Journal of Asian Earth Sciences最新文献_第6页

Late Triassic ore-forming adakitic porphyries from post-collisional lithospheric extension in the eastern Kunlun Orogen, northern Tibet 藏北东昆仑造山带碰撞后岩石圈伸展中的晚三叠世艾达质斑岩成矿

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-19 DOI: 10.1016/j.jseaes.2025.106922

Jinyang Zhang , Zhongyuan Ma , Yong Zhang , Jianxun Yuan , Jiaxing Chai , Lanxin Zhang , Changqian Ma , Jianwei Li , Yuanming Pan

Post-collisional porphyry Cu systems are commonly associated with adakitic intrusions and lithospheric extension. In this study, Wulanwuzhu’er porphyritic diorites and Yazigou dolerites have been investigated to support Late Triassic adakitic rocks for porphyry Cu systems of the eastern Kunlun Orogen formed in post-collisional lithospheric extension. The porphyritic diorites emplaced as dykes at 211–214 Ma are ‌spatiotemporally and genetically related to the epithermal Ag-Pb-Zn mineralization. The diorites contain high Al₂O₃ hornblende (up to 13.74 wt%) and belong to metaluminous and high-K calc-alkaline series with moderately high Sr/Y values and enriched Nd isotopes. They were most likely derived from a moderately oxidized metasomatic lithosphere mantle under a post-collisional setting, with adakitic signatures caused by hornblende crystallization at the lower crust. The dolerite dykes (222 ± 1.3 Ma) are metaluminous and calc-alkaline with high Mg#, Ni (up to 103 ppm), and ε_Nd(t) values (up to 6.1). They were originated from a depleted mantle in the spinel stability field with small melting degrees, supporting a significant upwelling of the asthenosphere to induce the post-collisional lithospheric extension. Systematic compilation of regional geochemical data in the orogen suggests that Late Triassic adakitic intrusions in the eastern section have higher MgO and Ni contents and oxygen fugacities than the counterparts in the western section, probably indicating a slab tearing model. Vigorous lower crustal magmatic processes in a thickened continental crust, the post-collisional slab tearing, and oxidized sources of metasomatic mantle or subducted slab for the eastern Kunlun Orogen are favorable for porphyry Cu mineralization.

碰撞后斑岩型铜体系通常与埃达质侵入和岩石圈伸展有关。本文研究了东昆仑造山带碰撞后岩石圈伸展形成的斑岩-铜体系中，乌兰五柱二斑岩闪长岩和雅兹沟斑岩支持晚三叠世埃达质岩。在211 ~ 214 Ma成脉侵位的斑岩闪长岩在时空和成因上与浅成热液银铅锌成矿作用有关。闪长岩含高Al2O3角闪石（重达13.74 wt%），属铝质、高钾钙碱性系列，Sr/Y值中等，Nd同位素富集。它们很可能来自于碰撞后环境下的中度氧化交代岩石圈地幔，具有下地壳角闪石结晶引起的绿质特征。白云岩岩脉（222±1.3 Ma）具有高Mg#、高Ni（可达103 ppm）、高εNd(t)值（可达6.1）的铝质钙碱性。它们起源于尖晶石稳定场的枯竭地幔，熔融程度小，支持软流圈的明显上升流，诱发碰撞后岩石圈扩张。对造山带区域地球化学资料的系统整理表明，东段晚三叠世埃达质岩体的MgO、Ni含量和氧逸度均高于西段的同类岩体，可能具有板块撕裂模式。东昆仑造山带加厚大陆地壳中剧烈的下地壳岩浆作用、碰撞后的板块撕裂作用以及交代地幔或俯冲板块的氧化源均有利于斑岩型铜成矿。

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引用次数: 0

The Sarma segment of the Akitkan orogenic Belt, Siberian craton: Milestones of the Archean-Proterozoic history 西伯利亚克拉通阿基特坎造山带萨尔马段：太古宙-元古宙历史的里程碑

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-19 DOI: 10.1016/j.jseaes.2025.106923

