Journal of Asian Earth Sciences最新文献

A study of crustal deformation beneath the Qinling Orogenic belt, Central China based on receiver function data 基于接收函数数据的华中秦岭造山带地壳变形研究

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-10 DOI: 10.1016/j.jseaes.2024.106404

Ya Sun , Yangyi Deng , Syed-Muzyan Shahzad , Bo Chen

A joint shear wave splitting technique based on receiver function data is employed to invert the crustal anisotropy, Moho depth, and Vp/Vs ratio in the Qinling Orogenic belt (QOB). Our findings reveal a relatively low Vp/Vs ratio (∼1.74) and a thin crust in east QOB. This suggests that potential crustal flow from central Tibet may not significantly influence the crustal deformation in east QOB. Our results demonstrate high Vp/Vs ratios (∼1.75–1.88), thick crust (∼44–56 km), and significant crustal anisotropy with a delay time of 0.22–0.86 s in south QOB, Dabashan, and west QOB regions. The fast directions of crustal anisotropy in the south QOB and Dabashan areas are NW-SE, which reflect the orientation of crustal fabrics associated with the collision between the North China Block and the South China Block. However, weak or negligible splitting times are observed beneath the Shennongjia-Huangling (SNHL), Hannan-Micang (HNMC) domes, and Jianghan Basin. The presence of weak crustal anisotropy is likely related to the stable basements beneath two domes, while the negligible splitting time beneath the Jianghan Basin might be attributed to the nearly vertical α-axis of olivines or mica associated with a subvertical mantle flow caused by slab break-off of the subducted Yangtze Block. The underlying magmas have gathered in the lower crust and formed the mafic lower crust, which cause an increase in the crust Vp/Vs ratio and crustal extension.

基于接收函数数据的联合剪切波分裂技术反演了秦岭造山带（QOB）的地壳各向异性、莫霍深和Vp/Vs比。研究结果表明，秦岭造山带东部的 Vp/Vs 比值相对较低（1.74），地壳较薄。这表明，来自西藏中部的潜在地壳流可能不会对秦岭东麓的地壳变形产生重大影响。我们的研究结果表明，青藏南线、大巴山和青藏西线地区Vp/Vs比值高（∼1.75-1.88），地壳厚（∼44-56 km），地壳各向异性显著，延迟时间为0.22-0.86 s。QOB南部和大巴山地区地壳各向异性的快速方向为NW-SE，反映了与华北地块和华南地块碰撞有关的地壳构造走向。然而，在神农架-黄陵（SNHL）、汉南-米仓（HNMC）穹隆和江汉盆地下观察到较弱或可忽略的劈裂时间。地壳各向异性较弱可能与两个穹隆下的稳定基底有关，而江汉盆地下的劈裂时间可忽略不计可能与橄榄石或云母的α轴近乎垂直有关，这与俯冲的扬子地块板块断裂引起的俯冲地幔流有关。下伏岩浆在地壳下部聚集，形成岩浆岩下地壳，导致地壳Vp/Vs比值增大和地壳延伸。

{"title":"A study of crustal deformation beneath the Qinling Orogenic belt, Central China based on receiver function data","authors":"Ya Sun , Yangyi Deng , Syed-Muzyan Shahzad , Bo Chen","doi":"10.1016/j.jseaes.2024.106404","DOIUrl":"10.1016/j.jseaes.2024.106404","url":null,"abstract":"<div><div>A joint shear wave splitting technique based on receiver function data is employed to invert the crustal anisotropy, Moho depth, and Vp/Vs ratio in the Qinling Orogenic belt (QOB). Our findings reveal a relatively low Vp/Vs ratio (∼1.74) and a thin crust in east QOB. This suggests that potential crustal flow from central Tibet may not significantly influence the crustal deformation in east QOB. Our results demonstrate high Vp/Vs ratios (∼1.75–1.88), thick crust (∼44–56 km), and significant crustal anisotropy with a delay time of 0.22–0.86 s in south QOB, Dabashan, and west QOB regions. The fast directions of crustal anisotropy in the south QOB and Dabashan areas are NW-SE, which reflect the orientation of crustal fabrics associated with the collision between the North China Block and the South China Block. However, weak or negligible splitting times are observed beneath the Shennongjia-Huangling (SNHL), Hannan-Micang (HNMC) domes, and Jianghan Basin. The presence of weak crustal anisotropy is likely related to the stable basements beneath two domes, while the negligible splitting time beneath the Jianghan Basin might be attributed to the nearly vertical α-axis of olivines or mica associated with a subvertical mantle flow caused by slab break-off of the subducted Yangtze Block. The underlying magmas have gathered in the lower crust and formed the mafic lower crust, which cause an increase in the crust Vp/Vs ratio and crustal extension.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106404"},"PeriodicalIF":2.7,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Zircon and garnet U-Pb dating reveals the mineralization history of volcanic-related skarn iron deposits 锆石和石榴石 U-Pb 定年揭示了与火山有关的矽卡岩铁矿床的成矿史

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-09 DOI: 10.1016/j.jseaes.2024.106401

ZhiYuan Sun , MingLiang Wang , YongGang Sun , XiaoQiang Zhu , Tao Yang

The genesis of skarn garnet in volcanic-related skarn iron deposits is controversial because of the absent or ambiguous spatiotemporally related intrusions. In this study, we present combined LA-ICP-MS garnet U-Pb and SHRIMP zircon U-Pb ages to determine the spatiotemporal relationship between skarn garnet and a potentially related intrusion or causative volcanic rock. Three types of garnet (Grt1, Grt2, and Grt3) are identified in the Yamansu deposit, and Grt1 yields a lower intercept age of 326 ± 9 Ma (n = 32, MSWD = 0.3). SHRIMP zircon U-Pb dating of the associated volcanic rock yields a weighted mean age of 327 ± 3 Ma (n = 10, MSWD = 1.4), suggesting an isochronous relationship between the volcanic rock and Grt1. Grt2 and Grt3 yield lower intercept ages of 316 ± 6 Ma (n = 22, MSWD = 1.4) and 315 ± 6 Ma (n = 35, MSWD = 1.5), respectively. However, the zircon U-Pb weighted mean age of 252 ± 4 Ma (n = 5, MSWD = 0.8) obtained from the associated intrusion is obviously younger than the skarn age and the previously reported ore-forming age, implying no temporal relationship between mineralization and the intrusion. More significantly, precise ²⁰⁶Pb/²³⁸U weighted mean ages of 325 ± 9 Ma (n = 15, MSWD = 0.3), 316 ± 8 Ma (n = 11, MSWD = 0.4), and 319 ± 7 Ma (n = 12, MSWD = 0.5) were obtained from Grt1, Grt2, and Grt3, respectively, and we find that andradite-rich garnet with high U and ΣREE concentrations has the potential to yield the more precise U-Pb ages. The combined garnet and zircon U-Pb ages reveal that the hydrothermal skarn and mineralization in volcanic-related skarn iron deposits are related to volcanic activity rather than intrusions. Multiple episodes of volcanic-related hydrothermal activity may have caused multiple phases of skarn formation and mineralization in volcanic-related skarn iron deposits.

