Tectonophysics最新文献_第3页

Thermotectonic history of the Longshou Shan: From Paleozoic Tethys subduction to Cenozoic Tibetan Plateau growth

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-11-19 DOI: 10.1016/j.tecto.2024.230560

Ni Tao , Ruohong Jiao , Yiduo Liu , Meinert Rahn , Yunpeng Dong , Hanjie Wen , Haiqing Yan , Jiangang Jiao , Jun Duan , Chen Wang

Constraining exhumation and tectonic processes along an orogenic plateau's boundary provides important insights into the mechanisms leading to plateau expansion and crustal evolution. The Longshou Shan thrust belt (LSSTB) is located in the foreland of the northern Qilian Shan thrust belt, which is commonly regarded as the northeastern margin of the Tibetan Plateau. The LSSTB is thus ideal for decoding the recent expansion of the Tibetan Plateau by tracking deformational pattern at its northeastern margin. In this study, the spatiotemporal characteristics of exhumation and deformation along the LSSTB are investigated by detailed analysis and numerical modeling of published and new thermochronological data. Five Proterozoic basement and intrusion samples yielded Cretaceous apatite fission-track central ages (126–74 Ma, with mean track lengths of 12.6–13.3 μm), and Late Cretaceous to Eocene apatite (UTh)/He mean ages (84–51 Ma). Inverse thermal history modeling reveals multi-stage exhumation of the LSSTB in the Permo-Triassic, late Mesozoic, Paleogene, and post-middle Miocene. Permo–Triassic exhumation hints at a > 250 Ma-old peneplain surface that may have formed in response to the closure of the Paleo-Tethys and Paleo-Asian oceans. Late Mesozoic exhumation likely resulted from intracontinental extensional deformation associated with tectonic processes at the Eurasian continental margin. Exhumation during the Paleogene was likely triggered by the India-Asia collision. Post-middle Miocene periods of uplifts along the reactivated Longshou Shan thrusts (no later than 10 Ma and 5 Ma on the southern and northern Longshou Shan Thrust, respectively) were driven by the northeastward expansion of the Tibetan Plateau. Our results support the LSSTB as a long-lived block boundary since the Permo-Triassic and an emerging plateau boundary that has lately been reactivated by the Tibetan Plateau expansion.

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引用次数: 0

Heterogeneous Seasonal Deformation and Strain Budget in Himachal, NW Himalaya from new cGPS measurements: Hydrological and Seismic Hazard Implications 从新的 cGPS 测量结果看喜马拉雅西北部喜马偕尔地区的异质性季节变形和应变预算：水文和地震灾害的影响

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-11-17 DOI: 10.1016/j.tecto.2024.230561

Prabhat Kumar , Javed N. Malik , Vineet K. Gahalaut

GPS measurements from 10 new permanent sites installed in Himachal, NW Himalaya are analysed with the primary objective to decipher the seasonal crustal deformation characteristics, its origins and hydrological implications. Additionally, we focus on the seismic hazard implications of the seasonal transients as well as of the long-term secular motion of GPS sites. Our findings suggest that the global hydrological loading models can relatively well explain the temporal surface displacements resulting from the monsoon rainfall in the Indo-Gangetic plains (IGP) but poorly account for the winter snowfall in Higher Himalaya. The approximately elliptical horizontal seasonal motion of GPS sites seems to be controlled by the spatio-temporal variations in the monsoonal hydrological load over the IGP. The hydrological process derived from the GPS data suggests slow and steady recovery in the water storage in Himachal Himalaya. The more intriguing phenomena is reflected in the unusually high seasonal site uplift and the yearlong (mid-2020 – mid-2021) plunge in the water storage corresponding to the time-period of COVID-19 lockdown phases, which could be speculated as its indirect impact on the crustal deformation history. The seasonal strain analysis revealed significant spatial heterogeneity. The arc-normal and arc-parallel seasonal strain resulting from differential seasonal motion between GPS sites seems to be primarily localized in the vicinity of locking transition zone, while the locked segment is being largely translated without experiencing significant strain. The localized seasonal strain showed positive correlation with the background seismicity rate suggesting possible modulation of the earthquake nucleation process. The regional seismic hazard assessment suggests susceptibility to a future great earthquake of ∼M_w8.4. The additional observed equivalency between the updated strain budget (∼9.3 m) and the previously reported co-seismic displacement (∼9.3 m) during the last great earthquake around ∼1400–1500 CE, suggests a recurrence interval of ∼600 years for great earthquake events in Himachal Himalaya with significant reliability.

