Pub Date : 2023-11-03DOI: 10.2113/2023/lithosphere_2023_202
Yiping Zhang, Xuanhua Chen, Yannan Wang, Andrew V. Zuza, Jin Zhang, Bing Li, Yongchao Wang, Ye Wang, Kui Liu, Lele Han, Beihang Zhang, Heng Zhao
Abstract The North Huicheng Basin strike-slip fault system is on the northeastern frontier of the Tibetan Plateau and separates the West and East Qinling differential orogeny. However, the deformation mechanism of this strike-slip fault system and its exact tectonic significance are unclear. Here, we carried out systematic field structural analysis, physical analog modeling, and multiproxy geochronological dating to address these issues. The field structural analysis indicates that the North Huicheng Basin strike-slip fault system was induced from the plate-like movement of the West and East Qinling Orogens, which underwent multiple left-lateral strike-slip faulting and controlled salient and recessed structures. The scaled physical analog experiment results confirm this hypothesis and reveal the primary spatial-temporal deformational kinematic process. Combined with published works, multiproxy geochronological dating (zircon U‒Pb age of 213 Ma, biotite 40Ar/39Ar age of 203 Ma, and apatite fission-track age of 56 Ma) outlines the main thermal history of the hanging wall. Based on the above facts, the integrated research suggests that multistage strike-slip faulting played a significant role in the main tectonic events, that is, late Triassic magmatic emplacement, Jurassic/Cretaceous local pull-apart, and Cenozoic rapid exhumation driven by Tibetan Plateau growth.
{"title":"Multistage Strike-Slip Fault in the Narrowest Portion of the Qinling Orogen, Central China: Deformation Mechanism and Tectonic Significance","authors":"Yiping Zhang, Xuanhua Chen, Yannan Wang, Andrew V. Zuza, Jin Zhang, Bing Li, Yongchao Wang, Ye Wang, Kui Liu, Lele Han, Beihang Zhang, Heng Zhao","doi":"10.2113/2023/lithosphere_2023_202","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_202","url":null,"abstract":"Abstract The North Huicheng Basin strike-slip fault system is on the northeastern frontier of the Tibetan Plateau and separates the West and East Qinling differential orogeny. However, the deformation mechanism of this strike-slip fault system and its exact tectonic significance are unclear. Here, we carried out systematic field structural analysis, physical analog modeling, and multiproxy geochronological dating to address these issues. The field structural analysis indicates that the North Huicheng Basin strike-slip fault system was induced from the plate-like movement of the West and East Qinling Orogens, which underwent multiple left-lateral strike-slip faulting and controlled salient and recessed structures. The scaled physical analog experiment results confirm this hypothesis and reveal the primary spatial-temporal deformational kinematic process. Combined with published works, multiproxy geochronological dating (zircon U‒Pb age of 213 Ma, biotite 40Ar/39Ar age of 203 Ma, and apatite fission-track age of 56 Ma) outlines the main thermal history of the hanging wall. Based on the above facts, the integrated research suggests that multistage strike-slip faulting played a significant role in the main tectonic events, that is, late Triassic magmatic emplacement, Jurassic/Cretaceous local pull-apart, and Cenozoic rapid exhumation driven by Tibetan Plateau growth.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"30 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135818454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-03DOI: 10.2113/2023/lithosphere_2023_218
Hongtao Wang, Shichao Li, Lingyu Zhang, Thomas C. Sheldrick, Fangbin Liu, Zheren Zhao, Xiaopeng Yang, Yadong Wang
Abstract The Greater Khingan Mountains (GKMs) are a prominent orogenic zone in Northeast Asia that offers significant insights into the evolution of the Mongol-Okhotsk Ocean and the Pacific Ocean during the Phanerozoic. A comprehensive study integrating a low-temperature thermochronology analysis pertaining to the Greater Khingan area and its associated basins has been conducted. Apatite fission-track (AFT) tests conducted on detrital samples from the GKMs in Northeast China have yielded central ages ranging from 260 to 62 Ma. Two-dimensional thermal history inversion modeling and three-dimensional numerical simulations were used to investigate the GKMs' thermal history, revealing at least two distinct tectonic cooling and exhumation events: one occurring between 147 and 70 Ma and another around 35 Ma. The fission-track age groups of the GKMs, Hailar-Erlian Basin, and Mohe Basin bear some resemblance (>105 Ma), but the results from the Songliao Basin are unique. This implies that the Songliao Basin and the GKMs were likely under the influence of different tectonic domains during this period, while AFT age peaks between 105 and 45 Ma, indicating the basin-mountain systems were likely influenced by a unified Paleo-Pacific plate process, which prevailed from about 105 Ma. The 147–70 Ma cooling event can be attributed to the combined effects of the compression orogeny, resulting from the closure of the Mongol-Okhotsk Ocean during the Early Cretaceous and the extension orogeny triggered by the subduction of the Paleo-Pacific Ocean during the early Late Cretaceous. Since approximately 35 Ma, the increase in Pacific plate subduction speed may have established a post-arc extensional tectonic environment in the GKMs that has persisted until now.