Uliana S. Efremova, Tatiana V. Donskaya, Dmitrii P. Gladkochub, Anatolii M. Mazukabzov, Elena I. Demonterova, Alexei V. Ivanov, Nikolay V. Bryansky

New constraints on local geology, geochemistry, and geochronology (LA-ICP-MS U-Pb detrital zircon ages) have been obtained for metamorphic clastic rocks assigned previously to the Khargitui Formation, presumably the oldest clastic rocks in the Sarma segment of the Akitkan orogenic belt in the southern Siberian craton. The new data reveal three units of rocks formed at different stages of the Akitkan orogen evolution. Unit 1 includes mainly leucocratic gneisses derived from 2.7–2.5 Ga polymictic sandstones or graywackes. These sediments were deposited upon the basement of the Sarma terrane composed of 2.88 Ga TTG granitoids that became the source of clastic material. Unit 2 consists of quartzite and schists produced by metamorphism of quartz and polymictic sandstones and siltstones. Judging by the ages of detrital zircons from mica-quartz schists, along with the age of metamorphism, the deposition of the sedimentary protoliths lasted from 2.15 to 1.95 Ga. It was maintained by destruction of felsic rocks within the Sarma terrane prior to the collisional event that led to the formation of the Akitkan orogen. Unit 3 likewise includes quartzites and schists but those derived from more mature sediments. The clastic material predominantly originated from 1.88–1.84 Ga rocks of the South Siberian magmatic belt and was deposited in intracontinental basins between 1.00 and 0.72 Ga, after the assembly of the Siberian craton. Synthesis of new and published data for the Sarma rocks allow tracing the Archean-Proterozoic history of the Akitkan orogen, including the pre- and post-orogenic stages of its development.

对西伯利亚克拉通南部阿基特坎造山带Sarma段最古老的变质碎屑岩Khargitui组进行了局部地质、地球化学和年代学研究（LA-ICP-MS U-Pb碎屑锆石年龄）。新的数据揭示了在阿基特坎造山带演化的不同阶段形成的三种岩石单位。第1单元主要包括来自2.7-2.5 Ga多晶砂岩或灰岩的白垩系片麻岩。这些沉积物沉积在由2.88 Ga TTG花岗岩类组成的萨尔马地块基底上，成为碎屑物质的来源。第二单元由石英变质作用产生的石英岩和片岩与多晶砂岩和粉砂岩组成。根据云母-石英片岩碎屑锆石的年龄和变质作用年龄判断，沉积原岩的沉积时间为2.15 ~ 1.95 Ga。在导致阿基特坎造山带形成的碰撞事件发生之前，它是由萨尔马地块内的长英质岩石的破坏维持的。第三单元同样包括石英岩和片岩，但它们来自更成熟的沉积物。碎屑物质主要来源于南西伯利亚岩浆带1.88 ~ 1.84 Ga的岩石，沉积于1.00 ~ 0.72 Ga之间的陆内盆地，是西伯利亚克拉通拼合后形成的。对萨尔马岩石的新数据和已发表的数据进行综合，可以追溯阿基特坎造山带的太古代-元古代历史，包括造山带发育的前和后阶段。

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引用次数: 0

Corrigendum to “Architecture and evolution of the carbonate platform margin of the Lower Cambrian Xiaoerbrak Formation, northwestern Tarim Basin, China” [J. Asian Earth Sci. 274 (2024) 106279] “塔里木盆地西北部下寒武统小尔布拉克组碳酸盐岩台地边缘构造与演化”勘误[J]。亚洲地球科学，274 (2024)106279

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-18 DOI: 10.1016/j.jseaes.2025.106912

Ziyi Wang, Zhiqian Gao, Tailiang Fan

引用次数: 0

The Lithosphere-Atmosphere-Ionosphere coupling (LAIC) processes around the 2024 Wushi (China) Mw7.1 earthquake 2024年中国吴市Mw7.1级地震前后岩石圈-大气-电离层耦合过程

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-16 DOI: 10.1016/j.jseaes.2025.106916