我们分析了喜马拉雅西北部喜马偕尔邦新安装的 10 个永久性站点的 GPS 测量数据，主要目的是解读季节性地壳变形特征、其起源和水文影响。此外，我们还重点研究了全球定位系统站点的季节瞬变和长期静态运动对地震灾害的影响。我们的研究结果表明，全球水文载荷模型可以较好地解释印度-甘肃平原（IGP）季风降雨造成的地表时空位移，但对高喜马拉雅地区的冬季降雪解释不清。全球定位系统站点近似椭圆形的水平季节性运动似乎是由印度洋-甘地平原季风水文负荷的时空变化控制的。从 GPS 数据得出的水文过程表明，喜马偕尔喜马拉雅山的蓄水量在缓慢而稳定地恢复。更耐人寻味的现象是，在 COVID-19 锁定阶段的时间段内，储水量出现异常高的季节性站点抬升和长达一年（2020 年中至 2021 年中）的骤降，这可以推测为其对地壳变形历史的间接影响。季节应变分析显示了显著的空间异质性。GPS站点间不同的季节运动所产生的弧正向和弧平行季节应变似乎主要集中在锁定过渡带附近，而锁定段在很大程度上被平移，没有出现明显的应变。局部季节应变与背景地震率呈正相关，表明地震成核过程可能受到调制。区域地震灾害评估表明，未来可能发生 ∼Mw8.4 级大地震。另外观测到的最新应变预算（∼9.3 米）与之前报告的上一次大地震（约公元 1400-1500 年）期间的共震位移（∼9.3 米）之间的等效性，表明喜马拉雅山脉大地震的重现间隔为 600 年，具有很高的可靠性。

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引用次数: 0

Mantle conduits of the K-Pg Reunion mantle plume rise beneath the Indian subcontinent revealed by 3D magnetotelluric imaging 三维磁强成像揭示印度次大陆下K-Pg团聚地幔羽流上升的地幔导管

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-11-16 DOI: 10.1016/j.tecto.2024.230558

K.K. Abdul Azeez, K. Veeraswamy, Prasanta K. Patro, A. Manglik, Arvind K. Gupta, Prabhakar E. Rao, D. Hanmanthu , B. Manoj Prabhakar , B.D.N. Kishore

The central-western region of the Indian subcontinent hosts the vast geological records of its evolution from the Archean to the Recent, including the youngest (∼65 Ma) episode of the Réunion mantle plume activity that produced a large igneous province, the Deccan Volcanic Province (DVP). A three-dimensional lithospheric resistivity image of central-western India is obtained to understand the lithospheric architecture and map any major eruption channels of the Deccan volcanism as no explicit geophysical revelation of such pathways of magma ascend has yet been made. Two high conductivity (< 30 Ωm) pipe-like geometric features originating from a common deep mantle conductive zone under the Malwa plateau (northernmost lobe of the DVP) and its proximity are detected in the resistivity model. These are interpreted to be remnants of the hitherto unknown primary lithospheric pathways of magma ascent from the deep mantle melt-rich zone related to the Reunion mantle plume upwelling under central-western India. This study gives first compelling geophysical evidence of key eruptive centers of the massive Deccan volcanism in central-western India at a locale not anticipated earlier. High to moderate conductivity crustal zones and weak to moderate lithospheric mantle resistivity in most parts of the study region represent an intense and multiphase tectono-magmatic evolution of the region spanning from the Neoproterozoic to the Cretaceous-Paleogene boundary.