{"title":"Exhumation History of the Greater Khingan Mountains (NE China) Since the Late Mesozoic: Implications for the Tectonic Regime Change of Northeast Asia","authors":"Hongtao Wang, Shichao Li, Lingyu Zhang, Thomas C. Sheldrick, Fangbin Liu, Zheren Zhao, Xiaopeng Yang, Yadong Wang","doi":"10.2113/2023/lithosphere_2023_218","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_218","url":null,"abstract":"Abstract The Greater Khingan Mountains (GKMs) are a prominent orogenic zone in Northeast Asia that offers significant insights into the evolution of the Mongol-Okhotsk Ocean and the Pacific Ocean during the Phanerozoic. A comprehensive study integrating a low-temperature thermochronology analysis pertaining to the Greater Khingan area and its associated basins has been conducted. Apatite fission-track (AFT) tests conducted on detrital samples from the GKMs in Northeast China have yielded central ages ranging from 260 to 62 Ma. Two-dimensional thermal history inversion modeling and three-dimensional numerical simulations were used to investigate the GKMs' thermal history, revealing at least two distinct tectonic cooling and exhumation events: one occurring between 147 and 70 Ma and another around 35 Ma. The fission-track age groups of the GKMs, Hailar-Erlian Basin, and Mohe Basin bear some resemblance (>105 Ma), but the results from the Songliao Basin are unique. This implies that the Songliao Basin and the GKMs were likely under the influence of different tectonic domains during this period, while AFT age peaks between 105 and 45 Ma, indicating the basin-mountain systems were likely influenced by a unified Paleo-Pacific plate process, which prevailed from about 105 Ma. The 147–70 Ma cooling event can be attributed to the combined effects of the compression orogeny, resulting from the closure of the Mongol-Okhotsk Ocean during the Early Cretaceous and the extension orogeny triggered by the subduction of the Paleo-Pacific Ocean during the early Late Cretaceous. Since approximately 35 Ma, the increase in Pacific plate subduction speed may have established a post-arc extensional tectonic environment in the GKMs that has persisted until now.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"31 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135818589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-03DOI: 10.2113/2023/lithosphere_2023_210
Bin Zhang, Jing Yang, Li Yang, Hong Chen, Jiaqi Liu, Fei Wang, Lin Wu
Abstract The Tianshan Mountains, which formed through the prolonged and complex subduction-accretion of the paleo-Asian ocean, experienced multiple widespread erosions and reactivations during the Mesozoic-Cenozoic period. Thus, the Tianshan has become a crucial area to explore the process and mechanism of intracontinental orogeny. The Harlik Mountain located in the easternmost part of Tianshan has special significance in revealing crustal deformation and far-field stress propagation. In this study, we use the apatite (U-Th)/He method to investigate the near-surface exhumation process of Harlik Mountain, which is the result of tectonic events and erosion. The apatite (U-Th)/He data and thermal history modeling reveal three enhanced exhumation events in the Harlik Mountain, i.e., the early Cretaceous, the late Cretaceous-Paleocene, and the middle Eocene. These events are consistent with the exhumation patterns observed throughout the entire Tianshan. Notably, the exhumation rate and amplitude in the early Cenozoic period were significantly higher in the Harlik Mountain compared with the Mesozoic period. Our findings reveal that the exhumation of the Harlik Mountain and the entire Tianshan displayed pronounced spatial-temporal variations throughout the Mesozoic-Cenozoic period. These variations can be attributed to the combined effect of uneven northward compression of the southern Asian margin, the heterogeneous rheological properties of the lithosphere, and the complex structure of the Tianshan.