与火山有关的矽卡岩铁矿床中的矽卡岩石榴石的成因存在争议，因为不存在或模糊不清的时空相关侵入体。在这项研究中，我们结合LA-ICP-MS石榴石U-Pb年龄和SHRIMP锆石U-Pb年龄，确定了矽卡岩石榴石与可能相关的侵入体或成因火山岩之间的时空关系。在 Yamansu 矿床中发现了三种类型的石榴石（Grt1、Grt2 和 Grt3），Grt1 得到的较低截距年龄为 326 ± 9 Ma（n = 32，MSWD = 0.3）。对相关火山岩进行 SHRIMP 锆石 U-Pb 测定，得出的加权平均年龄为 327 ± 3 Ma（n = 10，MSWD = 1.4），表明火山岩与 Grt1 之间存在等时关系。Grt2和Grt3的截距年龄较低，分别为316 ± 6 Ma（n = 22，MSWD = 1.4）和315 ± 6 Ma（n = 35，MSWD = 1.5）。然而，从相关侵入体中获得的锆石 U-Pb 加权平均年龄为 252 ± 4 Ma（n = 5，MSWD = 0.8），明显比矽卡岩年龄和之前报告的成矿年龄年轻，这意味着成矿与侵入体之间没有时间关系。更重要的是，从Grt1、Grt2和Grt3获得的精确206Pb/238U加权平均年龄分别为325 ± 9 Ma（n = 15，MSWD = 0.3）、316 ± 8 Ma（n = 11，MSWD = 0.4）和319 ± 7 Ma（n = 12，MSWD = 0.5）。综合石榴石和锆石的 U-Pb 年龄显示，与火山有关的矽卡岩铁矿床中的热液矽卡岩和矿化与火山活动有关，而不是与侵入活动有关。与火山有关的多期热液活动可能导致了与火山有关的矽卡岩铁矿床中多个阶段的矽卡岩形成和矿化。

{"title":"Zircon and garnet U-Pb dating reveals the mineralization history of volcanic-related skarn iron deposits","authors":"ZhiYuan Sun , MingLiang Wang , YongGang Sun , XiaoQiang Zhu , Tao Yang","doi":"10.1016/j.jseaes.2024.106401","DOIUrl":"10.1016/j.jseaes.2024.106401","url":null,"abstract":"<div><div>The genesis of skarn garnet in volcanic-related skarn iron deposits is controversial because of the absent or ambiguous spatiotemporally related intrusions. In this study, we present combined LA-ICP-MS garnet U-Pb and SHRIMP zircon U-Pb ages to determine the spatiotemporal relationship between skarn garnet and a potentially related intrusion or causative volcanic rock. Three types of garnet (Grt1, Grt2, and Grt3) are identified in the Yamansu deposit, and Grt1 yields a lower intercept age of 326 ± 9 Ma (n = 32, MSWD = 0.3). SHRIMP zircon U-Pb dating of the associated volcanic rock yields a weighted mean age of 327 ± 3 Ma (n = 10, MSWD = 1.4), suggesting an isochronous relationship between the volcanic rock and Grt1. Grt2 and Grt3 yield lower intercept ages of 316 ± 6 Ma (n = 22, MSWD = 1.4) and 315 ± 6 Ma (n = 35, MSWD = 1.5), respectively. However, the zircon U-Pb weighted mean age of 252 ± 4 Ma (n = 5, MSWD = 0.8) obtained from the associated intrusion is obviously younger than the skarn age and the previously reported ore-forming age, implying no temporal relationship between mineralization and the intrusion. More significantly, precise <sup>206</sup>Pb/<sup>238</sup>U weighted mean ages of 325 ± 9 Ma (n = 15, MSWD = 0.3), 316 ± 8 Ma (n = 11, MSWD = 0.4), and 319 ± 7 Ma (n = 12, MSWD = 0.5) were obtained from Grt1, Grt2, and Grt3, respectively, and we find that andradite-rich garnet with high U and ΣREE concentrations has the potential to yield the more precise U-Pb ages. The combined garnet and zircon U-Pb ages reveal that the hydrothermal skarn and mineralization in volcanic-related skarn iron deposits are related to volcanic activity rather than intrusions. Multiple episodes of volcanic-related hydrothermal activity may have caused multiple phases of skarn formation and mineralization in volcanic-related skarn iron deposits.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106401"},"PeriodicalIF":2.7,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Rock-ice avalanche-generated erosion behaviors at the Sedongpu gully, Tibet, China: New insights from the geomorphologic perspective 中国西藏色季拉沟岩冰雪崩引发的侵蚀行为：地貌学视角的新见解

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-09 DOI: 10.1016/j.jseaes.2024.106403

Tiantian Zhang , Kai He , Bin Li , Yueping Yin , Haoyuan Gao , Shaohua Gao

In recent years, massive rock-ice avalanches frequently occur in the Sedongpu gully, forming an extensive dammed lake. Rock-ice avalanches not only threaten residents living in upstream and downstream areas, but also significantly change geomorphology. The gully geomorphology also experienced complicated alterations, due to distal motion distance and strong entrainment of debris flows, coming from the conversion of rock-ice avalanches. This study aims to determine the relation between dynamics erosion of rock-ice avalanches and geomorphology evolution during rock-ice avalanche events at the Sedongpu gully, where a large amount of moraine was distributed with five branch ditches. Field investigations, digital elevation models (DEMs), unmanned aerial vehicles (UAVs), multiphase remote-sensing images, topographic profiling, and InSAR monitoring are carried out to characterise the material changes, including composition, structure, transition, and deposits. Materials were entrained and scraped by debris flows and transported into the Yarlung Zangbo River. The total erosion volume of materials on the valley floor reached 980 million m³ from 2010 to 2021. Topographical profiling suggests that the most severe erosion also occurred in the midstream Sedongpu gully, with the maximum width of above 500 m. The overall elevation of the downstream valley increased by 50 m due to continuous deposits, and formed a large debris fans. The results might be helpful in further studies to reveal dynamic erosion geomorphology of rock-ice avalanches.