印度次大陆中西部地区承载了其从奥陶纪到近代演变的大量地质记录，包括留尼汪地幔羽流活动的最年轻（65 千兆年）时期，该时期产生了一个大型火成岩区--德干火山省（DVP）。由于尚未从地球物理角度明确揭示岩浆上升的途径，因此获得了印度中西部岩石圈的三维电阻率图像，以了解岩石圈的结构并绘制德干火山活动的任何主要喷发通道。在电阻率模型中探测到了两个高导电率（30 Ωm）的管状几何特征，它们源自马尔瓦高原（德干火山带最北端的叶片）及其附近的一个共同的深地幔导电带。据解释，这些是迄今未知的岩浆从与印度中西部下的留尼汪地幔羽流上涌有关的深地幔富熔带上升的主要岩石圈路径的残留物。这项研究首次提供了令人信服的地球物理证据，证明印度中西部德干火山大规模喷发的关键喷发中心位于早先未曾预料到的位置。在研究区域的大部分地区，地壳的导电率从高到中等，岩石圈地幔的电阻率从弱到强，代表了该区域从新近纪到白垩纪-古近纪边界的强烈和多阶段构造-岩浆演化。

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引用次数: 0

A late Paleogene erosion event in the Sanshui Basin, southern margin of the South China Block and its tectonic significance 华南地块南缘三水盆地古近纪晚期侵蚀事件及其构造意义

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-11-10 DOI: 10.1016/j.tecto.2024.230557

Peng Zhao , Xiaobin Shi , Lu Liu , Kui Liu , Yongqiang Shen , Ziqiang Ren , Xiaoqiu Yang , Yongbin Jin

Ubiquitous onshore Cenozoic basins of the southern margin of the South China Block (SCB) systematically show a stratigraphic hiatus in the sedimentary succession. The absence of strata between the residual Paleogene and the overlying Quaternary in the onshore basin is a serious obstacle to reconstruct their evolutionary history and completely understand the tectonic evolution of the southern SCB margin. Using multiple independent methods, this study reconstructs the entire tectonic subsidence and uplift history in the Sanshui Basin. To do so, we first constrain the eroded thickness and initial erosion time between the Quaternary strata and the residual Huayong Formation (∼41 Ma). The results show that the erosion thickness at the unconformity in the northwestern Sanshui Basin was approximately 2200 m, and the erosion event lasted from approximately 29 Ma to the early Quaternary. The tectonic evolution of the Sanshui Basin during the Paleogene to early Quaternary was characterized by four successive tectonic episodes, three rifting events, and one uplift stage. The first rifting episode lasted from ca. 66–48 Ma, during which approximately 1000 m of tectonic subsidence accommodated the deposition of the Xinzhuangcun (66–59 Ma), Buxin (59–53 Ma), and Baoyue (53–48 Ma) formations. This was followed by the second and third rifting episodes from ca. 48–29 Ma, during which the average tectonic subsidence was approximately 650–850 m, and the residual Huayong Formation (ca. 48–41 Ma) and eroded strata (ca. 41–29 Ma) accumulated. From 29 Ma to the early Quaternary, a tectonic uplift of approximately 1150 m occurred, with a rate of 43 m/Myr, which triggered the erosion of most sediments deposited during the second and third rifting episodes. Our results strongly suggest that although the main depocenters were located offshore since the second rifting episode, rifting in the Sanshui Basin continued until the occurrence of the late Cenozoic erosion event. The differential evolution between uplift (and erosion) onshore and subsidence offshore since the late Paleogene is probably related to the coastward attenuation of southeastern extrusion caused by the Indo–Asian plate collision.