Xuemin Zhang , Angelo De Santis , Pan Xiong , Gianfranco Cianchini , Aisa Yisimayili , Saioa A. Campuzano , Na Yang , Serena D’Arcangelo , Jing Liu , Mariagrazia De Caro , Xinyan Li , Cristiano Fidani , Muping Yang , Martina Orlando , Xinyang Ouyang , Loredana Perrone , Hong Liu , Dario Sabbagh , Maoning Feng , Maurizio Soldani , Shukai Wang

This paper presents a comprehensive analysis on multiple parameters in the lithosphere, atmosphere and ionosphere, around the Wushi M_w7.1 earthquake that occurred on 22 January 2024, in Xinjiang, China. Typical perturbations were picked up with different methods, with a limited time period for lithospheric parameters of longer than 3 years, 90 days before and 10 days after for most atmospheric and ionospheric parameters, in a limited distance within Dobrovolsky’s area of about 1000 km. All the results show that about 60 anomalies were detected before the Wushi earthquake, with medium-term ones lasting about 1 year in the lithosphere, and short-term ones within 3 months in the atmosphere and ionosphere, where the outgoing long wave radiation covered the earthquake occurrence time from four days before to four days after, considered an imminent indicator. The thrust focal mechanism of this earthquake helps to explain the anisotropic feature in Earth’s resistivity and orientation in the electric field, and also the weak variations in the b-value. By combining ground-based and spaceborne observations, a few parameters clearly illustrated the approaching earthquake location, which makes a certain contribution to future earthquake prediction. The accumulating rate of all the anomalies exhibited a fast exponential trend, which illustrates both direct and indirect lithosphere-atmosphere–ionosphere coupling mechanisms during the preparation stage of the Wushi earthquake.

本文对发生在2024年1月22日新疆乌市Mw7.1级地震前后的岩石圈、大气和电离层多个参数进行了综合分析。典型的摄动是用不同的方法采集的，岩石圈参数的时间限制在3年以上，大多数大气和电离层参数的时间限制在90天之前，10天之后，在大约1000公里的Dobrovolsky区域内的有限距离内。结果表明，乌市地震前共探测到60次异常，其中岩石圈中期异常持续1年左右，大气和电离层短期异常持续3个月左右，向外发射的长波辐射覆盖了地震发生前4天至震后4天的时间，可视为即将发生的信号。这次地震的逆冲震源机制有助于解释地球在电场中的电阻率和方位的各向异性特征，以及b值的微弱变化。通过地基观测和星载观测相结合，几个参数清晰地说明了即将来临的地震位置，对未来的地震预报有一定的贡献。所有异常的累积速率均呈快速指数趋势，说明了乌市地震准备阶段岩石圈-大气-电离层的直接和间接耦合机制。

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引用次数: 0

Petrogenesis of early Silurian I-type granitoids in the Nanling domain, South China: implications for the evolution of the Wuyi-Yunkai orogen 南岭地区早志留世ⅰ型花岗岩成因及其对武夷-云开造山带演化的启示

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-16 DOI: 10.1016/j.jseaes.2025.106917

Hai Jiang , Shao-Yong Jiang

A long-standing debate exists over the petrogenesis of Early Paleozoic granites of the South China Block, with the main issue being whether these granites originated from intracontinental orogenic processes. Here, we report new zircon U-Pb geochronology, whole-rock geochemistry, and Sr-Nd-Hf isotope data for two Silurian I-type granitoids in the Nanling domain, South China. The Meiziwo pluton, comprising granodiorite and monzogranite, and the Yaoling quartz porphyry have identical zircon U-Pb ages of ∼ 433 Ma. Rocks of both the Meiziwo and Yaoling plutons have I-type geochemical affinities and are metaluminous to peraluminous in composition (A/CNK = 0.94–1.27). They have low P₂O₅ contents that are negatively correlated with SiO₂. They show chondrite-normalized rare earth element (REE) patterns with LREE enrichment and moderately negative Eu anomalies (Eu/Eu* = 0.50–0.73). They display enrichments in Rb, Th, U, and Pb, and depletions in Ba, Nb, Sr, and Ti in primitive mantle normalized plots. They also have high ⁸⁷Sr/⁸⁶Sr_i ratios (0.712160–0.715776), low ε_Nd(t) (−10.9 to −8.8) and zircon ε_Hf(t) (−12.5 to −6.3) values, indicative of derivation from partial melting of an ancient mafic lower crust, modified by crystal fractionation. The degree of fractionation in the Yaoling quartz porphyry lies intermediate between that of the Meiziwo granodiorite and monzogranite. It is proposed that the Wuyi-Yunkai orogeny originated as an intracontinental orogeny, likely linked to the far-field effects of plate interaction along the northern margin of eastern Gondwana. Widespread post-orogenic felsic magmatism with subordinate mafic components (ca. 435–415 Ma) marks a tectonic transition from compression to extension. This shift is interpreted to reflect lithospheric delamination and the initiation of intracontinental extension in the region.

