Journal of Asian Earth Sciences最新文献_第5页

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

New paleoseismological constraints on the seismic activity along the eastern Tunka Fault (SW Baikal Rift) 东通卡断裂带（西南贝加尔湖裂谷）地震活动的古地震学新约束

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-04 DOI: 10.1016/j.jseaes.2025.106901

A.A. Chebotarev , A.V. Arzhannikova , S.G. Arzhannikov , J.-F. Ritz , A.V. Avagyan

The Tunka Fault, a major active structure in the southwestern Baikal Rift system, poses a significant seismic hazard, yet its paleoseismic history remains poorly constrained. We present new paleoseismic data from trenches across its eastern Tory segment, constrained with morphotectonic analysis and radiocarbon dating. Our results reveal two Holocene earthquakes, corresponding to the E2 and E3 events identified in previous studies along the Mondy, Tunka, and Main Sayan faults. These three faults have been interpreted as having produced seismic clusters at least four times in the Late Pleistocene-Holocene times. Our radiocarbon data allow constraining more tightly the ages of the E2 and E3 events to 3170–3399 and 8453–8540 cal yr BP, respectively. Morphotectonic analysis of the Tory site, together with published data along the adjacent section of the Tunka Fault, showed that the average amplitude of displacement per event along the slip vector was 2.1 m, corresponding to a magnitude of Mw 7.3. In some cases, all fault segments seem to have ruptured simultaneously over a length of 200 km, while in others cases, only segments striking E-W and NW-SE directions ruptured with a reverse slip component. Fault segments with normal slip component ruptured with a delay, but with a similar recurrence interval. These results highlight the potential for multi-fault ruptures in the Baikal region and challenge existing seismic hazard models. Our study provides critical input for revising probabilistic seismic hazard assessments and underscores the need to consider fault interaction in tectonic settings with complex block boundaries.

Tunka断裂是贝加尔湖裂谷系西南部的一个主要活动构造，具有重大的地震危险性，但其古地震史却知之甚少。通过形态构造分析和放射性碳定年，我们提出了新的古地震数据，这些数据来自东托里段的沟槽。我们的研究结果揭示了两个全新世地震，对应于先前研究中发现的沿着Mondy， Tunka和Main Sayan断层的E2和E3事件。这三条断层被解释为在晚更新世-全新世期间至少四次产生了地震群。我们的放射性碳数据可以更严格地将E2和E3事件的年龄分别限制在3170-3399和8453-8540 calyr BP之间。托里地区的形态构造分析，连同Tunka断层邻近部分的已发表数据，表明沿滑动矢量每次事件的平均位移幅度为2.1 m，相当于7.3 Mw的震级。在某些情况下，所有断层段似乎在200公里长的范围内同时破裂，而在其他情况下，只有E-W和NW-SE方向的断层段破裂，并伴有逆滑成分。具有正常滑动分量的断层段的破裂具有延迟性，但具有相似的复发间隔。这些结果突出了贝加尔湖地区多断层破裂的可能性，并对现有的地震危险性模型提出了挑战。我们的研究为修正概率地震危险性评估提供了关键的输入，并强调了在具有复杂块体边界的构造环境中考虑断层相互作用的必要性。

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引用次数: 0

Insights on the structural framework of the Ailaoshan Orogenic Belt from gravity data 从重力资料看哀牢山造山带构造格架

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-03 DOI: 10.1016/j.jseaes.2025.106902

Nguyen Ngoc Long , David Gomez-Ortiz , Nguyen Kim Dung , Luan Thanh Pham

One of the important tasks in mapping geological structures is determining the horizontal boundaries of density structures. These boundaries can be estimated by using the edge detection techniques of gravity data. In this study, we apply several traditional edge enhancement filters along with recently developed techniques to the Bouguer gravity data to analyze structural trends and fault zones in the Ailaoshan Orogenic Belt, which is known as a significant suture zone between the South China Block and the Indochina Block. The edge recognition capabilities of these filters are examined using both noise-free and noisy synthetic gravity data before applying them to real gravity anomaly data of the belt. The structural features from the edge detection techniques are also confirmed by the Euler deconvolution method, where the result shows that the depth estimates in the Ailaoshan Orogenic Belt change from 0.9 to 4.7 km. The findings show that edge detection techniques produce anomaly maps that are well-correlated with the main tectonic framework of the study area, which trends NW-SE. These techniques are also helpful in identifying some structural features that are not visible at the surface, thus contributing to a more complete crustal framework of the Ailaoshan Orogenic Belt.

