On the Morphological Complexity of the Graptolite Tubaria in the Darriwilian(Middle Ordovician)     

MA Xuan  ZHANG Yuandong 《《地质学报》英文版》2019,93(Z1):135-137

正1 Introduction As one of the major zooplanktonic organisms in the Ordovician and Silurian marine ecosystems,graptolites played a unique role in the GOBE (Great Ordovician Biodiversification Event) and underwent a considerable variation of diversities both in lifestyle and in speciation through the Ordovician (Sadler et al.,2011;Cooper et al.,2014).Graptolites are among the early  相似文献   

SHRIMP Zircon U-Pb Ages of the Wajilitag Igneous Complex: Constraints on the Origin of A-type Granitoids in the Tarim Large Igneous Province, NW China     

CAO Jun  TAO Jihu  WANG Xuan 《《地质学报》英文版》2017,91(6):2318-2320

<正>Objective Large igneous provinces(LIPs)are sites of spatially contiguous,rapidly emplaced magmatic rocks,which represent the physical and chemical transfer of material from the mantle to the crust.Exposed within some continental LIPs are felsic and mafic plutonic and volcanic rocks.Although their volumes are minor compared to the flood basalts,the plutonic rocks of continental LIPs are  相似文献   

Structural Evolution of the Eastern Qiulitagh Fold and Thrust Belt,Northern Tarim Basin,China   总被引：4，自引：3，他引：1  

YANG Minghui  JIN Zhijun  LU Xiuxiang  SUN Dongsheng  TANG Xuan  PENG Gengxin  LEI Ganglin 《《地质学报》英文版》2009,83(2):347-358

The eastern Qiulitagh fold and thrust belt (EQFTB) is part of the active Kuqa fold and thrust belts of the northern Tarim Basin. Seismic reflection profiles have been integrated with surface geologic and drill data to examine the deformation and structure style of the EQFTB, particularly the deformational history of the Dina 2 gas field. Seismic interpretations suggest that Dongqiu 8 is overall a duplex structure developed beneath a passive roof thrust, which generated from a tipline in the Miocene Jidike Formation, and the sole thrust was initiated from the same Jidike Formation evaporite zone that extends westward beneath the Kuqatawu anticline. Dongqiu 5 is a pop-up structure at the western part of the EQFTB, also developed beneath the Jidike Formation evaporite. Very gentle basement dip and steep dipping topographic slope in the EQFTB suggest that the Jidike Formation salt provides effective decoupling. The strong deformation in the EQFTB appears to have developed further south, in an area where evaporite may be lacking. Since the Pliocene, the EQFTB has moved farther south over the evaporite and reached the Yaken area. Restoring a balanced cross-section suggests that the minimum shortening across the EQFTB is more than 7800 m. Assuming that this shortening occurred during the 5.3 Ma timespan, the shortening rate is approximately 1.47 mm/year.  相似文献   

泰国、老挝南部和越南中部的非海相白垩纪双壳类生物地层学     

沙金庚  Assanee MEESOOK  Xuan Khien NGUYEN 《地层学杂志》2012,(2):382-399

泰国、老挝和越南白垩纪沉积全属非海相,它们广泛分布于泰国北部、东北部、西南部和南部,老挝北部、中部和南部,越南东北部、西北部、中部和南部。泰国南部的白垩纪地层分为Lam Thap,Sam Chom和Phun Phin组;其他地区,特别是西北部的呵叻高原地区的白垩系属呵叻群的Phra Wihan,Sao Khua,Phu Phan,Khok Kruat,Maha Sarakham及Phu Thok组。在老挝,万象盆地的白垩系由老挝呵叻群的NamSet,Phu Phanang,Ban Ang,Champa和Ban Thalat组与丰洪群的Thangon和Saysomboun组组成;沙湾拿吉(东兴)盆地的白垩系由南通(河)群的Nam Phouan,Nam Xot,Nam Noy和Nong Boua组组成。越南的白垩系在西北部分为Nam Na,Yen Chau,Van Chan和Ngoi Thia组,东北部为Ban Hang组,中部分为NhaTrang,Mu Gia和Dong Dzuong组,南部则为Phu Quoc组。三国白垩系的岩性普遍以红棕色至浅灰色砂岩、砾(岩质)砂岩、粉砂岩、泥岩和砾岩为主。泥岩中具有钙质结核和硅结砾岩,但盐和石膏仅见于Maha Sarakham,Saysomboun和Yen Chau组内。过去,这些白垩纪地层的生物地层没有经过详细研究。根据地层层序和化石对比,在泰国东北部呵叻高原和南部半岛地区及老挝南部沙湾拿吉(东兴)盆地中识别出了2个标记非海相白垩纪的类三角蚌类化石组合:阿普特期(但可上延至阿尔必期)的Trigonioides(Trigonioides)kobayashi-Plicatounio(Guangxiconcha)suzukii组合,阿普特阿尔必期(但主要为阿尔必期)的Trigonioides(Diversitrigonioides)diversicostatus-Pseudohyria subovalis组合。越南中部可能也产早白垩世阿普特阿尔必期的类三角蚌类双壳类Plisatouniosp.-Trigonioidessp.组合。通过双壳类组合,并结合包括孢粉和恐龙在内的其他化石的对比,泰国北部和南部、老挝南部和越南中部的非海相白垩纪地层得到了定年和对比,从而揭示了东南亚非海相白垩纪盆地的演化历史。  相似文献   