华南断块南缘陆相新生代盆地的沉积演替系统性地出现了地层断裂。陆上盆地中残留的古近纪与上覆第四纪之间地层的缺失，严重阻碍了其演化历史的重建和对华南地块南缘构造演化的全面认识。本研究采用多种独立方法，重建了三水盆地的整个构造沉降和隆升史。为此，我们首先对第四纪地层与残积华容地层（∼41 Ma）之间的侵蚀厚度和初始侵蚀时间进行了约束。结果表明，三水盆地西北部不整合处的侵蚀厚度约为2200米，侵蚀事件持续时间约为29Ma至第四纪早期。三水盆地在古近纪至第四纪早期的构造演化特点是连续发生了四次构造事件，其中三次为断裂事件，一次为隆起阶段。第一次断裂发生在约66-48Ma，在此期间，约1000米的构造下沉容纳了新庄村（66-59Ma）、布心（59-53Ma）和宝月（53-48Ma）地层的沉积。随后，在约 48-29 Ma 的第二次和第三次断裂过程中，平均构造下沉约 650-850 m，残余的华勇地层（约 48-41 Ma）和侵蚀地层（约 41-29 Ma）逐渐堆积。从 29 Ma 到第四纪早期，发生了约 1150 m 的构造隆起，隆起速度为 43 m/Myr，这引发了第二和第三次断裂期间沉积的大部分沉积物的侵蚀。我们的研究结果有力地表明，虽然自第二次断裂以来，主要沉积中心位于近海，但三水盆地的断裂一直持续到新生代晚期侵蚀事件的发生。自晚古新世以来，陆上隆起（和侵蚀）与近海沉降的不同演化可能与印支-亚洲板块碰撞导致的东南挤压向海岸衰减有关。

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引用次数: 0

The improved Moho depth imaging in the Arabia-Eurasia collision zone: A machine learning approach integrating seismic observations and satellite gravity data 阿拉伯-欧亚大陆碰撞带莫霍深成像的改进：整合地震观测和卫星重力数据的机器学习方法

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-11-07 DOI: 10.1016/j.tecto.2024.230553

Vahid Teknik

The Arabia-Eurasia convergences created one of the earth's topographic highs on the Central Tethys collisional belt. Despite the area's geological significance, a comprehensive and high-resolution map of Moho depth has been lacking due to the sparse and uneven distribution of seismically constrained Moho depth data. This study addresses this deficiency by compiling an extensive dataset of nearly 2500 seismically measured Moho depth points from 68 seismic local scale studies, resulting in the development of an updated seismically constrained Moho depth model (S-Moho) at a 0.5° × 0.5° spatial resolution. Despite some coverage gaps in the remote areas, the S-Moho model offers a more detailed view than previously available. To further improve the coverage of the S-Moho depth model, an incremental data-driven approach was employed. Initially, a gravity-based regression Moho depth model (SB-Moho) was developed by correlating S-Moho depth points with corresponding Bouguer anomalies. However, its accuracy was constrained by unaccounted isostatic and non-isostatic components. To address this limitation, a sliding window approach was applied to derive a windowed SB-Moho model (WSB-Moho). Additionally, a machine learning-based Moho model (ML-Moho) was developed using seismic Moho depth points along with 11 predictive variables. Both WSB-Moho and ML-Moho models demonstrated consistent and smooth Moho depth variations. The Zagros region reveals a prominent NW-SE oriented Moho depression (45-60 km thick), attributed to the underthrusting of the Arabian Plate beneath the Iranian Plateau. The models suggest that crustal thickening extends beyond tectonic boundaries, likely influenced by the dip of suture zones. In contrast, the crustal thickening in eastern Anatolia, northwest of the Zagros, is less pronounced, indicating different geodynamic processes. Strike-slip faulting and magmatic activity in this area contribute to a broader distribution of deformation compared to the more localized crustal thickening in the Zagros. In southeastern Zagros, strike-slip faults in central Iran accommodate much of the northward convergence of the Arabian Plate, thereby limiting the extent of crustal thickening.