地质构造填图的重要任务之一是确定密度构造的水平边界。这些边界可以用重力数据的边缘检测技术来估计。本文将几种传统的边缘增强滤波方法与最新发展的布格重力数据相结合，对哀牢山造山带的构造走向和断裂带进行了分析。哀牢山造山带是华南地块和印度支那地块之间的重要缝合带。在将这些滤波器应用于实际重力异常数据之前，分别使用无噪声和有噪声的合成重力数据对其边缘识别能力进行了检验。欧拉反褶积方法也证实了边缘检测技术的构造特征，结果表明哀牢山造山带的深度估计在0.9 ~ 4.7 km之间变化。结果表明，边缘检测技术得到的异常图与研究区北西-东向的主构造格架具有较好的相关性。这些技术还有助于识别一些地表不可见的构造特征，从而使哀牢山造山带的地壳格架更加完整。

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引用次数: 0

Constraints of the paleo-trade wind route on the paleo-geography of the South China Block in the Late Permian (Lopingian)-Early Triassic 晚二叠世（洛平纪）-早三叠世古信风路径对华南地块古地理的制约

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-03 DOI: 10.1016/j.jseaes.2025.106900

Rufei Peng , Chenlin Hu , Xin Li , Hongmei Su , Jonathan Atuquaye Quaye , Cheng Dong

South China Block (SCB) is situated in the Eastern Asian margin. During the crucial transitional Formation of the Permian-Triassic boundary in geological history, the SCB was located in a shallow sea environment within the low-latitude trade winds zone, accumulating marine sedimentary deposits. There are numerous studies concerned on the paleoecological and biological evolution of the SCB, but studies of paleogeography are few and the paleogeographic position of the SCB remains as a matter of debate. In this paper, we describe the sedimentary features of Late Permian (Lopingian) to Early Triassic in the Sichuan Basin, northwestern SCB, and present new magnetic fabrics for these sequences. The results of sedimentary differentiation and anisotropy of magnetic susceptibility indicated prevailing wind routes of 106.6° ± 4.3° east of north in the Late Permian and 118.2° ± 4.7° east of north in the Early Triassic. After correcting for a 70° clockwise rotation of the SCB since the Permian-Triassic boundary, the paleo-wind routes are reconstructed as 36.6° ± 4.3° and 48.2° ± 4.7° east of paleo-north for these periods. The study of the paleo-wind routes indicates that the SCB migrated northward from a near-equatorial position in the Late Permian (Lopingian) to a more distant location in the Early Triassic, marking significant movement within the Northern Hemisphere. The paleogeographic position of the SCB was determined by aligning its quantitatively reconstructed predominant paleo-wind routes with the latitudinal variation of Northern Hemisphere trade wind patterns. This analysis indicates that the SCB was located near the equator in the Late Permian and had migrated northward within the Northern Hemisphere by the Early Triassic. These findings provide insights into the paleoclimate and paleogeographic evolution of the SCB and offer data for other studies. Moreover, the methodology employed in this study serves as a useful reference for paleogeographic and paleoclimatic reconstructions of other ancient landmasses.

华南地块（SCB）位于东亚边缘。在地质历史上二叠纪-三叠纪界线的关键过渡期，南海处于低纬度信风带内的浅海环境，聚集了海相沉积。近年来，学界对其古生态和生物演化的研究较多，但对其古地理的研究较少，对其古地理位置的研究也存在争议。本文描述了华南西北地区四川盆地晚二叠世（洛平期）至早三叠世的沉积特征，并提出了这些层序的新磁组构。沉积分异和磁化率各向异性结果表明，晚二叠世盛行风路径为北偏东106.6°±4.3°，早三叠世盛行风路径为北偏东118.2°±4.7°。在校正了自二叠纪—三叠纪界线以来SCB的顺时针旋转70°后，重建的古风路径为古北偏东36.6°±4.3°和48.2°±4.7°。古风路研究表明，SCB在晚二叠世（洛平纪）从近赤道位置向北迁移到早三叠世较远的位置，标志着北半球内的重大运动。通过将定量重建的主要古风路与北半球信风型的纬向变化进行比对，确定了南海的古地理位置。这一分析表明，SCB在晚二叠世时位于赤道附近，并在早三叠世时在北半球向北迁移。这些发现为研究南海的古气候和古地理演化提供了新的思路，并为其他研究提供了数据。此外，本文所采用的方法对其他古陆块的古地理和古气候重建也有借鉴意义。