{"title":"Mesozoic-Cenozoic Exhumation Processes of the Harlik Mountain (East Tianshan), NW China: Evidence from Apatite (U-Th)/He Thermochronology","authors":"Bin Zhang, Jing Yang, Li Yang, Hong Chen, Jiaqi Liu, Fei Wang, Lin Wu","doi":"10.2113/2023/lithosphere_2023_210","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_210","url":null,"abstract":"Abstract The Tianshan Mountains, which formed through the prolonged and complex subduction-accretion of the paleo-Asian ocean, experienced multiple widespread erosions and reactivations during the Mesozoic-Cenozoic period. Thus, the Tianshan has become a crucial area to explore the process and mechanism of intracontinental orogeny. The Harlik Mountain located in the easternmost part of Tianshan has special significance in revealing crustal deformation and far-field stress propagation. In this study, we use the apatite (U-Th)/He method to investigate the near-surface exhumation process of Harlik Mountain, which is the result of tectonic events and erosion. The apatite (U-Th)/He data and thermal history modeling reveal three enhanced exhumation events in the Harlik Mountain, i.e., the early Cretaceous, the late Cretaceous-Paleocene, and the middle Eocene. These events are consistent with the exhumation patterns observed throughout the entire Tianshan. Notably, the exhumation rate and amplitude in the early Cenozoic period were significantly higher in the Harlik Mountain compared with the Mesozoic period. Our findings reveal that the exhumation of the Harlik Mountain and the entire Tianshan displayed pronounced spatial-temporal variations throughout the Mesozoic-Cenozoic period. These variations can be attributed to the combined effect of uneven northward compression of the southern Asian margin, the heterogeneous rheological properties of the lithosphere, and the complex structure of the Tianshan.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"30 33","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135818597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bo Liang, Yuangang Liu, Zhexian Su, Naidan Zhang, Shaohua Li, Wenjie Feng
Abstract Collecting information about fracture attributes through outcrops measurement is crucial for analyzing the scale, distribution, orientation, and spatial arrangement of fractures. The emergence of digital outcrop models (DOMs) provides a new technology for quantitative interpretation of fractures. However, large-scale DOMs pose additional challenges to the practical application, particularly in the interpretation of geological elements (e.g. fractures). This research proposes a workflow for fracture characteristics interpretation based on DOMs. First, DOMs are generated using light detection and ranging scanning technology. Then, a 3D visualization platform is developed based on OpenSceneGraph. We use level-of-detail technology to reconstruct DOMs for multiscale fast visualization of large-scale models. Finally, in order to realize the quantitative interpretation of fractures, we propose the best-plane fitting and the feature information (orientation, length, spacing, etc.) extraction methods for two types of fractures (exposed fracture walls and fracture traces). The proposed methods are applied to extract attributes of fractures in Dengying Formation (second member), Ebian, Xianfeng, southwest Sichuan Basin, China. The results provide the basis for reservoir evaluation in this area.
{"title":"A Workflow for Interpretation of Fracture Characteristics Based on Digital Outcrop Models: A Case Study on Ebian XianFeng Profile in Sichuan Basin","authors":"Bo Liang, Yuangang Liu, Zhexian Su, Naidan Zhang, Shaohua Li, Wenjie Feng","doi":"10.2113/2022/7456300","DOIUrl":"https://doi.org/10.2113/2022/7456300","url":null,"abstract":"Abstract Collecting information about fracture attributes through outcrops measurement is crucial for analyzing the scale, distribution, orientation, and spatial arrangement of fractures. The emergence of digital outcrop models (DOMs) provides a new technology for quantitative interpretation of fractures. However, large-scale DOMs pose additional challenges to the practical application, particularly in the interpretation of geological elements (e.g. fractures). This research proposes a workflow for fracture characteristics interpretation based on DOMs. First, DOMs are generated using light detection and ranging scanning technology. Then, a 3D visualization platform is developed based on OpenSceneGraph. We use level-of-detail technology to reconstruct DOMs for multiscale fast visualization of large-scale models. Finally, in order to realize the quantitative interpretation of fractures, we propose the best-plane fitting and the feature information (orientation, length, spacing, etc.) extraction methods for two types of fractures (exposed fracture walls and fracture traces). The proposed methods are applied to extract attributes of fractures in Dengying Formation (second member), Ebian, Xianfeng, southwest Sichuan Basin, China. The results provide the basis for reservoir evaluation in this area.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135927892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-30DOI: 10.2113/2023/lithosphere_2023_110
Kuruvamana Satheeshbabu Sreenidhi, Munukutla Radhakrishna, Peter G. Betts
Abstract The Red Sea provides an opportunity to study the processes during the transition from continental rifting to early-stage seafloor spreading during ocean initiation. We delineate variations of lithospheric architecture and the nature of extension along the Red Sea region through joint interpretation of gravity and geoid anomalies and gravity-topography transfer functions. We use lithospheric-scale models to compare stretching factors with upper mantle gravity anomaly, residual mantle Bouguer anomaly, and effective elastic thickness. Based on our observations, the Red Sea is divided into four segments; each having distinct lithospheric characteristics and stretching styles. These are: (i) southernmost Red Sea and Danakil having regionally weak and stretched lithosphere, (ii) southern Red Sea with fully developed seafloor spreading and asymmetric lithospheric architecture, (iii) central Red Sea having discontinuous magma accretion with newly formed seafloor spreading, and (iv) northern Red sea with a stronger lithosphere and limited stretching revealing a stage of continental rifting. In these segments, lithospheric stretching correlates with regions of weak lithosphere, including a regime of sublithospheric plume channel beneath the southern Red Sea. The Zabargad fracture zone between the central and northern segments is revealed as a major lithosphere-scale boundary that may act as a barrier to the propagation of seafloor spreading into the northern Red Sea. The weak and highly stretched lithosphere in this region may indicate the onset of a new spreading cell. Our results conclude that the evolution of the Red Sea is more complex than the previously suggested kinematic models of simple “unzipping” and illustrate that several extensional styles can exist within different segments during the initial stages of ocean formation.