阿拉伯-欧亚大陆的汇聚形成了特提斯碰撞带中部的地形高地之一。尽管该地区具有重要的地质意义，但由于地震约束莫霍深度数据稀少且分布不均，一直缺乏全面、高分辨率的莫霍深度图。本研究针对这一不足，汇编了来自 68 个地震局部尺度研究的近 2500 个地震测量莫霍深度点的广泛数据集，从而建立了 0.5° × 0.5° 空间分辨率的最新地震约束莫霍深度模型（S-Moho）。尽管在偏远地区存在一些覆盖缺口，但 S-Moho 模型提供了比以前更详细的视图。为了进一步提高 S-Moho 深度模型的覆盖范围，采用了数据驱动的渐进方法。最初，通过将 S-Moho 深度点与相应的布格尔异常点相关联，建立了基于重力的回归莫霍深度模型（SB-Moho）。然而，其准确性受到了等静力和非等静力成分的制约。为解决这一局限性，采用了滑动窗口法，得出了一个窗口 SB-Moho 模型（WSB-Moho）。此外，利用地震莫霍深度点和 11 个预测变量，开发了基于机器学习的莫霍模型（ML-Moho）。WSB-Moho 和 ML-Moho 模型都显示出一致而平滑的莫霍深度变化。扎格罗斯地区显示出明显的西北-东南走向莫霍凹陷（厚 45-60 公里），这是由于伊朗高原下的阿拉伯板块发生了下推作用。这些模型表明，地壳增厚延伸到了构造边界之外，很可能受到缝合带倾角的影响。相比之下，扎格罗斯山脉西北部安纳托利亚东部的地壳增厚没有那么明显，这表明了不同的地球动力过程。与扎格罗斯地区较为局部的地壳增厚相比，该地区的走向滑动断层和岩浆活动导致了更广泛的变形分布。在扎格罗斯东南部，伊朗中部的走向滑动断层容纳了阿拉伯板块向北辐合的大部分，从而限制了地壳增厚的范围。

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引用次数: 0

Top-to-south shear at the base of the eastern Tethyan Himalayan Sequence during the Eocene-Oligocene Himalayan orogeny

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-11-06 DOI: 10.1016/j.tecto.2024.230552

Zhiqin Xu , An Yin , Hua Xiang , Qin Wang , Guangwei Li , Hanwen Dong , Hui Cao , Jianguo Gao

The early mountain building processes in the Himalayan orogen are still not clear because of extensive deformation and metamorphism since the Miocene. A large gently dipping ductile shear zone, referred as the Tethyan Himalayan Décollement (THD), is defined here as the sole décollement of the south-verging Tethyan fold-and-thrust belt in the Lhozag-Cuona area of the eastern Himalayan orogen. The ∼4 km-thick THD is characterized by a top-to-south shear sense, moderate T/P Barrovian to high T/P Buchan type metamorphism and Eocene-Miocene partial melting. Zircon U-Pb dating of metasedimentary rocks and granitic gneisses from the THD yields protolith ages of the Late Cambrian to Early Ordovician. Based on structural analysis, zircon U-Pb ages, monazite U-Pb ages and mica ⁴⁰Ar/³⁹Ar thermochronology, the THD was the boundary shear zone at the top of the Greater Himalayan Crystalline Complex (GHC) and accommodated the persistent north-south shortening in the Tethyan Himalayan Sequence (THS) from ∼50 Ma to 20–17 Ma. From ∼20–17 Ma, the top-to-north South Tibetan Detachment System (STDS) was predominantly activated to juxtapose the unmetamorphosed or low-grade THS over the GHC. This tectonic transition can be attributed to the roof collapse in the eastern Himalaya (younger than that of the central-western Himalaya), which triggered rapid exhumation of the GHC and the northern Tethyan Himalayan gneiss domes. Hence, the THD was the predecessor of the STDS and a prolonged pathway for leucogranitic melts from the Eocene to early Miocene. The transition from the THD-controlled crustal thickening in the Eocene and Oligocene to the STDS-controlled extrusion in the Miocene shed insights on a new synthesis of the tectonic wedging model for the Himalayan evolution.