关于华南地块早古生代花岗岩的岩石成因一直存在争议，主要争论的焦点是这些花岗岩是否起源于陆内造山作用。本文报道了南岭地区2个志留系i型花岗岩的锆石U-Pb年代学、全岩地球化学和Sr-Nd-Hf同位素数据。由花岗闪长岩和二长花岗岩组成的梅子窝岩体与耀岭石英斑岩锆石U-Pb年龄相同，均为~ 433 Ma。梅子窝和窑岭岩体的岩石具有i型地球化学亲和性，在组成上为铝质-过铝质（A/CNK = 0.94 ~ 1.27）。P2O5含量低，与SiO2呈负相关。稀土元素呈球粒正态化模式，LREE富集，Eu中负异常（Eu/Eu* = 0.50 ~ 0.73）。原始地幔归一化区Rb、Th、U、Pb富集，Ba、Nb、Sr、Ti缺失。它们具有较高的87Sr/86Sri比值（0.712160 ~ 0.715776），较低的εNd(t)值（- 10.9 ~ - 8.8）和锆石εHf(t)值（- 12.5 ~ - 6.3），表明它们来源于古基性下地壳的部分熔融，并经过晶体分选修正。窑岭石英斑岩的分选程度介于梅子窝花岗闪长岩和二长花岗岩之间。武夷-云凯造山运动起源于陆内造山运动，可能与冈瓦纳东部北缘板块相互作用的远场效应有关。广泛的造山后长英质岩浆活动（约435 ~ 415 Ma）标志着构造由挤压向伸展转变。这种转变被解释为反映了岩石圈的剥离和该地区大陆内伸展的开始。

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引用次数: 0

Fe occupancy in zoned ferroan dolomite and its constraints on dolomite ordering process: a case study on micritic dolostone of Ordovician Majiagou formation in eastern Ordos Basin, China 带状铁质白云岩中铁的占比及其对白云岩排序的制约——以鄂尔多斯盆地东部奥陶系马家沟组泥晶白云岩为例

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-15 DOI: 10.1016/j.jseaes.2025.106915

Zhenmeng Sun , Xiangjie Cui , Xin Liu , Huan Liu , Xiancai Lu

The cation ordering mechanism and their influence on crystal structure evolution remain poorly understood. This study investigates the oscillatory zoned ferroan dolomite within moldic pores of micritic dolostone from the Ordovician Majiagou Formation in the eastern Ordos Basin, focusing on the site preference, distribution patterns of Fe in the dolomite structure, and its impact on the cation ordering process. Results show that from core to rim, the zoning exhibits increasing Fe content (0.27 mol%, 7.36 mol%, 10.55 mol%) with a corresponding decrease in Mg. Fe substitution primarily influences M–O bond lengths, leading to systematic changes in unit cell parameters: the a/b lattice parameters increase from 4.8066 Å to 4.8234 Å, the c lattice parameter from 16.0051 Å to 16.0690 Å, and the unit cell volume expands by approximately 1.1 %. Uniform strontium isotope compositions of the three zones indicate a homogeneous pore fluid derived from seawater. Further analysis via EXAFS spectroscopy, AC-TEM observation, and DFT calculations confirms that Fe²⁺ preferentially occupies Mg sites and tends to aggregate within Mg layers, forming nanoscale modulated structures and ordered domains. This causes local lattice distortion and defects, reducing the cation ordering degree from 0.45 to 0.30, while these regions may act as preferential sites for ordering progression. The study suggests that local migration and redistribution of trace elements in dolomite may facilitate structural ordering evolution. These findings provide a new crystal defect dynamics perspective for interpreting dolomite structural evolution, contributing to a better understanding of the “dolomite problem”.