近年来，色东普沟经常发生大规模的岩冰崩塌，形成了一个大面积的堰塞湖。岩冰崩塌不仅威胁着上游和下游地区的居民，也极大地改变了地貌。由于岩冰崩塌转换产生的远距离运动和泥石流的强烈夹带，沟谷地貌也发生了复杂的变化。本研究旨在确定岩冰崩塌动态侵蚀与岩冰崩塌事件期间四洞铺沟谷地貌演变之间的关系，该沟谷分布着大量冰碛物和五条支沟。通过实地调查、数字高程模型（DEMs）、无人机（UAVs）、多相遥感图像、地形剖面和 InSAR 监测来描述物质变化的特征，包括成分、结构、过渡和沉积。物质被泥石流夹带和刮擦，并被输送到雅鲁藏布江。从 2010 年到 2021 年，谷底物质的侵蚀总量达到 9.8 亿立方米。地形剖面图显示，侵蚀最严重的地方也发生在中游的色东普沟，最大宽度超过 500 米，下游河谷的整体海拔因持续沉积而上升了 50 米，并形成了一个巨大的泥石流扇。这些结果可能有助于进一步研究揭示岩冰崩塌的动态侵蚀地貌。

{"title":"Rock-ice avalanche-generated erosion behaviors at the Sedongpu gully, Tibet, China: New insights from the geomorphologic perspective","authors":"Tiantian Zhang , Kai He , Bin Li , Yueping Yin , Haoyuan Gao , Shaohua Gao","doi":"10.1016/j.jseaes.2024.106403","DOIUrl":"10.1016/j.jseaes.2024.106403","url":null,"abstract":"<div><div>In recent years, massive rock-ice avalanches frequently occur in the Sedongpu gully, forming an extensive dammed lake. Rock-ice avalanches not only threaten residents living in upstream and downstream areas, but also significantly change geomorphology. The gully geomorphology also experienced complicated alterations, due to distal motion distance and strong entrainment of debris flows, coming from the conversion of rock-ice avalanches. This study aims to determine the relation between dynamics erosion of rock-ice avalanches and geomorphology evolution during rock-ice avalanche events at the Sedongpu gully, where a large amount of moraine was distributed with five branch ditches. Field investigations, digital elevation models (DEMs), unmanned aerial vehicles (UAVs), multiphase remote-sensing images, topographic profiling, and InSAR monitoring are carried out to characterise the material changes, including composition, structure, transition, and deposits. Materials were entrained and scraped by debris flows and transported into the Yarlung Zangbo River. The total erosion volume of materials on the valley floor reached 980 million m<sup>3</sup> from 2010 to 2021. Topographical profiling suggests that the most severe erosion also occurred in the midstream Sedongpu gully, with the maximum width of above 500 m. The overall elevation of the downstream valley increased by 50 m due to continuous deposits, and formed a large debris fans. The results might be helpful in further studies to reveal dynamic erosion geomorphology of rock-ice avalanches.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106403"},"PeriodicalIF":2.7,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Electrical architecture across the Ridge-Fault structure in the seismically active Jind-Rohtak-Delhi regions, NW India: Imaged from magnetotellurics studies 印度西北部地震活跃的 Jind-Rohtak-Delhi 地区山脊-断层结构的电结构：磁电研究成像

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-09 DOI: 10.1016/j.jseaes.2024.106407

Amit Kumar , C.K. Rao

The Delhi region is principally seismically active in the process of the India-Asia collision. Therefore, broadband Magnetotelluric (MT) studies were carried out at 11 stations along NW-SE profile passing through Jind-Rohtak regions. The rotation of the impedance tensor showed a regional strike angle of N8^oW, and phase tensor response approximate the 2-D structure. Therefore, electrical crustal structure was obtained from joint TE- and TM-modes data using a 2-D nonlinear conjugate gradient algorithm. The outcomes showed a ∼300 m thick sediments layer with conductivity ∼1 Ω-m beneath the entire profile, and conductor C2 revealed in the upper crust that joins the surface conductive layer. The conductors C1 and C3 are crustal features associated with Lahore-Delhi Ridge (LDR) and Delhi-Haridwar Ridge (DHR), respectively. The NNE-SSW trending Mahendragarh-Dehradun Fault (MDF) parallel to the DHR is suggested northwest dipping. The high conductivity supports the source of serpentine minerals in the lower crust. Our inference that the two ridges may be connected in the lower crust in the study region, and suggesting a triple junction. The fault zone tectonically associated with Himalayan arc, seismicity in the region occurs due to the movement of deep-seated heat in the process subduction. The surface conductive layer is attributed to Pleistocene age alluvium materials (silts and clays), and conductors are interpreted the partial melt or fluids that migrate upward through the pathway.

德里地区是印度-亚洲碰撞过程中主要的地震活跃地区。因此，我们在穿越 Jind-Rohtak 地区的 NW-SE 剖面上的 11 个台站进行了宽带磁测（MT）研究。阻抗张量的旋转显示了 N8oW 的区域走向角，相位张量响应近似于二维结构。因此，利用二维非线性共轭梯度算法，从 TE 和 TM 模式联合数据中获得了地壳电结构。结果表明，整个剖面下有厚度为 300 米的沉积层，其导电率为 1 Ω-m，在地壳上部发现了与地表导电层相连的导体 C2。导体 C1 和 C3 分别是与拉合尔-德里海脊（LDR）和德里-哈里瓦尔海脊（DHR）相关的地壳特征。与德里-哈里德瓦尔海脊平行的 NNE-SSW 走向的马亨德拉加尔-德勒敦断层（MDF）呈西北倾角。高电导率证明了下地壳中蛇纹石矿物的来源。我们推断，在研究区域的下地壳中，这两条山脊可能是相连的，并表明这是一个三重交界处。该断层带在构造上与喜马拉雅弧有关，该地区的地震发生是由于俯冲过程中深层热量的移动。表层导电层是更新世时期的冲积物（淤泥和粘土），导体被解释为部分熔体或流体通过路径向上迁移。

{"title":"Electrical architecture across the Ridge-Fault structure in the seismically active Jind-Rohtak-Delhi regions, NW India: Imaged from magnetotellurics studies","authors":"Amit Kumar , C.K. Rao","doi":"10.1016/j.jseaes.2024.106407","DOIUrl":"10.1016/j.jseaes.2024.106407","url":null,"abstract":"<div><div>The Delhi region is principally seismically active in the process of the India-Asia collision. Therefore, broadband Magnetotelluric (MT) studies were carried out at 11 stations along NW-SE profile passing through Jind-Rohtak regions. The rotation of the impedance tensor showed a regional strike angle of N8<sup>o</sup>W, and phase tensor response approximate the 2-D structure. Therefore, electrical crustal structure was obtained from joint TE- and TM-modes data using a 2-D nonlinear conjugate gradient algorithm. The outcomes showed a ∼300 m thick sediments layer with conductivity ∼1 Ω-m beneath the entire profile, and conductor C2 revealed in the upper crust that joins the surface conductive layer. The conductors C1 and C3 are crustal features associated with Lahore-Delhi Ridge (LDR) and Delhi-Haridwar Ridge (DHR), respectively. The NNE-SSW trending Mahendragarh-Dehradun Fault (MDF) parallel to the DHR is suggested northwest dipping. The high conductivity supports the source of serpentine minerals in the lower crust. Our inference that the two ridges may be connected in the lower crust in the study region, and suggesting a triple junction. The fault zone tectonically associated with Himalayan arc, seismicity in the region occurs due to the movement of deep-seated heat in the process subduction. The surface conductive layer is attributed to Pleistocene age alluvium materials (silts and clays), and conductors are interpreted the partial melt or fluids that migrate upward through the pathway.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106407"},"PeriodicalIF":2.7,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Petrological and geochronological constraints on the genesis of the Foping gneiss dome, South Qinling Belt, central China 中国中部南秦岭带佛坪片麻岩穹隆成因的岩石学和地质年代学约束