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引用次数: 0

Crustal silica content of East China: A seismological perspective and its significance 华东地壳硅含量：地震学视角及其意义

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-11-06 DOI: 10.1016/j.tecto.2024.230554

Ziwen Bao , Xiaohui Yuan , Wei Li , Yuan Gao , Xianliang Huang , Dequan Hong , Hongyu Ni

East China has experienced multiple periods of tectonic movements, which have contributed to the composition and rheological properties of its present crust. Estimating the composition of the crust is crucial for understanding the tectonic processes. Based on the teleseismic receiver functions with data from the National Seismic Network of China, we applied the H-κ-c method to obtain the crustal bulk V_P/V_S ratio and to constrain the SiO₂ content in the crust. We estimated the SiO₂ content to range from 50.89 wt% to 73.51 wt%, with an average value of 65.87 wt%, indicating a predominant felsic composition of the East China's crust. Our study suggests that the North-South Gravity Lineament (NSGL) is an approximate delimitator of the felsic and mafic crust in East China, hinting at a widespread deficiency of mafic lower crust in the east of the NSGL. The mafic crust is extensively distributed in the Taihang orogenic region (TSR) and WuLingshan gravity gradient belts (WLG), particularly in the Datong volcanic area, which manifests the mantle materials intraplating. The scatteredly distributed mafic crust at the east of the NSGL is mainly concentrated in the southeast coast of China and in the intersection region of the Tanlu Fault (TLF) and Sulu region. In Sulu region, the TLF may primarily provide a channel for the thermal intrusion from the underlying mantle lithosphere, which has increased the mafic content. The Pacific/Philippine Sea plate subduction has triggered a significant amount of crust-mantle material exchange below southeast China that resulted in a high degree of mafic crustal composition.

华东地区经历了多个时期的构造运动，形成了现在的地壳成分和流变特性。估算地壳的组成对于了解构造过程至关重要。基于中国国家地震台网数据的远震接收函数，我们应用H-κ-c方法获得了地壳体积VP/VS比，并对地壳中的SiO2含量进行了约束。我们估计地壳中SiO2的含量范围为50.89 wt% 至 73.51 wt%，平均值为65.87 wt%，表明华东地壳的主要成分为熔岩。我们的研究表明，南北重力线是华东地区长岩地壳和黑云母地壳的近似分界线，暗示南北重力线以东地区普遍缺乏黑云母下地壳。黑云母地壳广泛分布于太行造山带和武陵山重力梯度带，特别是大同火山区，表现为地幔物质内镀。国家南极重力梯度带东侧零星分布的黑云母地壳主要集中在中国东南沿海和郯庐断裂（TLF）与苏禄地区的交汇区。在苏禄地区，郯庐断层可能主要为来自下伏地幔岩石圈的热侵入提供了通道，从而增加了岩浆岩的含量。太平洋/菲律宾海板块俯冲在中国东南部下方引发了大量的地壳-地幔物质交换，造成了高度的岩浆地壳成分。

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引用次数: 0

Geophysical characterization of an alkaline‑carbonatite complex using gravity and magnetic methods at Magnet Cove, Arkansas, USA 在美国阿肯色州磁湾使用重力和磁力方法确定碱性碳酸盐岩复合体的地球物理特征

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-11-02 DOI: 10.1016/j.tecto.2024.230545

Chelsea M. Amaral , Andrew P. Lamb , Gregory Dumond

The Magnet Cove alkaline‑carbonatite complex (MCC), located in the Ouachita Mountains of south-central Arkansas in the United States, hosts an extensive variety of rare rock types and critical mineral resources with physical properties (density and magnetization) that contrast significantly with the sedimentary rocks into which they have intruded. Newly acquired ground-based gravity and magnetic data were used to develop two-dimensional and three-dimensional geophysical models of the Cretaceous-aged Magnet Cove intrusive complex. The models reveal that the MCC: (1) widens out at middle crustal depths to as much 22 km across, and may reach a depth of 20 km; (2) has a total volume (exposed and subsurface) that may be over 800 km³; (3) is likely connected at depth to other intrusions in the Arkansas alkaline province; and (4) has a geometry that is aligned with pre-existing structures such as the Reelfoot rift and the Ouachita orogenic belt, some of which were likely structurally controlled by the Precambrian crystalline basement and the continent-ocean transition zone buried beneath the Ouachita orogen. For the first time, the magnetic models of the MCC account for the presence of strong remanent magnetization. This results in a geophysical workflow necessary to accurately interpret magnetic anomalies over the much larger Arkansas alkaline province, its geologic and structural framework, and critical mineral potential.