阳离子的排序机制及其对晶体结构演化的影响尚不清楚。以鄂尔多斯盆地东部奥陶系马家沟组泥晶白云岩为研究对象，研究了白云岩结构中铁元素的位置偏好、分布规律及其对阳离子有序过程的影响。结果表明：从岩心到边缘，铁含量依次增加（0.27 mol%, 7.36 mol%, 10.55 mol%）， Mg含量相应降低；Fe取代主要影响M-O键长度，导致单元胞参数发生系统性变化：a/b晶格参数从4.8066 Å增加到4.8234 Å， c晶格参数从16.0051 Å增加到16.0690 Å，单元胞体积扩大了约1.1%。三个带的锶同位素组成均匀，表明孔隙流体来源于海水。通过EXAFS光谱、AC-TEM观察和DFT计算进一步分析证实，Fe2+优先占据Mg位点，并倾向于在Mg层内聚集，形成纳米级调制结构和有序畴。这导致了局部晶格畸变和缺陷，使阳离子有序度从0.45降低到0.30，而这些区域可能是有序进展的优先位点。研究表明，微量元素在白云岩中的局部迁移和再分配可能促进了构造的有序演化。这些发现为解释白云岩结构演化提供了新的晶体缺陷动力学视角，有助于更好地理解“白云岩问题”。

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引用次数: 0

Trace element geochemistry of magnetite and hematite from the Jinchang porphyry Au-Cu deposit, northeast China: Implications for fluid evolution and cobalt enrichment 金昌斑岩型金铜矿磁铁矿和赤铁矿微量元素地球化学特征及其流体演化和钴富集意义

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-12 DOI: 10.1016/j.jseaes.2025.106914

Peng-Fei Shan , Ming-Jian Cao , Noreen J. Evans , Le Wang , Yi Li , Yu-Suo Zhao , Ke-Zhang Qin

The Jinchang porphyry Au-Cu deposit in Northeast China has recently shown significant cobalt (Co) enrichment. Before the precipitation of Co-rich sulfides during the main mineralization stage, magnetite and hematite precipitation occurred. Based on the different morphological characteristics of magnetite, it can be classified into mushketovite Mag1 (aspect ratio > 5) and granular Mag2 (aspect ratio < 2) and further subdivided into four subtypes: Mag1-1, Mag1-2, Mag2-1 and Mag2-2. The platy Mag1 is mushketovite, replacing early hematite. The granular Mag2, with well-defined 120° triple junction textures, formed through fluid-assisted recrystallization processes. Mag1 has a trace element composition very similar to the precursor hematite, indicating that the trace element characteristics of Mag1 were inherited from hematite and do not reflect the trace element composition of the fluid at the time of its formation. Mag2 has higher contents of Ti, V, Al, Mg, Si, Mn, Co and Ni, reflecting the trace element characteristics of the fluid in equilibrium with Mag2 during its formation. The early precipitation of magnetite and hematite can effectively inhibit the premature incorporation of Co into sulfides, thereby promoting pre-enrichment of Co in the fluid. While the precipitation of magnetite and hematite can increase the Co/Fe ratio in the residual fluid, it does not directly cause the high Co enrichment in sulfides within the Jinchang deposit. However, the precipitation of magnetite facilitates the migration of Co from mafic magma into ore-forming fluids under acidic and oxidizing conditions, which may be a contributing factor to the Co enrichment in Jinchang deposit.