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引用次数: 0

Tectonic and climate control on the stratigraphic cycles in a Late Paleozoic evaporitic basin in NW China 构造和气候对西北晚古生代蒸发盆地地层旋回的控制

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-02 DOI: 10.1016/j.jseaes.2025.106898

Kuanhong Yu , Shuo Du , Yingchang Cao , Zi Wang

The Fengcheng Formation in the Junggar Basin, northwestern China, represents a suite of deposits formed in a hydrologically closed, alkaline saline lake during the Late Paleozoic. This formation hosts high-quality source rocks (oil shales) and significant trona resources. Closed-basin lacustrine systems exhibit stratigraphic architectures that are fundamentally distinct from those of marine or open-lake settings; consequently, conventional sequence stratigraphic models are often inadequate for interpreting the distribution of trona and oil shale resources within such confined depositional systems. Based on integrated analyses of drilling sequences, well logs, and seismic profiles, we identify four key findings: (1) Three third-order sequences can be delineated using lithostratigraphic patterns and seismic-stratigraphic relationships; (2) The Mahu Sag remained predominantly underfilled throughout most of the depositional history, evolving into a balanced-fill basin only at the end of Sequence 3 (SQ3); (3) Trona deposition occurred during arid phases within repeated climatic cycles, with the Fengcheng Formation preserving four long-term cycles, each comprising multiple intermediate- and short-term climatic fluctuations; (4) The highest-quality oil shales accumulated during the transgressive systems tracts (TST) of SQ1 and SQ2, coinciding with periods of rising lake levels. Additional oil shale intervals formed at the onset of individual cycles when lake levels were elevated. These findings offer a comprehensive stratigraphic framework for understanding the spatial and temporal distribution of trona and oil shale resources in a Late Paleozoic alkaline saline lake system characterized by asymmetric basin geometry.

准噶尔盆地丰城组是一套晚古生代水文封闭的碱性盐湖沉积。该地层拥有优质烃源岩（油页岩）和重要的天然气资源。封闭盆地湖泊体系的地层结构与海相或开阔湖泊的地层结构有本质的区别；因此，常规的层序地层学模型往往不足以解释此类封闭沉积体系中地下和油页岩资源的分布。通过对钻井序列、测井曲线和地震剖面的综合分析，得出了四个重要发现：(1)利用岩石地层模式和地震-地层关系圈定了3个三级层序；(2)马湖凹陷在大部分沉积历史中以欠充填为主，仅在层序3 （SQ3）末演化为平衡充填盆地；(3) Trona沉积发生在干旱期，在重复的气候周期中，丰城组保存了4个长期周期，每个周期包含多个中短期气候波动；(4)油页岩质量最高的时期为SQ1和SQ2海侵体系域（TST），与湖泊水位上升时期一致。当湖泊水位升高时，在个别旋回开始时形成额外的油页岩层段。这些发现为认识具有不对称盆地几何特征的晚古生代碱性盐湖体系中烃类和油页岩资源的时空分布提供了一个全面的地层框架。

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引用次数: 0

Jurassic tectonic activity and geodynamic implications of the eastern segment of the Altyn Tagh Fault, Northwest China 阿尔金断裂带东段侏罗系构造活动及其地球动力学意义

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-02 DOI: 10.1016/j.jseaes.2025.106899

Huaiwei Feng , Shumei Xu , Jinduo Wang , Hongzhuang Cui , Xiangfeng Wu

The Altyn Tagh Fault (ATF), forming the northern boundary of the present-day Tibetan Plateau, cuts across multiple structural units of northern Tibetan Plateau and exerts a fundamental control on the framework of the Mesozoic-Cenozoic sedimentary basins. Although numerous studies have investigated the timing and magnitude strike-slip motion along the ATF, its Jurassic evolution remains poorly constrained. In this study, we integrate sedimentological, structural, geophysical, and thermochronological approaches to examine the Jurassic tectonic activity of the eastern segment of the ATF. Analyses of soft-sediment deformation structures indicate that the Altyn Tagh Range experienced incipient, submarine uplift without the development of significant surface topography. The recognition of Jurassic stratigraphic contacts and flower structures in seismic profiles further suggests localized uplift and strike-slip deformation. Detrital zircon U-Pb age spectra exhibit near-source signatures, implying restricted lateral displacement along the fault during the Jurassic. Moreover, aeromagnetic anomaly interpretation combined with low-temperature thermochronology indicates that the ATF operated within a dynamic framework involving pre-Jurassic southward deep subduction of the Tarim Block and northward shallow subduction of the Qaidam Block, mediated by a deep lithosphere-mantle ductile shear zone. Under this tectonic configuration, the fault experienced limited strike-slip motion, segmented activity, and localized uplift during the Jurassic.