Subsurface target recognition in Utopia Planitia of Mars by Tianwen-1 FP-SPR simulation     

WANG Ying  FENG Xuan  LIANG Wenjing  LI Xiaotian  XUE Cewen 《世界地质(英文版)》2021,24(3):169-176

As a cold and dry planet, Mars contains water resources in the form of water ice, so that the electromagnetic waves can be transmitted to the deep underground to get the information of the topography and subsurface geological structure. Subsurface penetrating radar(SPR) can be widely used in deep space exploration for a long time because of its non-destructive detection mode and its working characteristics not limited by visible light. It is an important type of equipment for detecting the subsurface structure of planets. Orbiter radar is mainly used in Mars exploration. However, because of its low resolution, it is difficult to describe the near surface structure, so there is a lack of radar data which can reflect the shallow information. In this paper, a three-dimensional near surface model of Utopia Planitia on Mars is established. In order to make the simulation results more reasonable, the key factors such as topographic relief, subsurface rocks and water ice, and the variation of dielectric constant in different layers are taken into account. Then the full polarization forward modeling is carried out by using the three-dimensional finite-difference time-domain method. The acquired full polarimetric subsurface penetrating radar(FP-SPR) data with noise is preprocessed and further processed by Pauli decomposition. The underground reflection can be picked up more clearly from the Pauli decomposition results. This work is helpful to identify more details of subsurface structures and provides a reference for the measured data in the future.  相似文献   

Systematic Studies of Dynamic Triggering in Continental China     

PENG Zhigang  WANG Weijun  WU Chunquan  GONG Xuan  WU Jing  CHEN Qi-Fu 《地质学报》2013,87(Z1):51-52

  相似文献   

The Early Permian Woniusi Flood Basalts from the Baoshan Terrane, SW China: Petrogenesis and Geodynamic Implications     

CAO Jun  ZHANG Gaizhi  WANG Xuan  CHEN Jun 《《地质学报》英文版》2020,94(6):2091-2114

The Woniusi flood basalts from the Baoshan terrane, SW China, represent a signi?cant eruption of volcanic rocks which were linked to the Late Paleozoic rifting of the Cimmeria from the northern margin of East Gondwana. However, the precise mechanism for the formation and propagation of the rifting is still in debate. Here we report 40Ar/39Ar dating, whole-rock geochemistry, and Sr–Nd–Pb isotopes for the Woniusi basalts from the Baoshan terrane of SW China, with the aim of assessing if a mantle plume was related to the formation of the continent Cimmeria. 40Ar/39Ar dating of the Woniusi basalts yielded ages of 279.3 ± 1.1 Ma and 273.9 ± 1.5 Ma, indicating they were emplaced during the Early Permian. Whole-rock geochemistry shows that these basalts have subalkaline tholeiitic af?nity, low TiO2 (1.2–2.2 wt%), and fractionated chondrite-normalized LREE and nearly ?at HREE patterns [(La/Yb)N = 2.86–5.77; (Dy/Yb)N = 1.21–1.49] with noticeable negative Nb and Ta anomalies on the primitive mantle-normalized trace element diagram. The ?Nd(t) values (?4.76 to +0.92) and high (206Pb/204Pb)i (18.40?18.66) along with partial melt modeling indicates that the basalts were likely derived from a sub-continental lithospheric mantle (SCLM) source metasomatized by subduction-related processes. On the basis of a similar emplacement age to the Panjal basalts and Qiangtang mafic dykes and flood basalts in the Himalayas, combined with a tectonic reconstruction of Gondwana in the Early Permian, we propose that the large-scale eruption of these basalts and dykes was related to an Early Permian mantle plume that possibly initiated the rifting on the northern margin of East Gondwana.  相似文献   