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-09 DOI: 10.1016/j.jseaes.2024.106406

Zhihui Liu , Longyao Chen , Xiaochun Liu , Bin Fu , Juan Hu , Guanggao Zheng

The Foping dome in the South Qinling Belt is a typical gneiss dome that records a multi-stage tectonic evolution from syn-collisional orogenesis to post-orogenic extension. We conducted a detailed petrological and geochronological investigation to constrain the genesis of the dome and its tectonic implications. Field occurrence, mineral assemblage, and metamorphic grade were used to divide the rocks of the Foping dome into three tectonic units. Conventional thermobarometry and pseudosection modelling were used to estimate the P-T conditions of the three units, yielding 640–680 °C and 3.4–5.0 kbar for the upper unit, 690–740 °C and 4.8–7.8 kbar for the middle unit, and 770–800 °C and 5.1–6.8 kbar for the lower unit, corresponding to amphibolite to granulite facies metamorphism under a geothermal gradient of ∼35 °C/km. The metamorphic patterns of three units reveal a metamorphic zonation characterized by decreasing metamorphic temperature from the centre to the periphery of the dome. Monazite SHRIMP U-Pb dating of metapelites yielded two major age clusters at 214–210 Ma and 207–197 Ma. The former cluster represents the timing of early regional progressive metamorphism induced by crustal thickening in a compressional setting, and the latter represents the timing of subsequent thermal metamorphism induced by magmatic diapirism in an extensional setting. The metamorphic zonation characteristics and ages of the Foping dome match with the pattern, nature, and ages of magmatism in this area, suggesting that the dome was formed by magmatic diapirism in a post-collisional extensional setting that was superimposed on the preceding progressive metamorphism associated with crustal thickening.

南秦岭地块中的佛坪穹窿是一个典型的片麻岩穹窿，记录了从同步碰撞成因到成因后延伸的多阶段构造演化过程。我们对该穹隆进行了详细的岩石学和地质年代调查，以确定其成因及其构造影响。我们利用野外发生、矿物组合和变质品位将佛坪穹隆的岩石划分为三个构造单元。利用传统的热压测量法和假吸力模型估算了三个单元的P-T条件，得出上单元的温度为640-680 °C，压力为3.4-5.0千巴；中单元的温度为690-740 °C，压力为4.8-7.8千巴；下单元的温度为770-800 °C，压力为5.1-6.8千巴。三个单元的变质形态显示了变质带的特征，即变质温度从圆顶中心向外围递减。元青石的 Monazite SHRIMP U-Pb 测定得出了两个主要年龄群，分别为 214-210 Ma 和 207-197 Ma。前一个年龄组代表了在压缩环境下由地壳增厚诱发的早期区域渐进变质作用的时间，而后一个年龄组代表了在伸展环境下由岩浆二叠作用诱发的后续热变质作用的时间。佛坪穹隆的变质分带特征和年龄与该地区岩浆活动的模式、性质和年龄相吻合，表明该穹隆是在碰撞后的伸展环境中由岩浆二期作用形成的，与之前与地壳增厚有关的渐进变质作用叠加在一起。

{"title":"Petrological and geochronological constraints on the genesis of the Foping gneiss dome, South Qinling Belt, central China","authors":"Zhihui Liu , Longyao Chen , Xiaochun Liu , Bin Fu , Juan Hu , Guanggao Zheng","doi":"10.1016/j.jseaes.2024.106406","DOIUrl":"10.1016/j.jseaes.2024.106406","url":null,"abstract":"<div><div>The Foping dome in the South Qinling Belt is a typical gneiss dome that records a multi-stage tectonic evolution from <em>syn</em>-collisional orogenesis to post-orogenic extension. We conducted a detailed petrological and geochronological investigation to constrain the genesis of the dome and its tectonic implications. Field occurrence, mineral assemblage, and metamorphic grade were used to divide the rocks of the Foping dome into three tectonic units. Conventional thermobarometry and pseudosection modelling were used to estimate the P-T conditions of the three units, yielding 640–680 °C and 3.4–5.0 kbar for the upper unit, 690–740 °C and 4.8–7.8 kbar for the middle unit, and 770–800 °C and 5.1–6.8 kbar for the lower unit, corresponding to amphibolite to granulite facies metamorphism under a geothermal gradient of ∼35 °C/km. The metamorphic patterns of three units reveal a metamorphic zonation characterized by decreasing metamorphic temperature from the centre to the periphery of the dome. Monazite SHRIMP U-Pb dating of metapelites yielded two major age clusters at 214–210 Ma and 207–197 Ma. The former cluster represents the timing of early regional progressive metamorphism induced by crustal thickening in a compressional setting, and the latter represents the timing of subsequent thermal metamorphism induced by magmatic diapirism in an extensional setting. The metamorphic zonation characteristics and ages of the Foping dome match with the pattern, nature, and ages of magmatism in this area, suggesting that the dome was formed by magmatic diapirism in a post-collisional extensional setting that was superimposed on the preceding progressive metamorphism associated with crustal thickening.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106406"},"PeriodicalIF":2.7,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Abundance and origin of helium in the Lower Paleozoic gas: A case study from the Daniudi field of the Ordos Basin, central China 下古生代气体中氦的丰度和来源：中国中部鄂尔多斯盆地大牛地气田案例研究

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-09 DOI: 10.1016/j.jseaes.2024.106405