{"title":"Lithospheric Structure and Extensional Style of the Red Sea Rift Segments","authors":"Kuruvamana Satheeshbabu Sreenidhi, Munukutla Radhakrishna, Peter G. Betts","doi":"10.2113/2023/lithosphere_2023_110","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_110","url":null,"abstract":"Abstract The Red Sea provides an opportunity to study the processes during the transition from continental rifting to early-stage seafloor spreading during ocean initiation. We delineate variations of lithospheric architecture and the nature of extension along the Red Sea region through joint interpretation of gravity and geoid anomalies and gravity-topography transfer functions. We use lithospheric-scale models to compare stretching factors with upper mantle gravity anomaly, residual mantle Bouguer anomaly, and effective elastic thickness. Based on our observations, the Red Sea is divided into four segments; each having distinct lithospheric characteristics and stretching styles. These are: (i) southernmost Red Sea and Danakil having regionally weak and stretched lithosphere, (ii) southern Red Sea with fully developed seafloor spreading and asymmetric lithospheric architecture, (iii) central Red Sea having discontinuous magma accretion with newly formed seafloor spreading, and (iv) northern Red sea with a stronger lithosphere and limited stretching revealing a stage of continental rifting. In these segments, lithospheric stretching correlates with regions of weak lithosphere, including a regime of sublithospheric plume channel beneath the southern Red Sea. The Zabargad fracture zone between the central and northern segments is revealed as a major lithosphere-scale boundary that may act as a barrier to the propagation of seafloor spreading into the northern Red Sea. The weak and highly stretched lithosphere in this region may indicate the onset of a new spreading cell. Our results conclude that the evolution of the Red Sea is more complex than the previously suggested kinematic models of simple “unzipping” and illustrate that several extensional styles can exist within different segments during the initial stages of ocean formation.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"37 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136023106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-30DOI: 10.2113/2023/lithosphere_2023_176
Jianzhou Tang, Zhicheng Zhang, Zejia Ji
Abstract The Permo-Carboniferous tectonic evolution in the Uliastai continental margin (UCM), north of the southeast central Asian Orogenic Belt, remains controversial. This work examined the geochemical composition of the felsic volcanic rocks from the lower and upper part of the Baoligaomiao Formation in the UCM. Zircon U-Pb ages reveal that the Baoligaomiao Formation has a long-lived eruption duration, from ca. 285 to 328 Ma. The lower part (ca. 328–310 Ma) of the Baoligaomiao Formation is dominated by clastic and pyroclastic rocks with subordinate intermediate-felsic volcanic rocks, whereas the upper part (ca. 307–285 Ma) mainly consists of felsic volcanic rocks and pyroclastic rocks. Calculations reveal that the felsic volcanic rocks from the lower part have low zircon saturation temperatures (TZr = 747℃–795℃), whereas those from the upper part exhibit high TZr (ca. 793℃–930℃). Zircons from the lower part exhibit high εHf(t) values and 176Lu/177Hf ratios, in contrast to the low εHf(t) values and 176Lu/177Hf ratios of zircons from the upper part. Those petrogeological and geochemical shifts might support the tectonic switch model in the UCM at the end of the Carboniferous, providing new constraints on the Late Carboniferous closure of the Hegenshan Ocean.