Impact of Perturbation Schemes on the Ensemble Prediction in a Coupled Lorenz Model     

Qian ZOU  Quanjia ZHONG  Jiangyu MAO  Ruiqiang DING  Deyu LU  Jianping LI  Xuan LI 《大气科学进展》2023,40(3):501-513

Based on a simple coupled Lorenz model, we investigate how to assess a suitable initial perturbation scheme for ensemble forecasting in a multiscale system involving slow dynamics and fast dynamics. Four initial perturbation approaches are used in the ensemble forecasting experiments: the random perturbation(RP), the bred vector(BV), the ensemble transform Kalman filter(ETKF), and the nonlinear local Lyapunov vector(NLLV) methods. Results show that,regardless of the method used, the ensemble ave...  相似文献   

A simulation experiment on the GM estimation for Comet 133P/Elst-Pizarro     

Wu-Tong Gao  Jian-Guo Yan  Wei-Tong Jin  Xuan Yang  Chen Yang  Mao Ye  Fei Li  Jean-Pierre Barriot 《天文和天体物理学研究(英文版)》2021,(1)

In China’s asteroid mission to be launched around 2025,(7968)133 P/Elst-Pizarro(hereafter 133 P)will be the second target,after a visit to asteroid(469219)Kamo’oalewa.This paper describes a simulation of precise orbit determination for the spacecraft around comet 133 P,as well as estimation of its gravitational parameter(GM)value and the solar radiation pressure coefficient Cr for the spacecraft.Different cometocentric distances of 200,150 and 100 km orbits are considered,as well as two tracking modes:exclusive two-way range-rate mode(Earth station to spacecraft)and combinations of two-way range-rate and local spacecraft onboard ranging to the comet.Compared to exclusive two-way range-rate,the introduction of local ranging observables improves the final GM uncertainties by up to one order of magnitude.An ephemeris error in the orbit of 133 P is also considered,and we show that,to obtain a reliable estimate of the GM for 133 P,this error cannot exceed a one km range.  相似文献   

大火成岩省及其在古大陆重建及裂解研究中的应用     

张拴宏  赵越  裴军令  王宏宇  胡国辉  张琪琪  蔡瑜杭  孔令昊  王森  王开 《地质论评》2022,68(4):2022072011-2022072011

大火成岩省是地质历史上与地球深部过程（如地幔柱）密切相关的极端地质事件,以相对较短时期内形成规模宏大的板内幔源基性岩浆活动为主要特征,对研究全球性大气—海洋环境的巨变与生物灭绝、大规模成矿及超大陆的重建和裂解均有重要意义。从潘吉亚超大陆的裂解过程可以看出,尽管不是所有的大火成岩省都与大陆裂解有关,但几乎每一次重要的裂解事件都伴有大火成岩省的出现,因此大火成岩省对于研究前潘吉亚超大陆,特别是对于缺少古生物等重建标志,古地磁数据偏少的前寒武纪超大陆重建及裂解研究有重要价值。近20多年来随着年代学技术的进步及研究工作的不断深入,大火成岩省在古大陆重建及裂解方面取得了一些重要进展,并发挥了越来越重要的作用。前寒武纪大火成岩省由于经历了多次裂解事件改造及后期抬升剥蚀或覆盖的影响,现今保留的是一些分散在不同大陆上的大火成岩省残片或碎片。用大火成岩省开展古大陆重建及裂解的目标就是通过不同陆块大火成岩省或大规模基性岩浆活动的年代学、岩石学及地球化学对比,结合其他证据,恢复大火成岩省形成时的时空分布特征,据此来确定这些陆块在超大陆中的相对或绝对位置。与其他前寒武纪大陆重建标志相似,大火成岩省也有一些局限性及不确定性,因此应用大火成岩省开展古大陆重建及裂解研究中要与前岩浆期沉积地层中的特殊事件层（如冰碛岩、火山灰、黑色页岩、不整合面、古生物等）对比、岩墙几何学产状、基性岩浆事件序列对比、古地磁、大型构造（如造山带）对比及深部地球物理等多学科方法相结合。  相似文献