东北金昌斑岩型金铜矿床近年来钴（Co）富集显著。主成矿阶段富钴硫化物析出前，有磁铁矿和赤铁矿析出。根据磁铁矿的不同形态特征，可将其划分为mushketovite Mag1（长径比>； 5）和粒状Mag2（长径比<； 2），并进一步细分为Mag1-1、Mag1-2、Mag2-1和Mag2-2 4个亚型。板状Mag1为mushketovite，取代了早期赤铁矿。通过流体辅助再结晶过程形成具有明确的120°三重结织构的粒状Mag2。Mag1的微量元素组成与前驱赤铁矿非常相似，说明Mag1的微量元素特征是继承自赤铁矿，并不能反映其形成时流体的微量元素组成。Mag2具有较高的Ti、V、Al、Mg、Si、Mn、Co和Ni含量，反映了流体在形成过程中与Mag2处于平衡状态的微量元素特征。磁铁矿和赤铁矿的早期沉淀可有效抑制Co过早混入硫化物中，从而促进流体中Co的预富集。磁铁矿和赤铁矿的析出可以提高残余流体中的Co/Fe比，但不能直接导致金场矿床内部硫化物中Co的高富集。而磁铁矿的沉淀使Co在酸性和氧化条件下从基性岩浆中迁移到成矿流体中，这可能是金厂矿床Co富集的一个因素。

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引用次数: 0

The botryoidal dolomite of the Ediacaran Dengying Formation (Yangtze Craton): Multi-proxy constraints on the terminal Neoproterozoic “dolomite sea” 埃迪卡拉系扬子克拉通灯影组盆状白云岩：新元古代末期“白云岩海”的多代理约束

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-11 DOI: 10.1016/j.jseaes.2025.106911

Yao Wang , Wenlong Ding , Ziyou Zhang , Shuaiyu Shi , Rui Xia , Mengyang Zhang , Hao Jian

The botryoidal dolomite within the Ediacaran Dengying Formation (Yangtze Craton, South China) represents distinctive features whose origins remain debated, having been variously interpreted as synsedimentary precipitates or as products of dolomitization on a carbonate platform. Detailed petrographic examination reveals two distinct subtypes based on crystal morphology and optical properties: fascicular slow dolomite (FSD) and radial slow dolomite (RSD). Integrated petrographic and geochemical analyses (δ¹³C, δ¹⁸O, rare earth element plus yttrium [REY] patterns, Y/Ho ratios, and clumped isotopes Δ47) constrain their contrasting origins. FSD—characterized by sinistral undulose extinction, dull-red to non-luminescence, relatively stable δ¹⁸O values (mean −2.76 ‰, VPDB), seawater-like REY patterns, and high Y/Ho ratios (≈ 38)—indicates precipitation from primary Dengying Formation seawater. Conversely, RSD exhibits straight extinction, euhedral rhombohedral terminations with bright luminescence, more negative δ¹⁸O values (mean −4.05 ‰, VPDB), positive Eu anomalies (Eu/Eu* = 1.41), and yields a clumped isotope temperature (T_Δ47) of 98 °C. These characteristics collectively demonstrate that RSD precipitated from fluids resulting from the mixing of seawater with hydrothermal fluids. The distinct origins of FSD and RSD provide crucial evidence for the ‘dolomite sea’ hypothesis, indicating it was not uniformly persistent during the Ediacaran on the Yangtze Craton. FSD precipitation reflects an anoxic, alkaline marine environment, while RSD preserves evidence for episodic hydrothermal activity within this Ediacaran ‘dolomite sea’. This challenges the paradigm of uniform marine conditions during the Precambrian–Cambrian transition. Our findings highlight botryoidal dolomite as a sensitive archive of fluid–rock interactions, offering valuable insights into paleoenvironmental perturbations preceding the Cambrian explosion.