Xiaoqi Wu , Quanyou Liu , Chunhua Ni , Ping Wang , Dongya Zhu , Huichong Jia

Natural gas from ancient strata in sedimentary basins tends to be enriched with helium (He). Lower Paleozoic gas in the Daniudi field (DNDF) of the Ordos Basin in central China provides a good case study to reveal He generation and accumulation mechanisms in deep strata. Understanding He accumulation in the Daniudi field is crucial because the increasing global demand for He requires the identification of new sources in existing natural gas reservoirs. Here, the geochemical characteristics of Lower Paleozoic gas from the DNDF are investigated, aiming to reveal the concentration, origin, and controlling factors of He accumulation. Natural gas in Lower Ordovician Majiagou Formation (O₁m) reservoirs is He-depleted (0.0126 %–0.0187 %, mean 0.0153 %). The ³He/⁴He and corresponding R/Ra ratios range from 3.12 to 3.95 × 10⁻⁸ and 0.022 to 0.028, respectively, indicative of a crustal origin of He. The He concentration was diluted by alkane gases, as indicated by a negative correlation between He content and the CH₄ content, as well as the dryness coefficient; however, it was not affected by the degree of thermal maturity or the type of organic matter in the source rocks, as indicated by a lack of correlation between He content and the carbon isotopic ratios of CH₄ and C₂H₆. The N₂/He ratio of O₁m gas is generally in a range from 1.14 to 7.65, which is markedly lower than the ratio (19–50) in natural gas with He commercial production value (He% ≥ 0.1 %). The He content in O₁m gas is negatively correlated with the content of total dissolved solids (TDS) in formation water; the low He content may be attributable to the high TDS content. The pressure in Paleozoic strata of the DNDF has decreased since the Late Cretaceous due to continuous regional uplift, resulting in decreased He solubility in the formation water and the exsolution of previously dissolved He into gas pools.

沉积盆地古地层中的天然气往往富含氦（He）。中国中部鄂尔多斯盆地大牛地气田（DNDF）的下古生界天然气为揭示深地层中 He 的生成和累积机制提供了一个很好的案例研究。了解大牛地气田的 He 累积至关重要，因为全球对 He 的需求日益增长，需要在现有天然气储层中寻找新的来源。本文研究了达尼乌迪气田下古生界天然气的地球化学特征，旨在揭示 He 累积的浓度、来源和控制因素。下奥陶统马家沟组（O1m）储层中的天然气是贫氦（0.0126%-0.0187%，平均0.0153%）。3He/4He和相应的R/Ra比值分别为3.12-3.95×10-8和0.022-0.028，表明He来源于地壳。He 浓度受到烷烃气体的稀释，这一点从 He 含量与 CH4 含量以及干燥系数之间的负相关关系可以看出；但是，源岩的热成熟度或有机物类型对 He 浓度没有影响，这一点从 He 含量与 CH4 和 C2H6 的碳同位素比值之间缺乏相关性可以看出。O1m 天然气的 N2/He 比率一般在 1.14 至 7.65 之间，明显低于具有 He 商业生产价值的天然气中的比率（19-50）（He% ≥ 0.1%）。O1m 天然气中的 He 含量与地层水中的总溶解固体（TDS）含量呈负相关；He 含量低可能与 TDS 含量高有关。自晚白垩世以来，由于区域持续隆起，DNDF 古生代地层中的压力下降，导致地层水中的 He 溶解度降低，以前溶解的 He 溶出到气池中。

{"title":"Abundance and origin of helium in the Lower Paleozoic gas: A case study from the Daniudi field of the Ordos Basin, central China","authors":"Xiaoqi Wu , Quanyou Liu , Chunhua Ni , Ping Wang , Dongya Zhu , Huichong Jia","doi":"10.1016/j.jseaes.2024.106405","DOIUrl":"10.1016/j.jseaes.2024.106405","url":null,"abstract":"<div><div>Natural gas from ancient strata in sedimentary basins tends to be enriched with helium (He). Lower Paleozoic gas in the Daniudi field (DNDF) of the Ordos Basin in central China provides a good case study to reveal He generation and accumulation mechanisms in deep strata. Understanding He accumulation in the Daniudi field is crucial because the increasing global demand for He requires the identification of new sources in existing natural gas reservoirs. Here, the geochemical characteristics of Lower Paleozoic gas from the DNDF are investigated, aiming to reveal the concentration, origin, and controlling factors of He accumulation. Natural gas in Lower Ordovician Majiagou Formation (O<sub>1</sub>m) reservoirs is He-depleted (0.0126 %–0.0187 %, mean 0.0153 %). The <sup>3</sup>He/<sup>4</sup>He and corresponding R/Ra ratios range from 3.12 to 3.95 × 10<sup>−8</sup> and 0.022 to 0.028, respectively, indicative of a crustal origin of He. The He concentration was diluted by alkane gases, as indicated by a negative correlation between He content and the CH<sub>4</sub> content, as well as the dryness coefficient; however, it was not affected by the degree of thermal maturity or the type of organic matter in the source rocks, as indicated by a lack of correlation between He content and the carbon isotopic ratios of CH<sub>4</sub> and C<sub>2</sub>H<sub>6</sub>. The N<sub>2</sub>/He ratio of O<sub>1</sub>m gas is generally in a range from 1.14 to 7.65, which is markedly lower than the ratio (19–50) in natural gas with He commercial production value (He% ≥ 0.1 %). The He content in O<sub>1</sub>m gas is negatively correlated with the content of total dissolved solids (TDS) in formation water; the low He content may be attributable to the high TDS content. The pressure in Paleozoic strata of the DNDF has decreased since the Late Cretaceous due to continuous regional uplift, resulting in decreased He solubility in the formation water and the exsolution of previously dissolved He into gas pools.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106405"},"PeriodicalIF":2.7,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Spatiotemporal variations of non-seismically fatal landslides in Northwest China: A case study from Shaanxi province 中国西北地区非地震致灾滑坡的时空变化：陕西省案例研究

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-07 DOI: 10.1016/j.jseaes.2024.106389

Baoqin Lian , Jianbing Peng , Qiangbing Huang , Jiading Wang , Xingang Wang , Sheng Hu , Kai Liu

Landslides are one of the devastating geo-hazards that result in severe casualties in Northwest China (NW China) every year. However, a comprehensive landslide database is yet to be available for quantitatively assessing the distribution of fatal landslides in NW China. To investigate the spatiotemporal characteristics of non-seismically fatal landslides in NW China, we carried out a study using fatal landslides that occurred in Shaanxi province as an example to construct a new database by incorporating data of fatal landslides that occurred in the period between 1996 and 2018. A total of 332 non-seismically fatal landslides that claimed 1132 lives were compiled in this database. Additionally, a thorough study of spatial and temporal variations of fatal landslides reveals that anthropogenic landslides occur approximately evenly throughout the year. Natural fatal landslides, however, rise noticeably in July, August, and September. The spatial distribution analysis showed that fatal landslides in Shaanxi province of China were mainly distributed in the An’ kang, Yan’an, and Shangluo regions. Additionally, areas with relatively high relief (46.1 to 123 m), steep–slope topography (19.2 to 26.1°), and intense precipitation (465 to 937 mm) are more vulnerable to naturally-triggered landslides. The spatiotemporal analysis of the fatal landslides revealed increasing trends in zones such as Yan’an and Yulin cities (in northern part), and in An’kang city (in southern part). When combined with other information, the Fatal Landslide Database of Shaanxi Province can be used to provide a guide for risk assessment and spatial planning studies to mitigate geo-hazard risks.