尽管许多研究已经调查了沿ATF的走滑运动的时间和规模，但其侏罗纪演化仍然知之甚少。在这项研究中，我们综合了沉积学、构造学、地球物理和热年代学的方法来研究ATF东段的侏罗纪构造活动。软沉积变形构造分析表明，阿尔金山脉经历了早期的海底隆升，没有明显的地表地形发育。地震剖面对侏罗系地层接触和花状构造的识别进一步表明了局部隆升和走滑变形。碎屑锆石U-Pb年龄谱表现出近源特征，表明侏罗纪时期沿断层侧向位移受限。此外，航磁异常解释结合低温热年代学表明，ATF是在塔里木地块前侏罗世向南深俯冲和柴达木地块向北浅俯冲的动力框架内运行的，并以深部岩石圈-地幔韧性剪切带为介质。在这一构造构型下，断层在侏罗纪经历了有限的走滑运动、分段活动和局部隆升。

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引用次数: 0

A refined classification of 3D shape preferred orientation patterns in fault gouges: Insights from the Yangsan and Ulsan Fault Zones, South Korea 断层带中三维形状优选方向模式的精细分类：来自韩国梁山和蔚山断裂带的见解

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-02 DOI: 10.1016/j.jseaes.2025.106896

Ho Sim , Seongsik Hong , Yungoo Song , Seung-Ik Park , Changyun Park

Shape preferred orientation (SPO) analysis of rigid clasts in fault rocks is a fundamental tool for understanding grain-scale deformation process. However, the occurrence of anomalous patterns in 3D-SPO data has challenged traditional interpretations that rely solely on clast rotation systems observed in cross-sections. Here, we present a novel classification system for 3D-SPO patterns that accounts for the critical influence of clast morphology. Through integrated analysis of X-ray diffraction patterns, μ-CT imaging, 3D-SPO analysis, and electron microscopy data for three samples from the Yangsan and Ulsan fault zones (southeastern Korean Peninsula), we demonstrate that clast final shape and fabric under shear are primarily controlled by clast morphology, possibly combined with initial orientation. We classified all samples into four types based on clast morphology and identified six distinct SPO patterns associated with these classifications: top-spinning (type-S) and oblate-rolling (type-OR) for oblate type clasts, rotating (type-R) and prolate-rolling (type-PR) for prolate type clasts, and two distinct rotating patterns (types H and V) for bladed type clasts. Natural fault gouge typically exhibits a composite of these patterns, with the dominant pattern reflecting the predominant clast shape population. This refined understanding of the relationship between clast shape and SPO patterns significantly improves the reliability of SPO analysis and enhances our ability to reconstruct fault deformation process.

断裂岩中刚性碎屑的形状优先取向（SPO）分析是理解颗粒级变形过程的基本工具。然而，3D-SPO数据中出现的异常模式对传统的仅依赖于在横截面上观察到的碎屑旋转系统的解释提出了挑战。在这里，我们提出了一种新的3D-SPO模式分类系统，该系统考虑了碎屑形态的关键影响。通过对梁山和Ulsan断裂带3个样品的x射线衍射图、μ-CT成像、3D-SPO分析和电镜数据的综合分析，我们发现剪切作用下碎屑的最终形态和结构主要受碎屑形态的控制，可能与初始取向有关。我们根据碎屑形态将所有样品分为4种类型，并确定了与这些分类相关的6种不同的SPO模式：扁圆型碎屑的顶旋（s型）和扁圆滚动（or型），长圆型碎屑的旋转（r型）和扁圆滚动（pr型），叶片型碎屑的两种不同的旋转模式（H型和V型）。天然断层泥通常表现为这些模式的组合，主要模式反映了主要的碎屑形状种群。这种对碎屑形状与SPO模式之间关系的精细化理解大大提高了SPO分析的可靠性，增强了我们重建断层变形过程的能力。

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引用次数: 0