埃迪卡拉系灯影组（中国南方扬子克拉通）的盆状白云岩具有独特的特征，其起源仍有争议，有不同的解释，可能是同沉积沉淀，也可能是碳酸盐台地上白云化的产物。详细的岩石学检查显示，基于晶体形态和光学性质的两个不同亚型：束状慢白云岩（FSD）和径向慢白云岩（RSD）。综合岩石学和地球化学分析（δ13C, δ18O，稀土元素加钇[REY]模式，Y/Ho比和团块同位素Δ47）限制了它们的对比来源。fsd的特征是左旋不灭光，暗红色到不发光，δ18O值相对稳定（平均- 2.76‰，VPDB），类似海水的REY模式，高Y/Ho比（≈38），表明降水来自初代灯影组海水。相反，RSD表现为直线消光，自面体菱形末端发光明亮，δ18O值偏负（平均- 4.05‰，VPDB）， Eu正异常（Eu/Eu* = 1.41），团块同位素温度（TΔ47）为98℃。这些特征共同表明，RSD是由海水与热液混合产生的流体沉淀而成。FSD和RSD的不同起源为“白云岩海”假说提供了重要证据，表明它在埃迪卡拉纪的扬子克拉通上并不是统一存在的。FSD降水反映了缺氧、碱性的海洋环境，而RSD则保留了埃迪卡拉纪“白云岩海”中间歇性热液活动的证据。这挑战了前寒武纪-寒武纪过渡时期统一海洋条件的范式。我们的发现突出表明，盆状白云岩是流体-岩石相互作用的敏感档案，为寒武纪大爆发前的古环境扰动提供了有价值的见解。

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引用次数: 0

Constraints of newly discovered Late Triassic andesites in the South Qiangtang Block (Tibet) on the evolution of the Bangong-Nujiang Tethyan ocean

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-11 DOI: 10.1016/j.jseaes.2025.106913

Chenghui Hu , Jian Wang , Lijun Shen , Ahmed Mansour , Shuang Pan , Shengwu Cheng , Yushan Zhang

The tectonic evolution of the Bangong–Nujiang Tethyan Ocean (BNTO), a key component of the eastern Tethyan realm, provides crucial insights into the geological evolution of the Qiangtang Basin and the reconstruction of the Tethyan paleogeographic framework. However, the magmatic response to the initiation of BNTO subduction remains poorly constrained, hindering efforts to reconstruct its tectonic evolution and decipher the Mesozoic tectonic setting of the Qiangtang Basin. We present whole-rock geochemistry, Sr–Nd isotopes, and zircon U–Pb ages for newly discovered andesites from Zhaquxiang, located along the southern margin of the Qiangtang Basin. The andesites formed during the Late Triassic (211.5 ± 4.8 Ma) and display arc-type geochemical signatures characterized by pronounced LREE–HREE fractionation, enrichment in LILEs, and depletion in HFSEs. They show relatively low initial ⁸⁷Sr/⁸⁶Sr ratios (0.704755−0.704966) and positive ε_Nd(t) (+2.63 to +4.37). The andesites have high contents of SiO₂ (61.5–62.7 wt%) and Al₂O₃ (17.3–17.8 wt%), but low values of Mg^# (31–40), K₂O (2.0–2.2 wt%), Cr (30–38 ppm), and Ni (21–24 ppm). They exhibit low Ba/Th and Ba/La, but high Th/Nd and (La/Sm)_N ratios. These characteristics suggest that the andesites were derived from partial melting of subducted oceanic crust, triggered by the initial northward ocean–continent subduction of the BNTO. The onset of BNTO subduction is thus constrained to ca. 211.5 Ma, contemporaneous with the development of a back-arc rift basin tectonic system in the Qiangtang Basin.

班公-怒江特提斯洋（BNTO）是特提斯东部领域的重要组成部分，其构造演化为羌塘盆地地质演化和特提斯古地理格局的重建提供了重要依据。然而，对BNTO俯冲起始的岩浆响应仍知之甚少，这阻碍了重建其构造演化和破译羌塘盆地中生代构造背景的努力。研究了羌塘盆地南缘扎曲乡安山岩的全岩地球化学特征、Sr-Nd同位素和锆石U-Pb年龄。该安山岩形成于晚三叠世（211.5±4.8 Ma），具有明显的LREE-HREE分馏、LILEs富集、HFSEs亏缺的弧型地球化学特征。它们的初始87Sr/86Sr比值较低（0.704755 ~ 0.704966），εNd(t)正（+2.63 ~ +4.37）。安山岩中SiO2 （61.5 ~ 62.7 wt%）和Al2O3 （17.3 ~ 17.8 wt%）含量较高，Mg#（31 ~ 40）、K2O （2.0 ~ 2.2 wt%）、Cr （30 ~ 38 ppm）和Ni （21 ~ 24 ppm）含量较低。它们具有较低的Ba/Th和Ba/La比值，而较高的Th/Nd和（La/Sm）N比值。这些特征表明，这些安山岩是由北北洋陆俯冲引起的洋壳部分熔融形成的。因此，BNTO俯冲的起始时间限定在211.5 Ma左右，与羌塘盆地弧后裂谷盆地构造体系发育同期。

