地表剥蚀、下地壳流变与造山作用研究进展   总被引：2，自引：0，他引：2  

张新钰  季建清  韩宝福  陈建军  余绍立 《地球科学进展》2006,21(5):521-531

岩石圈的流变特性研究已经成为固体地球科学研究中的重要领域,是地球科学新理论、新观点的重要渊源。最近的研究表明,下地壳普遍存在的韧性流是造山作用的重要制约因素。在下地壳物质层流变作用机制的调节下,地表剥蚀作用并不仅仅是传统意义上地表夷平的因素,它还能打破地壳动力学和热力学平衡,引起地壳内物质和结构的重置,进而促成山脉的加剧隆升;地表剥蚀作用的强度既受控于造山带的抬升,也受制于地球外圈层(大气圈、水圈、生物圈)。以天山山脉和喜马拉雅山山脉的隆起、喜马拉雅山山脉的变质作用以及相关的构造活动为例,说明在造山过程中,尽管传统意义上的造山作用与地球内部动力过程,即构造作用有密切联系,但是与构造运动的时空尺度不同,地表剥蚀作用也能够在相对较小的时空尺度内,通过影响和控制造山带下地壳的韧性流动,成为地壳抬升和造山带构造演化的重要动力因素。对地壳的流变特性和变质变形研究是当前地球系统科学研究的一个重要切入点。  相似文献   

Changes in Relative Plate Motion during the Isan Orogeny (1670-1500 Ma) and Implications for Pre-Rodinia Reconstructions     

A. S. A. A. ABU SHARIB 《《地质学报》英文版》2016,90(1):88-105

Foliation inflexion/intersection axes(FIAs)preserved within porphyroblasts that grew throughout Isan orogenesis reveal significant anticlockwise changes in the direction of bulk horizontal shortening between 1670 and 1500 Ma from NE-SW,N-S,E-W to NW-SE.This implies an anticlockwise shift in relative plate motion with time during the Isan orogeny.Dating monazite grains amongst the axial planar foliations defining three of the four FIAs enabled an age for the periods of relative plate motion that produced these structures to be determined.Averaging the ages from monazite grains defining each FIA set revealed 1649±12 Ma for NE-SW shortening,1645±7 Ma for N-S shortening,and 1591±10 Ma for that directed E-W.Inclusion trail asymmetries indicate shear senses of top to the SW for NW-SE FIAs and dominantly top to the N for E-W FIAs,reflecting thrusting towards the SW and N.No evidence for tectonism related to early NE-SW bulk horizontal shortening has previously been detected in the Mount Isa Inlier.Amalgamation of the Broken Hill and possibly the Gawler provinces with the Mount Isa province may have taken place during these periods of NE-SW and N-S-directed thrusting as the ages of tectonism are similar.Overlapping dates,tectonic,metamorphic,and metallogenic similarities between eastern Australia(Mount Isa and Broken Hill terranes)and the southwest part of Laurentia imply a most probable connection between both continental masses.Putting Australia in such position with respect to North America during the Late-Paleo-to-Mesoproterozoic time is consistent with the AUSWUS model of the Rodinia supercontinent.  相似文献   

Palaeozoic suturing of eastern and western Tasmania in the west Tamar region: Implications for the tectonic evolution of southeast Australia     