{"title":"Geochemical Composition Variations and Tectonic Implications of the Baoligaomiao Formation Volcanic Rocks from the Uliastai Continental Margin, Southeast Central Asian Orogenic Belt","authors":"Jianzhou Tang, Zhicheng Zhang, Zejia Ji","doi":"10.2113/2023/lithosphere_2023_176","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_176","url":null,"abstract":"Abstract The Permo-Carboniferous tectonic evolution in the Uliastai continental margin (UCM), north of the southeast central Asian Orogenic Belt, remains controversial. This work examined the geochemical composition of the felsic volcanic rocks from the lower and upper part of the Baoligaomiao Formation in the UCM. Zircon U-Pb ages reveal that the Baoligaomiao Formation has a long-lived eruption duration, from ca. 285 to 328 Ma. The lower part (ca. 328–310 Ma) of the Baoligaomiao Formation is dominated by clastic and pyroclastic rocks with subordinate intermediate-felsic volcanic rocks, whereas the upper part (ca. 307–285 Ma) mainly consists of felsic volcanic rocks and pyroclastic rocks. Calculations reveal that the felsic volcanic rocks from the lower part have low zircon saturation temperatures (TZr = 747℃–795℃), whereas those from the upper part exhibit high TZr (ca. 793℃–930℃). Zircons from the lower part exhibit high εHf(t) values and 176Lu/177Hf ratios, in contrast to the low εHf(t) values and 176Lu/177Hf ratios of zircons from the upper part. Those petrogeological and geochemical shifts might support the tectonic switch model in the UCM at the end of the Carboniferous, providing new constraints on the Late Carboniferous closure of the Hegenshan Ocean.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"162 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136104325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The mechanical characteristics of columnar jointed basalts (CJBs) are generally considered to be subject to size effects. They display complex mechanical behaviors under lateral pressure, which may be related to the variation in the rock's mesoproperties. In this study, many nonuniform CJB models with various rock meso-constitutive relations and model sizes were established, and their influences on the strength and deformation properties, multistage mechanical damage behavior, and acoustic emission characteristics of CJBs were investigated. The results show that, as the residual strength coefficient increases, the compressive strength of CJBs rises, and the equivalent deformation modulus of CJBs decreases or increases slightly; with an increase in the model size, the compressive strength slightly decreases at first and then varies moderately, and the equivalent deformation modulus shows a fluctuating trend. Furthermore, the macro stress–strain relationships can be divided into different stages according to the corresponding damage behaviors. The strains and energy accumulations before peak stress was reached were further analyzed. The results greatly improve our understanding of the collapse process of CJBs and the instability precursors of related structures.
{"title":"Investigation into the Multistage Mechanical Damage Behavior of Columnar Jointed Basalts with Different Meso-Constitutive Relations and Model Sizes","authors":"Yongyi Wang, Bin Gong, Xiaoyu Yang, Chun’an Tang","doi":"10.2113/2023/8711959","DOIUrl":"https://doi.org/10.2113/2023/8711959","url":null,"abstract":"Abstract The mechanical characteristics of columnar jointed basalts (CJBs) are generally considered to be subject to size effects. They display complex mechanical behaviors under lateral pressure, which may be related to the variation in the rock's mesoproperties. In this study, many nonuniform CJB models with various rock meso-constitutive relations and model sizes were established, and their influences on the strength and deformation properties, multistage mechanical damage behavior, and acoustic emission characteristics of CJBs were investigated. The results show that, as the residual strength coefficient increases, the compressive strength of CJBs rises, and the equivalent deformation modulus of CJBs decreases or increases slightly; with an increase in the model size, the compressive strength slightly decreases at first and then varies moderately, and the equivalent deformation modulus shows a fluctuating trend. Furthermore, the macro stress–strain relationships can be divided into different stages according to the corresponding damage behaviors. The strains and energy accumulations before peak stress was reached were further analyzed. The results greatly improve our understanding of the collapse process of CJBs and the instability precursors of related structures.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"40 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135568011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-17DOI: 10.2113/2023/lithosphere_2023_126