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引用次数: 0

Tectonic control on the channel offset orientations in the Ganga foreland basin: A neotectonic perspective 构造对恒河前陆盆地河道偏移方向的控制：新构造视角

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-06 DOI: 10.1016/j.jseaes.2025.106903

Rahul K. Choudhury , Pitambar Pati , Narendra K. Patel , Manoj K. Jaiswal

The current study in the Ganga foreland basin used 2202 channel offset orientations to establish their relationship with the neotectonics. The variation of the offset orientations acknowledge the directions of plate motion, regional stress field, compressional and extensional structures, subsurface basement ridges, and faults in the foreland. 53.52% offsets are aligned along the NE-SW, i.e., parallel to the plate movement direction, while the rest are aligned NW-SE, i.e., parallel to the Himalayan compressional trend, with the highest concentration along the N40°-60°E and N40°-60°W. The NW-SE stress imposed by the Indian plate’s compression develops various parallel faults and joints, followed by the channel offsets. The decreasing compression intensity away from the Himalayas creates fewer offsets parallel to it, and this trend continues up to the Delhi-Sargodha Ridge’s (DSR) influence at the basin’s southern edge. The NE-SW offsets in the central Ganga basin are influenced by the NE-SW trending faults and basement ridges. The variable strike-slip components along the basement faults contribute to the NE-SW offsets. More NW-SE offsets in the eastern part of the basin are correlated with a larger crustal shortening rate than the western part. The Yamuna-Ganga, Ganga-Ghaghara, Ghaghara-Rapti, Rapti-Gandak, and Gandak-Kosi interfluves record 42.67%, 43.66%, 42.31%, 50.17%, and 55.08% of offsets in NW-SE quadrants, respectively. The E-W trending longer offsets generally seen at the basin’s periphery are due to the strike-slip displacement. However, the E-W offsets in the eastern part of the basin are due to the shallow subsurface thrust splays parallel to the Himalayan Frontal Thrust (HFT).

目前对恒河前陆盆地的研究采用2202水道偏移方向来确定其与新构造的关系。偏移方向的变化反映了板块运动方向、区域应力场方向、挤压伸展构造方向、地下基底脊方向和前陆断裂方向。53.52%的偏移沿NE-SW方向排列，即平行于板块运动方向，其余偏移沿N40°-60°E和N40°-60°W方向排列，即平行于喜马拉雅挤压走向。受印度板块挤压作用的北西-东向应力作用，形成了多种平行断裂和节理，随后形成了河道偏移。远离喜马拉雅山脉的压缩强度降低，与之平行的偏移量减少，这一趋势一直持续到盆地南部边缘的德里-萨戈达脊（DSR）的影响。恒河盆地中部的北东-西向偏移受北东-西向断裂和基底隆起的影响。基底断裂的走滑分量变化导致北东向西向偏移。盆地东部北西-东向偏移多，地壳缩短速率大于西部。亚木纳-恒河、恒河-加加拉、加加拉-拉普提、拉普提-甘达克和甘达克-科西断流分别占西北-东南象限偏移量的42.67%、43.66%、42.31%、50.17%和55.08%。在盆地外围普遍出现的东西向较长偏移是由走滑位移引起的。而盆地东部的东西向偏移是由于与喜马拉雅锋面逆冲平行的浅层地下逆冲展布所致。

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引用次数: 0