A. R. Reed  C. Calver  R. S. Bottrill 《Australian Journal of Earth Sciences》2013,60(5):809-830

A new tectonic model for Tasmania incorporates subduction at the boundary between eastern and western Tasmania. This model integrates thin‐ and thick‐skinned tectonics, providing a mechanism for emplacement of allochthonous elements on to both eastern and western Tasmania as well as rapid burial, metamorphism and exhumation of high‐pressure metamorphic rocks. The west Tamar region in northern Tasmania lies at the boundary between eastern and western Tasmania. Here, rocks in the Port Sorell Formation were metamorphosed at high pressures (700–1400 MPa) and temperatures (400–500°C), indicating subduction to depths of up to 30 km. The eastern boundary of the Port Sorell Formation with mafic‐ultramafic rocks of the Andersons Creek Ultramafic Complex is hidden beneath allochthonous ?Mesoproterozoic turbidites of the Badger Head Group. At depth, this boundary coincides with the inferred boundary between eastern and western Tasmania, imaged in seismic data as a series of east‐dipping reflections. The Andersons Creek Ultramafic Complex was previously thought of as allochthonous, based mainly on associations with other mafic‐ultramafic complexes in western Tasmania. However, the base of the Andersons Creek Ultramafic Complex is not exposed and, given its position east of the boundary with western Tasmania, it is equally likely that it represents the exposed western edge of autochthonous eastern Tasmanian basement. A thin sliver of faulted and metamorphosed rock, including amphibolites, partially separates the Badger Head Group from the Andersons Creek Ultramafic Complex. Mafic rocks in this package match geochemically mafic rocks in the Port Sorell Formation. This match is consistent with two structural events in the Badger Head Group showing tectonic transport of the group from the west during Cambrian Delamerian orogenesis. Rather than being subducted, emplacement of the Badger Head Group onto the Andersons Creek Ultramafic Complex indicates accretion of the Badger Head Group onto eastern Tasmania. Subsequent folding and thrusting in the west Tamar region also accompanied Devonian Tabberabberan orogenesis. Reversal from northeast to southwest tectonic vergence saw imbricate thrusting of Proterozoic and Palaeozoic strata, possibly coinciding with reactivation of the suture separating eastern and western Tasmania.  相似文献   

A tale of two synclines: Rifting,inversion and transpressional popouts at Lake Julius,northwestern Mt Isa terrane,Queensland     

G. S. Lister  M. G. O'Dea  I. Somaia 《Australian Journal of Earth Sciences》2013,60(2):233-250

This study reviews the origin of two approximately east‐west‐trending synclines in the Lake Julius area at the eastern edge of the Leichhardt Rift. The genesis of one of these structures can be found in a north‐south shortening event (D₁) that occurred at the beginning of the compressional Isan Orogeny (at ca 1600 Ma). Metasediments in a cross‐rift were rammed against a competent buttress defined by the pre‐existing rift architecture, producing the approximately east‐west‐trending Somaia Syncline and its associated axial‐plane slaty cleavage. In contrast, the Lake Julius Syncline was produced by reorientation of an originally approximately north‐south‐trending (D₂) fold, in a transpressional zone adjacent to a strike‐slip fault, at the end of the Isan orogeny. The effects of late fault movement can be partially reconstructed, based on correlations assuming that regionally developed trains of upright folds formed during the peak of the Isan Orogeny (D₂). These folds have been offset, as well as having been tightened and disrupted at the same time as fault movements took place. The overall pattern of movement in the Lake Julius region can be explained as the result of an ‘indentor’ ramming into the ancient edge of the Leichhardt Rift, which acted as a buttress.  相似文献   

Financial statement as at 31 December 1969     

N. G. Direen  A. J. Crawford 《Australian Journal of Earth Sciences》2013,60(4):491-502

The Tasman Line, a much‐discussed concept in the geology and tectonics of eastern Australia, has a long and chequered history of interpretation. This extends to current debates regarding the age and position of the Tasman Line in Gondwana‐Rodinia reconstructions. We present constraints, from mapping, geochemistry and geophysics, on the interpretation of gravity and magnetic lineaments attributed to the Tasman Line in New South Wales, South Australia, Victoria and Tasmania. These pieces of evidence suggest a protracted and complex latest Neoproterozoic to Carboniferous geological history that produces a variety of geophysical responses, rather than a simple ‘Line’. We also find no evidence of Rodinian breakup age activity responsible for any of the anomalies. In light of these findings, our preference is that the Tasman Line concept be abandoned as misleading, especially with regard to models of Rodinia‐Gondwana breakup, which must have occurred elsewhere, possibly well to the east. Instead, the rocks preserved in the westernmost part of the Tasmanides are consistent with previously proposed ‘Southwest Pacific’‐style models for Neoproterozoic continental breakup, margin formation and reaccretion of continental fragments in the Early Palaeozoic.  相似文献   

库车坳陷沉降与天山中新生代构造活动   总被引：13，自引：0，他引：13  

杨庚  钱祥麟 《新疆地质》1995,(3)