滑坡是破坏性地质灾害之一，每年都会在中国西北地区造成严重的人员伤亡。然而，目前还没有一个全面的滑坡数据库来定量评估中国西北地区致命滑坡的分布情况。为了研究中国西北地区非地震致灾滑坡的时空特征，我们以陕西省发生的致灾滑坡为例开展了一项研究，通过纳入 1996 年至 2018 年期间发生的致灾滑坡数据，构建了一个新的数据库。该数据库共收录了 332 起非地震致死滑坡事故，造成 1132 人死亡。此外，对致命滑坡的空间和时间变化的深入研究表明，人为滑坡在一年中大致平均发生。然而，在七月、八月和九月，致命的自然滑坡事故明显增多。空间分布分析表明，中国陕西省的致命滑坡主要分布在安康、延安和商洛地区。此外，地势相对较高（46.1 至 123 米）、地形坡度较陡（19.2 至 26.1°）、降水量较大（465 至 937 毫米）的地区更容易发生自然引发的滑坡。对致命滑坡的时空分析表明，北部的延安市和榆林市以及南部的安康市等地区的致命滑坡呈上升趋势。结合其他信息，陕西省致命滑坡数据库可为风险评估和空间规划研究提供指导，以减轻地质灾害风险。

{"title":"Spatiotemporal variations of non-seismically fatal landslides in Northwest China: A case study from Shaanxi province","authors":"Baoqin Lian , Jianbing Peng , Qiangbing Huang , Jiading Wang , Xingang Wang , Sheng Hu , Kai Liu","doi":"10.1016/j.jseaes.2024.106389","DOIUrl":"10.1016/j.jseaes.2024.106389","url":null,"abstract":"<div><div>Landslides are one of the devastating geo-hazards that result in severe casualties in Northwest China (NW China) every year. However, a comprehensive landslide database is yet to be available for quantitatively assessing the distribution of fatal landslides in NW China. To investigate the spatiotemporal characteristics of non-seismically fatal landslides in NW China, we carried out a study using fatal landslides that occurred in Shaanxi province as an example to construct a new database by incorporating data of fatal landslides that occurred in the period between 1996 and 2018. A total of 332 non-seismically fatal landslides that claimed 1132 lives were compiled in this database. Additionally, a thorough study of spatial and temporal variations of fatal landslides reveals that anthropogenic landslides occur approximately evenly throughout the year. Natural fatal landslides, however, rise noticeably in July, August, and September. The spatial distribution analysis showed that fatal landslides in Shaanxi province of China were mainly distributed in the An’ kang, Yan’an, and Shangluo regions. Additionally, areas with relatively high relief (46.1 to 123 m), steep–slope topography (19.2 to 26.1°), and intense precipitation (465 to 937 mm) are more vulnerable to naturally-triggered landslides. The spatiotemporal analysis of the fatal landslides revealed increasing trends in zones such as Yan’an and Yulin cities (in northern part), and in An’kang city (in southern part). When combined with other information, the Fatal Landslide Database of Shaanxi Province can be used to provide a guide for risk assessment and spatial planning studies to mitigate geo-hazard risks.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106389"},"PeriodicalIF":2.7,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Silician zoning of magnetite in a Fe skarn deposit: A potential low-temperature indicator in magmatic-hydrothermal systems? 铁矽卡岩矿床中磁铁矿的矽卡岩分带：岩浆-热液系统中的潜在低温指标？

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-07 DOI: 10.1016/j.jseaes.2024.106402

Wanyi Feng, Jiahao Zheng

Single magnetite crystals from the Cihai Fe skarn deposit in Northwestern China are strongly growth zoned. Magnetite cores are in equilibrium with garnet whereas magnetite rims are enclosed by calcite. The chemical zoning in magnetite is well defined by an abrupt core-to-rim Si and Ca increase as well as Ti decrease. Electron microprobe analysis (EMPA) results show that magnetites rims contain from 2.24 to 5.70 wt% SiO₂ (averaging 4.56 wt%), which are silician magnetite. Plots of EMPA data suggest that silician magnetite in the Cihai skarn deposit presents in the form of [Si⁴⁺]^IV + [Fe²⁺]^VI ↔ [Fe³⁺]^IV + [Fe³⁺]^VI. The LA-ICP-MS dating results show that the garnet coexisting with the magnetite core has a U-Pb age of 282.5 ± 2.6 Ma, which is consistent with the timing of Fe mineralization in the retrograde skarn stage, indicating that silician magnetite was formed within a relatively short time interval after magnetite precipitation. Based on coexisting minerals, chemical compositions, and our previous fluid inclusion analyses, we propose that the Si zoning of magnetite is largely temperature dependent and, thus, is interpreted as a retrograde growth zoning. It is suggested that silician magnetite formed as a result of changing compatibility due to decreasing temperatures and can potentially be used to trace ore-forming temperatures in hydrothermal deposits. Our study provides independent constraints on the conditions of hydrothermal magnetite formation in the Cihai Fe skarn deposit, and suggests that silician magnetite may serve as a potential relatively low-temperature (<300 °C) indicator in other less-well-constrained magmatic-hydrothermal systems.

来自中国西北部慈海铁矽卡岩矿床的磁铁矿单晶体具有强烈的生长分带。磁铁矿核心与石榴石处于平衡状态，而磁铁矿边缘则被方解石包围。磁铁矿的化学分带非常明确，从岩心到岩缘，Si 和 Ca 突然增加，Ti 突然减少。电子微探针分析（EMPA）结果表明，磁铁矿边缘含有 2.24 至 5.70 wt% 的 SiO2（平均为 4.56 wt%），属于硅质磁铁矿。EMPA 数据图表明，慈海矽卡岩矿床中的硅质磁铁矿以 [Si4+]IV + [Fe2+]VI ↔ [Fe3+]IV + [Fe3+]VI 的形式存在。LA-ICP-MS 测定结果显示，与磁铁矿核共生的石榴石的 U-Pb 年龄为 282.5 ± 2.6 Ma，与逆行矽卡岩阶段的铁矿化时间一致，表明硅质磁铁矿是在磁铁矿沉淀后较短时间内形成的。根据共生矿物、化学成分以及之前的流体包裹体分析，我们提出磁铁矿的硅分带主要取决于温度，因此可解释为逆行生长分带。我们认为硅质磁铁矿是由于温度降低导致相容性发生变化而形成的，因此有可能用来追踪热液矿床中的成矿温度。我们的研究为慈海铁矽卡岩矿床中热液磁铁矿的形成条件提供了独立的约束条件，并表明硅质磁铁矿可作为其他条件限制较少的岩浆-热液系统中潜在的相对低温（<300 °C）指示剂。