磁湾碱性碳酸盐岩复合体（MCC）位于美国阿肯色州中南部的瓦奇塔山脉，拥有种类繁多的稀有岩石类型和重要的矿产资源，其物理性质（密度和磁化率）与其侵入的沉积岩形成鲜明对比。新获得的地基重力和磁力数据被用于开发白垩纪时期磁湾侵入复合体的二维和三维地球物理模型。模型显示，磁性海湾侵入体(1) 在中地壳深度扩大到 22 千米宽，深度可能达到 20 千米；(2) 总体积（裸露和地下）可能超过 800 千立方米；(3) 在深度上可能与阿肯色碱性矿带的其他侵入体相连；(4) 其几何形状与里尔富特裂谷和瓦奇塔造山带等先前存在的构造相一致，其中一些构造可能受前寒武纪结晶基底和埋藏在瓦奇塔造山带下的大陆-海洋过渡带的结构控制。MCC 的磁性模型首次考虑到了强剩磁的存在。这就产生了一个地球物理工作流程，它是准确解释更大的阿肯色碱性省的磁异常、其地质和结构框架以及关键矿产潜力所必需的。

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引用次数: 0

Subsurface basement structures of the Usangu basin, East African rift system, with implications for basin structural configuration and hydrocarbon potential 东非裂谷系统乌桑古盆地的地下基底结构及其对盆地结构构造和油气潜力的影响

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-10-26 DOI: 10.1016/j.tecto.2024.230544

Edward Pastory , Gabriel D. Mulibo , Isaac M. Marobhe

The Usangu basin is a rift basin developed along the Eastern arm of the East African rift system trending in the NE-SW direction. Although the general structures of the basin have been well studied, the structural configuration of the basin and the spatial and depth variations of sediment thickness are still not well known. This study investigates the structures related basement configuration and the variation of sediment thickness within the basin using the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM), aeromagnetic and gravity data. Results from DEM data indicate a few lineaments on the basin flanks representing the Usangu and Chimala border faults with no structures in the central part of the basin. The aeromagnetic and gravity data highlight three sets of normal and strike-slip faults, most of which trend NE-SW and others NNE-SSW, while a few trends WNW-ESE or NW-SE. Structures on the southwest of the basin reveal complex patterns attributed to the concentration of important tectonic and seismic activities in the study area. The Euler deconvolution and gravity models used to calculate the depth to the basement show that the basement is shallow in the north and south to southwest, and the basin deepens in the northeastern, northwestern and western parts. The findings also reveal that the basin has two grabens, troughs, depression and intrabasinal basement trending in the same direction as the basin configuration. The general thickness of sediments filling the basin ranges from 3 to 4.5 km, with the maximum accumulation of sediments reaching up to 4.8 km in the two depocenters at the south and southwest of the basin. The depth range of the sediments obtained implies that the basin has potential for hydrocarbon exploration with the possibility of natural gas occurrence.

乌桑古盆地是一个裂谷盆地，沿东非裂谷系统东臂发育，呈东北-西南走向。虽然对该盆地的总体结构已有深入研究，但对盆地的结构构造以及沉积厚度的空间和深度变化仍不甚了解。本研究利用航天飞机雷达地形图任务（SRTM）数字高程模型（DEM）、航空磁力和重力数据，对盆地内与基底构造相关的结构和沉积厚度变化进行了研究。数字高程模型数据结果表明，盆地两侧有几条代表乌桑古断层和奇马拉边界断层的线状构造，盆地中部没有构造。气磁和重力数据突出显示了三组正断层和走向滑动断层，其中大部分呈东北-西南走向，其他呈东北-西南走向，少数呈西北-东南走向或西北-东南走向。盆地西南部的构造显示出复杂的模式，这归因于研究区域集中了重要的构造和地震活动。用于计算基底深度的欧拉解卷积和重力模型显示，基底在北部和南部至西南部较浅，盆地在东北部、西北部和西部加深。研究结果还显示，盆地内有两个地堑、地槽、洼地和盆地内基底，其走向与盆地构造一致。充填盆地的沉积物一般厚度为 3 至 4.5 千米，在盆地南部和西南部的两个沉积中心，沉积物的最大堆积厚度达 4.8 千米。所获得的沉积物深度范围意味着该盆地具有油气勘探的潜力，有可能出现天然气。