Anton Kutyrev, Vadim S. Kamenetsky, Alkiviadis Kontonikas-Charos, Dmitry P. Savelyev, Tamara Yu. Yakich, Ivan A. Belousov, Elena I. Sandimirova, Svetlana V. Moskaleva
Abstract Natural Fe-Ni alloys are common in meteorites and, presumably, the Earth’s core, where they host significant platinum-group elements (PGE). However, little is known on PGE concentrations in hydrothermal or metamorphic Fe-Ni alloys (i.e., awaruite Ni3Fe) from terrestrial rocks. In this work, we examine the geochemistry of awaruite and related minerals from several placer deposits sourced from the suprasubduction ophiolitic (Kamchatsky Mys, Karaginsky Island, and Mamet) and Ural-Alaskan (Galmoenan) complexes of Kamchatka and the Koryak Highlands (Far East Russia) in order to assess the abundance of PGE in awaruite and constrain their mobility under metamorphic and hydrothermal conditions. Studied awaruite from ophiolitic and Ural-Alaskan type complexes formed via desulfurization of pentlandite during serpentinization. Three groups of platinum-group minerals (PGMs) are associated with awaruite from Kamchatsky Mys: (1) Pt-Fe alloys such as ferronickelplatinum (Pt2FeNi) or unnamed Ni2FePt alloys; (2) Os-Ir-Ru alloys of various composition; (3) Pd-Sb minerals which form together with serpentine during hydrothermal alteration. Despite the abundance of PGM inclusions, no significant PGE concentrations were measured in awaruite from the Kamchatsky Mys, Karaginsky Island, or Mamet ophiolites. In contrast, pentlandite relicts in awaruite from placers related to the Galmoenan Ural-Alaskan type complex contain exceptionally high, previously unreported, Os (up to 540 ppm). Awaruite that forms on behalf of this pentlandite does not show any significant Os enrichment. Rare Galmoenan awaruite analyses yield up to 3 ppm Pd. The new data are not in complete accordance with previous studies that reported relatively high (up to first 10 ppm) PGE content in awaruite. We attribute this to low PGE concentration in precursor sulfides and preferential partitioning of PGE into discrete secondary PGM within awaruite. Nevertheless, abundant inclusions of secondary PGM in awaruite provide evidence of PGE mobility during metamorphic and hydrothermal alteration of ultramafic rocks.
{"title":"Behavior of Platinum-Group Elements during Hydrous Metamorphism: Constraints from Awaruite (Ni3Fe) Mineralization","authors":"Anton Kutyrev, Vadim S. Kamenetsky, Alkiviadis Kontonikas-Charos, Dmitry P. Savelyev, Tamara Yu. Yakich, Ivan A. Belousov, Elena I. Sandimirova, Svetlana V. Moskaleva","doi":"10.2113/2023/lithosphere_2023_126","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_126","url":null,"abstract":"Abstract Natural Fe-Ni alloys are common in meteorites and, presumably, the Earth’s core, where they host significant platinum-group elements (PGE). However, little is known on PGE concentrations in hydrothermal or metamorphic Fe-Ni alloys (i.e., awaruite Ni3Fe) from terrestrial rocks. In this work, we examine the geochemistry of awaruite and related minerals from several placer deposits sourced from the suprasubduction ophiolitic (Kamchatsky Mys, Karaginsky Island, and Mamet) and Ural-Alaskan (Galmoenan) complexes of Kamchatka and the Koryak Highlands (Far East Russia) in order to assess the abundance of PGE in awaruite and constrain their mobility under metamorphic and hydrothermal conditions. Studied awaruite from ophiolitic and Ural-Alaskan type complexes formed via desulfurization of pentlandite during serpentinization. Three groups of platinum-group minerals (PGMs) are associated with awaruite from Kamchatsky Mys: (1) Pt-Fe alloys such as ferronickelplatinum (Pt2FeNi) or unnamed Ni2FePt alloys; (2) Os-Ir-Ru alloys of various composition; (3) Pd-Sb minerals which form together with serpentine during hydrothermal alteration. Despite the abundance of PGM inclusions, no significant PGE concentrations were measured in awaruite from the Kamchatsky Mys, Karaginsky Island, or Mamet ophiolites. In contrast, pentlandite relicts in awaruite from placers related to the Galmoenan Ural-Alaskan type complex contain exceptionally high, previously unreported, Os (up to 540 ppm). Awaruite that forms on behalf of this pentlandite does not show any significant Os enrichment. Rare Galmoenan awaruite analyses yield up to 3 ppm Pd. The new data are not in complete accordance with previous studies that reported relatively high (up to first 10 ppm) PGE content in awaruite. We attribute this to low PGE concentration in precursor sulfides and preferential partitioning of PGE into discrete secondary PGM within awaruite. Nevertheless, abundant inclusions of secondary PGM in awaruite provide evidence of PGE mobility during metamorphic and hydrothermal alteration of ultramafic rocks.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136037584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-17DOI: 10.2113/2023/lithosphere_2023_214
