranes.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"62 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089737","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}
Ingo Grevemeyer, Timothy J. Henstock, Milena Marjanović, Cord Papenberg, Anke Dannowski, Yuhan Li, Adam Robinson, Damon A.H. Teagle
Ocean Drilling Program Site 1256 was drilled in the Guatemala Basin, eastern Pacific Ocean, sampling superfast-spreading crust. It is one of the deepest drill holes sampling intact oceanic crust and the only site that has penetrated gabbroic rocks away from a tectonic window. Two gabbroic units were sampled at 1157 m and 1283 m below the basement. We collected seismic refraction and wide-angle reflection data across the drill site, and the resulting tomography models show that the first encountered gabbro does not mark the top of the seismic boundary between the upper (layer 2) and the lower (layer 3) crust, which we observe 500−600 m deeper. We propose that the drilled gabbroic rocks may represent either shallow intrusions or depth variations of the magma lens, marking the upper limit of a layer 2−layer 3 transition zone. Seismic tomography and wide-angle migration of mantle reflections reveal rather thin crust of 5 ± 0.2 km (i.e., ∼1.5 s two-way traveltime), being 1 km thinner than normal oceanic crust. The crustal deficit occurs solely within the lower crust. The observed thin crust distinctly differs from typical fast-spreading crust and may indicate the occurrence of a depleted mantle source. Yet, our preferred interpretation is that at superfast spreading rates of >200 mm/yr, the melt transport through the mantle is too slow to provide enough melts to form 6 km of oceanic crust.
{"title":"Seismic wide-angle constraints on crustal thickness and structure at Ocean Drilling Program Site 1256: How typical are its features for oceanic crust?","authors":"Ingo Grevemeyer, Timothy J. Henstock, Milena Marjanović, Cord Papenberg, Anke Dannowski, Yuhan Li, Adam Robinson, Damon A.H. Teagle","doi":"10.1130/g53824.1","DOIUrl":"https://doi.org/10.1130/g53824.1","url":null,"abstract":"Ocean Drilling Program Site 1256 was drilled in the Guatemala Basin, eastern Pacific Ocean, sampling superfast-spreading crust. It is one of the deepest drill holes sampling intact oceanic crust and the only site that has penetrated gabbroic rocks away from a tectonic window. Two gabbroic units were sampled at 1157 m and 1283 m below the basement. We collected seismic refraction and wide-angle reflection data across the drill site, and the resulting tomography models show that the first encountered gabbro does not mark the top of the seismic boundary between the upper (layer 2) and the lower (layer 3) crust, which we observe 500−600 m deeper. We propose that the drilled gabbroic rocks may represent either shallow intrusions or depth variations of the magma lens, marking the upper limit of a layer 2−layer 3 transition zone. Seismic tomography and wide-angle migration of mantle reflections reveal rather thin crust of 5 ± 0.2 km (i.e., ∼1.5 s two-way traveltime), being 1 km thinner than normal oceanic crust. The crustal deficit occurs solely within the lower crust. The observed thin crust distinctly differs from typical fast-spreading crust and may indicate the occurrence of a depleted mantle source. Yet, our preferred interpretation is that at superfast spreading rates of &gt;200 mm/yr, the melt transport through the mantle is too slow to provide enough melts to form 6 km of oceanic crust.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"66 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089759","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}
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