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引用次数: 0

When did the Dead Sea fault become a transform? 死海断层是何时形成的？

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2024-10-25 DOI: 10.1016/j.tecto.2024.230543

Amit Segev , Nadav Wetzler , Uri Schattner

This study re-evaluates the ∼20 Myr development of the Dead Sea Fault System (DSFS) and its tectonic definition as a transform plate boundary. The DSFS conveys sinistral displacement between the Arabian-Sinai plates: ∼105 km along its ∼400 km-long southern segment (Gulf of Aqaba-Eilat to the Hula basin); ∼90 km and 4–16 km along the central and northern segments (∼190 km long each, across Lebanon, western Syria, and southern Turkey). A review of previous studies, combined with new seismological data analysis, associates the northward displacement decline with obstacles along the DSFS propagation path. During the Miocene, DSFS propagated up to the NW-trending Irbid rift (1st obstacle) and splayed NW towards the Mediterranean and NE along the Late Cretaceous Palmyra fold-thrust belt (2nd obstacle). Its reactivation uplifted the Hermon and the Anti-Lebanon mountain ranges. Northward DSFS propagation into the cold and rigid Aleppo plateau lithosphere (3rd obstacle) was stalled until the early Pliocene (∼5 Ma), when volcanism and ongoing regional tectonic forcing enabled the DSFS to shift to the Yammouneh fault and rupture through the Missyaf-Ghab branch farther north (central and northern segments, respectively). During the Pleistocene-recent, connection of the DSFS with the ophiolite belt and East Anatolian Fault System (EAFS) along the Bitlis suture zone (4th obstacle) has not yet been established. Seismological data show a clear separation between the EAFS and the DSFS, while seismicity is scattered across the Aleppo plateau and the central and northern DSFS segments. In contrast, seismicity is localized along the southern DSFS segment. Our findings suggest that, at present, the DSFS has still not made a structural, seismologic, and tectonic connection with the EAFS. Hence, we redefine the DSFS as a pre-transform and suggest its interaction with the EAFS is a world-class example of a fault-fault-fault triple junction in the making.

本研究重新评估了死海断裂系统（DSFS）20∼Myr的发展及其作为板块转换边界的构造定义。死海断裂系统传达了阿拉伯-西奈板块之间的正弦位移：沿其长达 400 公里的南段（亚喀巴湾-埃拉特到胡拉盆地）有 105 公里；沿中部和北部（各长 190 公里，横跨黎巴嫩、叙利亚西部和土耳其南部）有 90 公里和 4-16 公里。对以往研究的回顾，结合新的地震数据分析，将向北位移的下降与 DSFS 传播路径上的障碍联系起来。在中新世时期，DSFS 传播到西北走向的伊尔比德裂谷（第一道障碍），并向西北向地中海延伸，沿晚白垩世帕尔米拉褶皱推覆带向东北延伸（第二道障碍）。它的重新激活抬升了赫尔蒙和反黎巴嫩山脉。直到上新世早期（∼5 Ma），火山活动和持续的区域构造作用使得DSFS转移到Yammouneh断层，并在更北的Missyaf-Ghab分支断裂（分别为中部和北部地段）。在更新世晚期，DSFS 与蛇绿混杂岩带和东安纳托利亚断层系统（East Anatolian Fault System，EAFS）沿比特利斯缝合带（第 4 个障碍）的联系尚未确定。地震学数据显示，东安纳托利亚断裂带与东安纳托利亚断裂系统之间有明显的分隔，而地震活动则分散在阿勒颇高原以及东安纳托利亚断裂系统的中部和北部地段。相比之下，地震活动则集中在 DSFS 南部地段。我们的研究结果表明，目前，DSFS 仍未与 EAFS 在结构、地震学和构造上建立联系。因此，我们将 DSFS 重新定义为转型前，并认为其与 EAFS 的相互作用是正在形成的断层-断层-断层三重交界的世界级范例。

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引用次数: 0