Jacek Futrzyński, Rafał Juroszek, Katarzyna Skrzyńska, Yevgeny Vapnik, Evgeny Galuskin
Abstract A new genetic type of chromium garnet—uvarovite with the simplified formula Ca3(Cr,Al,Ti4+,V3+)2(Si,Al)3O12—was detected in unusual wollastonite-gehlenite-bearing paralava within the Hatrurim Complex in Israel. The pyrometamorphic rocks of that Complex usually formed in the sanidinite facies (low pressure and high temperature) and, as a rule, under oxidized conditions. This paralava contains nodules and grain aggregates of native Fe, usually distributed linearly in the rock or located close to gaseous voids. The presence of native iron droplets in association with the “meteoric” phosphide—schreibersite, suggests that the formation of paralava occurred under high-reducing conditions and high temperature, reaching 1500°C. Uvarovite forms xenomorphic grains either randomly distributed within the rock or flattened crystals on the walls of gaseous voids. Analyzed uvarovite indicates a significant enrichment in Ti4+ (up to 8 wt.% TiO2) and V3+ (up to 4.5 wt.% V2O3), the highest concentrations documented for uvarovite. Unlike known uvarovite from different localities, uvarovite from this study does not contain Fe3+, and Fe2+ is present in insignificant amounts. The obtained structural data reveal that the high contribution of hutcheonite, Ca3Ti4+2SiAl2O12 (up to 18%), and goldmanite, Ca3V3+2Si3O12 (up to 11%), end-members increases the lattice parameter a to >12.00 Å. The crystallization of uvarovite occurs in the narrow interval of oxygen fugacity, a little above the iron-wüstite buffer ƒO2 ≥ ΔIW. Uvarovite xenomorphic grains formed due to the decomposition of wollastonite and chromite, including H2S from the intergranular melt/fluid according to the following reaction: Ca3Si3O9 + Fe2+Cr3+2O4 + H2S → Ca3Cr2Si3O12 + FeS + H2O, while the flattened crystals grew from specific melt that formed on the walls of the voids as a result of exposure of hot gas flow. The comparison of the obtained results with available chemical data from previous studies reveals a gap in the natural isomorphic series between andradite and uvarovite.
{"title":"Uvarovite from Reduced Native Fe-Bearing Paralava, Hatrurim Complex, Israel","authors":"Jacek Futrzyński, Rafał Juroszek, Katarzyna Skrzyńska, Yevgeny Vapnik, Evgeny Galuskin","doi":"10.2113/2023/lithosphere_2023_214","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_214","url":null,"abstract":"Abstract A new genetic type of chromium garnet—uvarovite with the simplified formula Ca3(Cr,Al,Ti4+,V3+)2(Si,Al)3O12—was detected in unusual wollastonite-gehlenite-bearing paralava within the Hatrurim Complex in Israel. The pyrometamorphic rocks of that Complex usually formed in the sanidinite facies (low pressure and high temperature) and, as a rule, under oxidized conditions. This paralava contains nodules and grain aggregates of native Fe, usually distributed linearly in the rock or located close to gaseous voids. The presence of native iron droplets in association with the “meteoric” phosphide—schreibersite, suggests that the formation of paralava occurred under high-reducing conditions and high temperature, reaching 1500°C. Uvarovite forms xenomorphic grains either randomly distributed within the rock or flattened crystals on the walls of gaseous voids. Analyzed uvarovite indicates a significant enrichment in Ti4+ (up to 8 wt.% TiO2) and V3+ (up to 4.5 wt.% V2O3), the highest concentrations documented for uvarovite. Unlike known uvarovite from different localities, uvarovite from this study does not contain Fe3+, and Fe2+ is present in insignificant amounts. The obtained structural data reveal that the high contribution of hutcheonite, Ca3Ti4+2SiAl2O12 (up to 18%), and goldmanite, Ca3V3+2Si3O12 (up to 11%), end-members increases the lattice parameter a to >12.00 Å. The crystallization of uvarovite occurs in the narrow interval of oxygen fugacity, a little above the iron-wüstite buffer ƒO2 ≥ ΔIW. Uvarovite xenomorphic grains formed due to the decomposition of wollastonite and chromite, including H2S from the intergranular melt/fluid according to the following reaction: Ca3Si3O9 + Fe2+Cr3+2O4 + H2S → Ca3Cr2Si3O12 + FeS + H2O, while the flattened crystals grew from specific melt that formed on the walls of the voids as a result of exposure of hot gas flow. The comparison of the obtained results with available chemical data from previous studies reveals a gap in the natural isomorphic series between andradite and uvarovite.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136039742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.2113/2023/lithosphere_2023_190