{"title":"Silician zoning of magnetite in a Fe skarn deposit: A potential low-temperature indicator in magmatic-hydrothermal systems?","authors":"Wanyi Feng, Jiahao Zheng","doi":"10.1016/j.jseaes.2024.106402","DOIUrl":"10.1016/j.jseaes.2024.106402","url":null,"abstract":"<div><div>Single magnetite crystals from the Cihai Fe skarn deposit in Northwestern China are strongly growth zoned. Magnetite cores are in equilibrium with garnet whereas magnetite rims are enclosed by calcite. The chemical zoning in magnetite is well defined by an abrupt core-to-rim Si and Ca increase as well as Ti decrease. Electron microprobe analysis (EMPA) results show that magnetites rims contain from 2.24 to 5.70 wt% SiO<sub>2</sub> (averaging 4.56 wt%), which are silician magnetite. Plots of EMPA data suggest that silician magnetite in the Cihai skarn deposit presents in the form of [Si<sup>4+</sup>]<sup>IV</sup> + [Fe<sup>2+</sup>]<sup>VI</sup> ↔ [Fe<sup>3+</sup>]<sup>IV</sup> + [Fe<sup>3+</sup>]<sup>VI</sup>. The LA-ICP-MS dating results show that the garnet coexisting with the magnetite core has a U-Pb age of 282.5 ± 2.6 Ma, which is consistent with the timing of Fe mineralization in the retrograde skarn stage, indicating that silician magnetite was formed within a relatively short time interval after magnetite precipitation. Based on coexisting minerals, chemical compositions, and our previous fluid inclusion analyses, we propose that the Si zoning of magnetite is largely temperature dependent and, thus, is interpreted as a retrograde growth zoning. It is suggested that silician magnetite formed as a result of changing compatibility due to decreasing temperatures and can potentially be used to trace ore-forming temperatures in hydrothermal deposits. Our study provides independent constraints on the conditions of hydrothermal magnetite formation in the Cihai Fe skarn deposit, and suggests that silician magnetite may serve as a potential relatively low-temperature (<300 °C) indicator in other less-well-constrained magmatic-hydrothermal systems.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106402"},"PeriodicalIF":2.7,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Middle-Late Permian Yakshawa and Late Cretaceous Daresard bauxite deposits, western Iran: Elemental deportment, parental affinities and genesis of REY minerals 伊朗西部中-晚二叠世雅克沙瓦和晚白垩世达雷萨德铝土矿床：REY 矿物的元素分类、亲缘关系和成因

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-05 DOI: 10.1016/j.jseaes.2024.106397

Farhad Ahmadnejad , Giovanni Mongelli , Havzhin Parkalian , Hadis Haghighi , Mohammad Sharifi

The Middle-Late Permian Yakshawa bauxite deposit in the Sanandaj-Sirjan Zone and the Late Cretaceous Daresard bauxite deposit in the Zagros Fold-Thrust Belt have bauxite ores with different textures and mineralogical compositions. The presence of detrital and authigenic REY-phosphates, fluorocarbonates of the bastnasite group, and cerianite with diverse generations reflect an intricate formation process of the REY-bearing minerals in these two deposits. This clearly shows that the studied deposits have a multi-stage evolution including diagenetic and/or low-grade metamorphic, in situ fluid-assisted dissolution–reprecipitation reactions, and later bauxitization. The high abundance of monazite, textural relationships, and its LREE pattern indicate this mineral is the main LREE reservoir in the studied bauxite ores whereas xenotime, both authigenic and detrital, is the main host for HREE. The R-mode factor analyses indicates that the bauxitization process induces, at large, similar interelemental relationships in the studied deposits involving the attitude of Al oxyhydroxides, Ti oxides, and Fe oxyhydroxides to concentrate critical metals and the capability of REY-phosphate of being the main reservoir of REE + Y. As for provenance, the Eu/Eu*, Sm/Nd, and Nb/Ta proxies suggest that the bauxite ores of the Yakshawa deposit have a genetic relationship with Middle-Late Permian mafic volcanic rocks, whereas the ores of the Daresard deposit show parental affinity with the underlying fine-grained clayey limestone of the Sarvak Formation.

位于萨南达吉-锡尔詹地带的中-晚二叠世雅克沙瓦铝土矿床和位于扎格罗斯褶皱-推覆带的晚白垩世达雷萨德铝土矿床的铝土矿具有不同的质地和矿物成分。在这两个矿床中，存在不同世代的脱落和自生REY磷酸盐、姥钠石类氟碳酸盐和铈镧矿，反映了含REY矿物的复杂形成过程。这清楚地表明，所研究的矿床经历了多阶段演化，包括成岩和/或低级变质、原地流体辅助溶解-重沉淀反应以及后期铝土化。独居石的高丰度、纹理关系及其 LREE 模式表明，在所研究的铝土矿中，独居石是主要的 LREE 储层，而自生和非自生的氙则是 HREE 的主要矿床。R 模式因子分析表明，在所研究的矿床中，铝土矿化过程在很大程度上引起了类似的元素间关系，包括 Al 氧氢氧化物、Ti 氧化物和 Fe 氧氢氧化物浓缩关键金属的态度，以及 REY 磷酸盐作为 REE + Y 主要储层的能力。至于产地，Eu/Eu*、Sm/Nd 和 Nb/Ta 代用指标表明，Yakshawa 矿床的铝土矿石与中-晚二叠世岩浆火山岩有遗传关系，而 Daresard 矿床的矿石则与 Sarvak 地层下的细粒粘土灰岩有亲缘关系。