位于塔里木盆地北缘、天山南侧的库车坳陷为中新生代发育的构造单元。坳陷与天山造山带在成因上紧密相连，坳陷的沉降是由于天山山体隆升扩展引起的岩石圈挠曲响应。根据纵横向不同位置盆地沉降史的分析对比，该坳陷为典型的挤压盆地。推测中生代时期天山造山带以走滑和逆冲作用为主，新生代时期至少在库车坳陷北缘，天山造山带以向南冲断作用为主。库车坳陷强烈沉降时期并不对应于粗碎屑沉积，而对应于细碎屑沉积时期，即天山造山带构造强烈活动时期。天山造山带强烈活动造成库车坳陷强烈沉降，其主要原因与塔里木板块南侧的羌塘地体、拉萨地体、科西斯坦杂岩和印度次大陆的增生碰撞有关。  相似文献   

A Pan-African alkaline pluton intruding the Saramuj Conglomerate,south-west Jordan     

Ghaleb Jarrar  Horst Wachendorf  Dieter Zachmann 《International Journal of Earth Sciences》1993,82(1):121-135

The geological setting, petrography and bulk mineral chemistry of a monzodiorite and a presumably consanguineous megaporphyry with large (up to 25 cm) labradorite megacrysts, both intruding the upper Proterozoic Saramuj Conglomerate in south-west Jordan (south eastern shore of the Dead Sea), were examined. The crystallization temperatures of the monzodiorite and the megaporphyry as determined from pyroxene thermometry and supported by contact metamorphic mineralogy are about 700 and 900°C, respectively. The intrusion depth of the monzodiorite is about 3–4 km. The monzodiorite was emplaced in the Saramuj Conglomerate at about 595 + 2 Ma ago according to Rb/Sr and U/Pb age determinations.The stratigraphic positions of the monzodiorite, megaporphyry and their host rock (the Saramuj Conglomerate) were compared with time-equivalent lithologies in the Arabian-Nubian Shield. Correspondence to: H. Wachendorf  相似文献   

The refraction seismic experiment GRANU95 in the Saxothuringian belt, southeastern Germany   总被引：1，自引：0，他引：1  

Enderle  Schuster  Prodehl  Schulze  & Bribach 《Geophysical Journal International》1998,133(2):245-259

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庐山运动   总被引：1，自引：0，他引：1  

毕华  谭克仁 《矿物学报》1997,17(3):291-296

本文简述了庐山隆-滑构造的基本特征。在中元古代双桥山群底部的顺层韧变带中，把前人的断层构造砾或沉积成因的巨厚层状变质复成分砾岩，自上而下分离出三层砾：上部砾、中部砾、下部砾。其中上部砾为断层构造砾；中部砾不是砾，而是构造分泌物；下部砾为沉积底砾。在此基础上，同时参考研究区早元古代星子群与中元古代双桥山群构造、岩浆活动、变质作用等方面的差异，建立了“庐山运动”，其活动时间为2200～1800Ma，这可以与华北及华南其它地区同时期的构造运动相对比，但庐山运动的强度相对较弱，表现为以垂直隆升为特色的造陆运动，它曾使研究区早元古代晚期至少遭受过长达200Ma（1800～1600Ma）的风化、剥蚀作用。  相似文献   

泰国Khorat盆地二叠纪石灰岩的重磁化研究          下载免费PDF全文

杨振宇 《地球物理学报》1996,39(Z1):173-181

泰国Ｋｈｏｒａｔ盆地西部的晚二叠世石灰岩的古地磁研究表明磁铁矿为稳定剩磁的主要载体多组分磁分量分离技术揭示了高温磁组分（或高矫顽力）具有呈对分布的正、反极性．但是，应用逐渐展平岩层法可以发现各采样点的平均特征磁化方向在岩层展平至３０％时．磁化方向最为集中．这一发现表明二叠纪石灰岩中所揭示出的磁化方向很可能形成于褶皱（期）过程中．野外观察表明，二叠纪石灰岩在印支期发生强烈褶皱并被晚三叠世湖相石灰岩角度不整合覆盖．所以二叠纪石灰岩的重磁化很可能发生在中、晚三叠世的印支期．这些石灰岩样品切片后经显微镜、扫描电镜和电子探针分析，次生磁铁矿多数与方解石微晶和铁质碳酸钙粒共生，且多分布在方解石脉附近．重磁化很可能是由于印支期造山运动时，铁质碳酸钙受碳水化合物流体的蚀变作用所引起的。  相似文献