Dunfeng Xiang, Zhiyong Zhang, David Chew, Marc Jolivet, Marco G. Malusà, Chao Guo, Nan Wang, Wenjiao Xiao
Abstract The present-day topography of Tianshan is the product of repeated phases of Meso-Cenozoic intracontinental deformation and reactivation, whereas the long-term Mesozoic topographic evolution and the timing of the onset of Cenozoic deformation remain debated. New insights into the Meso-Cenozoic geodynamic evolution and related basin-range interactions in the Tianshan were obtained based on new detrital single-grain apatite U-Pb, fission-track, and trace-element provenance data from Mesozoic sedimentary sequences on the northern margin of the Tarim Basin. Detrital apatite U-Pb age data from Early-Middle Triassic clastic rocks show two prominent age populations at 500–390 Ma and 330–260 Ma, with a paucity of ages between 390 and 330 Ma, suggesting that sediment source is predominantly from the northern Tarim and South Tianshan. From the Late Triassic to Early Jurassic, the first appearance of populations in the 390–330 Ma and 260–220 age ranges indicates that the Central Tianshan-Yili Block and Western Kunlun Orogen were source regions for the northern margin of Tarim Basin. In the Cretaceous strata, south-directed paleocurrents combined with the decrease in the 390–330 Ma age population from the Central Tianshan-Yili Block imply that South Tianshan was uplifted and again became the main source region to the Baicheng-Kuqa depression during the Cretaceous. Our new apatite fission-track data from the southern Chinese Tianshan suggest that rapid cooling commenced at c. 30 Ma along the southern margin, and the Early Mesozoic strata exposed on the southern flank of the Tianshan underwent c. 4–5 km of late Cenozoic exhumation during this period. This age is approximately synchronous with the onset of exhumation/deformation not only in the whole Tianshan but also in the interior of the Tibetan Plateau and its margins. It suggests that far-field, N-directed shortening resulting from the India-Asia collision was transmitted to the Tianshan at that time.
{"title":"Mesozoic-Cenozoic Topographic Evolution of the South Tianshan (NW China): Insights from Detrital Apatite Geo-Thermochronological and Geochemical Analyses","authors":"Dunfeng Xiang, Zhiyong Zhang, David Chew, Marc Jolivet, Marco G. Malusà, Chao Guo, Nan Wang, Wenjiao Xiao","doi":"10.2113/2023/lithosphere_2023_190","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_190","url":null,"abstract":"Abstract The present-day topography of Tianshan is the product of repeated phases of Meso-Cenozoic intracontinental deformation and reactivation, whereas the long-term Mesozoic topographic evolution and the timing of the onset of Cenozoic deformation remain debated. New insights into the Meso-Cenozoic geodynamic evolution and related basin-range interactions in the Tianshan were obtained based on new detrital single-grain apatite U-Pb, fission-track, and trace-element provenance data from Mesozoic sedimentary sequences on the northern margin of the Tarim Basin. Detrital apatite U-Pb age data from Early-Middle Triassic clastic rocks show two prominent age populations at 500–390 Ma and 330–260 Ma, with a paucity of ages between 390 and 330 Ma, suggesting that sediment source is predominantly from the northern Tarim and South Tianshan. From the Late Triassic to Early Jurassic, the first appearance of populations in the 390–330 Ma and 260–220 age ranges indicates that the Central Tianshan-Yili Block and Western Kunlun Orogen were source regions for the northern margin of Tarim Basin. In the Cretaceous strata, south-directed paleocurrents combined with the decrease in the 390–330 Ma age population from the Central Tianshan-Yili Block imply that South Tianshan was uplifted and again became the main source region to the Baicheng-Kuqa depression during the Cretaceous. Our new apatite fission-track data from the southern Chinese Tianshan suggest that rapid cooling commenced at c. 30 Ma along the southern margin, and the Early Mesozoic strata exposed on the southern flank of the Tianshan underwent c. 4–5 km of late Cenozoic exhumation during this period. This age is approximately synchronous with the onset of exhumation/deformation not only in the whole Tianshan but also in the interior of the Tibetan Plateau and its margins. It suggests that far-field, N-directed shortening resulting from the India-Asia collision was transmitted to the Tianshan at that time.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"208 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135484766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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