{"title":"The Middle-Late Permian Yakshawa and Late Cretaceous Daresard bauxite deposits, western Iran: Elemental deportment, parental affinities and genesis of REY minerals","authors":"Farhad Ahmadnejad , Giovanni Mongelli , Havzhin Parkalian , Hadis Haghighi , Mohammad Sharifi","doi":"10.1016/j.jseaes.2024.106397","DOIUrl":"10.1016/j.jseaes.2024.106397","url":null,"abstract":"<div><div>The Middle-Late Permian Yakshawa bauxite deposit in the Sanandaj-Sirjan Zone and the Late Cretaceous Daresard bauxite deposit in the Zagros Fold-Thrust Belt have bauxite ores with different textures and mineralogical compositions. The presence of detrital and authigenic REY-phosphates, fluorocarbonates of the bastnasite group, and cerianite with diverse generations reflect an intricate formation process of the REY-bearing minerals in these two deposits. This clearly shows that the studied deposits have a multi-stage evolution including diagenetic and/or low-grade metamorphic, in situ fluid-assisted dissolution–reprecipitation reactions, and later bauxitization. The high abundance of monazite, textural relationships, and its LREE pattern indicate this mineral is the main LREE reservoir in the studied bauxite ores whereas xenotime, both authigenic and detrital, is the main host for HREE. The R-mode factor analyses indicates that the bauxitization process induces, at large, similar interelemental relationships in the studied deposits involving the attitude of Al oxyhydroxides, Ti oxides, and Fe oxyhydroxides to concentrate critical metals and the capability of REY-phosphate of being the main reservoir of REE + Y. As for provenance, the Eu/Eu*, Sm/Nd, and Nb/Ta proxies suggest that the bauxite ores of the Yakshawa deposit have a genetic relationship with Middle-Late Permian mafic volcanic rocks, whereas the ores of the Daresard deposit show parental affinity with the underlying fine-grained clayey limestone of the Sarvak Formation.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106397"},"PeriodicalIF":2.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Petrogenesis of U-rich two-mica granite from the Mesozoic Reshui pluton (Nanling Range, South China) with implications for uranium mineralization 中生代雷水岩体（华南南岭）富铀双云母花岗岩的岩石成因及其对铀矿化的影响

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-11-04 DOI: 10.1016/j.jseaes.2024.106400

Jihua Tao , Yuegui Yang , Xianyuan Su , Chengbiao Leng , Kaixuan Li , Xilian Chen , Zhitian Xu

Muscovite-bearing granites are the dominant rock type associated with metallic deposits in South China. Some of these granites are rich in U and considered potential sources for subsequent hydrothermal uranium mineralization. Although widely studied, the petrogenesis of muscovite-bearing granites remains obscure. The Reshui pluton contains fine-grained biotite granite and coarse grained two-mica granite (CGTG). CGTG exhibits high U concentrations (5.07–40.15 ppm, average 15.94 ppm) and is typical of U-rich granite in South China. We conducted detailed petrographic, geochemical and biotite mineralogical analyses of the CGTG from the Reshui pluton. Our findings provide new insights into the petrogenesis of U-rich granites in South China and their significance for uranium mineralization. LA-ICP-MS zircon U–Pb dating shows that the CGTG were formed at 167.3 ± 1.7 Ma. Integrated petrological, whole-rock geochemical and biotite geochemical data, the negative and limited variation of the ε_Nd(t) values (from − 10.8 to − 9.6) and a two-stage Paleoproterozoic model age (1.72 to 1.83 Ga), suggest the U-rich S-type CGTG formed by partial melting of Paleoproterozoic clay-rich pelitic rocks and underwent extensive fractional crystallization. The U-rich pelitic magma sources characterized by relatively low oxygen fugacity and temperature, relatively high degree of magmatic differentiation and F content are the main factors controlling U enrichment in the Reshui pluton CGTG. The petrologic and whole-rock geochemical characteristics, together with the biotite chemical compositions and disseminated U-rich accessory minerals including uraninite, indicate that the CGTG in the Reshui pluton has a high uranium mineralization potential and should be given more attention in further explorations.

含熔岩的花岗岩是华南金属矿床的主要岩石类型。其中一些花岗岩富含铀，被认为是后续热液铀矿化的潜在来源。尽管对含麝香石花岗岩的岩石成因进行了广泛的研究，但其成因仍然模糊不清。丽水岩体包含细粒生物花岗岩和粗粒双云母花岗岩（CGTG）。粗粒双云母花岗岩的铀含量较高（5.07-40.15 ppm，平均 15.94 ppm），是华南地区典型的富铀花岗岩。我们对来自Reshui岩体的CGTG进行了详细的岩石学、地球化学和生物矿物学分析。我们的研究结果为了解华南地区富铀花岗岩的岩石成因及其对铀矿化的意义提供了新的视角。LA-ICP-MS锆石U-Pb年代测定显示，CGTG形成于167.3 ± 1.7 Ma。综合岩石学、全岩地球化学和生物岩石地球化学数据、εNd(t)值的负向有限变化（从-10.8到-9.6）和两段古近纪模型年龄（1.72到1.83 Ga），表明富铀S型CGTG是由古近纪富粘土质球粒岩部分熔融形成，并经历了广泛的分块结晶过程。富含铀的球粒岩岩浆源具有相对较低的氧富集度和温度、相对较高的岩浆分异程度和萤石含量等特征，是控制瑞水岩柱CGTG中铀富集的主要因素。岩石学和全岩地球化学特征，以及生物岩化学成分和包括铀矿石在内的富铀伴生矿物的赋存，都表明了瑞水系块体CGTG具有很高的铀成矿潜力，在进一步勘探中应给予更多的关注。

{"title":"Petrogenesis of U-rich two-mica granite from the Mesozoic Reshui pluton (Nanling Range, South China) with implications for uranium mineralization","authors":"Jihua Tao , Yuegui Yang , Xianyuan Su , Chengbiao Leng , Kaixuan Li , Xilian Chen , Zhitian Xu","doi":"10.1016/j.jseaes.2024.106400","DOIUrl":"10.1016/j.jseaes.2024.106400","url":null,"abstract":"<div><div>Muscovite-bearing granites are the dominant rock type associated with metallic deposits in South China. Some of these granites are rich in U and considered potential sources for subsequent hydrothermal uranium mineralization. Although widely studied, the petrogenesis of muscovite-bearing granites remains obscure. The Reshui pluton contains fine-grained biotite granite and coarse grained two-mica granite (CGTG). CGTG exhibits high U concentrations (5.07–40.15 ppm, average 15.94 ppm) and is typical of U-rich granite in South China. We conducted detailed petrographic, geochemical and biotite mineralogical analyses of the CGTG from the Reshui pluton. Our findings provide new insights into the petrogenesis of U-rich granites in South China and their significance for uranium mineralization. LA-ICP-MS zircon U–Pb dating shows that the CGTG were formed at 167.3 ± 1.7 Ma. Integrated petrological, whole-rock geochemical and biotite geochemical data, the negative and limited variation of the ε<sub>Nd</sub>(t) values (from − 10.8 to − 9.6) and a two-stage Paleoproterozoic model age (1.72 to 1.83 Ga), suggest the U-rich S-type CGTG formed by partial melting of Paleoproterozoic clay-rich pelitic rocks and underwent extensive fractional crystallization. The U-rich pelitic magma sources characterized by relatively low oxygen fugacity and temperature, relatively high degree of magmatic differentiation and F content are the main factors controlling U enrichment in the Reshui pluton CGTG. The petrologic and whole-rock geochemical characteristics, together with the biotite chemical compositions and disseminated U-rich accessory minerals including uraninite, indicate that the CGTG in the Reshui pluton has a high uranium mineralization potential and should be given more attention in further explorations.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106400"},"PeriodicalIF":2.7,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0