大巴山西段高川地体构造变形特征及其意义   总被引：1，自引：0，他引：1  

胡健民董树文  孟庆任 《地质通报》2008,27(12)

勉略缝合带华北与华南大陆于印支期完成拼合的主要拼接带,在中国大陆的形成与演化中占据重要地位。但是,勉略带的东、西延伸,至今没有确定的结论,尤其陕西省勉县以东到湖北随州一带,还没有找到确凿的缝合带的证据。现今一些重要的文章多认为勉略带在勉县以东到达宁陕县两河口之后向南转折,沿着高川岩片的位置顺大巴山弧形构造带向东延伸到湖北随州一带。然而,本文的研究表明,高川岩片是一个独立于大巴山构造带的外来地质体,并称之为高川地体。高川地体是一个由近南北向右行走滑断层与轴向近南北向的走滑剪切褶皱构造组成的右行走滑构造系统,作者认为,它是大巴山冲断推覆构造向南推覆过程中,被从原勉略缝合带中挤过来的一片,它仅仅是被挟持在大巴山冲断—推覆构造带与大巴山前陆构造带之间的地壳浅层地质体,高川地体现在的位置不能代表勉略带向东的延伸。因此,大巴山弧形构造带也不是中国南北大陆最终碰撞拼贴的位置  相似文献   

塔河油田2区三叠系油藏类型初步探讨     

康立功 《安徽地质》2008,18(1):20-26

塔河油田2区三叠系油藏是西北分公司开发较早的碎屑岩油藏之一,开发层系有上油组、中油组,油柱高度在15～20m,储层为辫状三角洲相辫状三角洲前缘亚相水下分流河道、河口坝、分流间湾微相沉积,非均质性严重。本区上油组砂体厚度40～0m,中油组25～35m,分布较稳定,物性为中孔、中高渗储层,原油属低粘度轻质油。但2区三叠系油藏实钻变化大,见水快、产量递减快、含水上升快、采出程度低,开发效果较差,经过多次调整虽有一定程度改善,仍存在一些问题。本文认为2区三叠系油藏开发效果较差的原因之一是对本区油藏类型的认识上存在问题即2区三叠系油藏是以断裂控制的断块油藏而非背斜油藏,并延伸分析正在投入开发评价的S96-T901井区、TK232-T453井区及T206-T208井区等都为断块（断背斜）油藏。应用断块油藏的观点对塔河地区三叠系油藏勘探开发有重要指导意义。  相似文献   

南海海盆区莫霍面分布规律及其对深部钻探的意义     

秦绪文  张宝金  赵斌  路允乾  陈玺  王利杰  许振强  张如伟  耿明会  杨振  李建平  吕文超  尉建功 《地质学报》2022,96(8):2635-2646

钻遇莫霍面是人类一直以来的梦想。深海海底是地球上离莫霍面最近的地方，目前有研究推测南海是世界上莫霍面深度最浅的海域之一，但缺乏足够的直接证据。深反射地震探测可以直接揭示岩石圈的构造形态，是莫霍面探测的重要手段。本文基于长达15000 km的深反射多道地震剖面的解释、处理、制图和分析，结合前人的研究，形成了南海海盆区莫霍面反射特征和空间分布的初步认识。① 南海东部次海盆南部早期经历了较快速扩张，岩浆供应充足，受扩张停止后岩浆活动影响较小，基底平坦，地质构造相对简单，同时洋壳地震速度结构不存在异常，且有较强的广角莫霍面反射波和可识别的地幔顶部折射波，具备莫霍面钻探的基本条件。② 南海海盆不同区域的莫霍面反射强度存在较大差异。其中东部次海盆莫霍面反射最为强烈且清晰，西北次海盆次之，西南次海盆仅有零星出现的清晰莫霍面反射且可信度不高。③ 识别南海海盆区莫霍面地震反射长度超过3500 km，首次形成了海盆区深度域莫霍面地震反射空间分布图。与重力反演的莫霍面深度相比，利用深反射多道地震计算的莫霍面深度细节更为丰富，并且可以在垂向上清晰刻画莫霍面的结构。整体上，南海海盆区莫霍面地震反射强烈和可信度高的区域中，深度较浅的区域之一是东部次海盆南部，最浅处仅约9. 5 km，其中水深4. 01 km，洋壳厚度仅5. 54 km。综合判断，东部次海盆南部是南海重要的莫霍面钻探备选区，这对南海莫霍面钻探选址具有重要意义。  相似文献   

The Cauvery Shear Zone, Southern Granulite Terrain, India: A crustal-scale flower structure   总被引：2，自引：1，他引：2  

T.R.K. Chetty  Y.J. Bhaskar Rao 《Gondwana Research》2006,10(1-2):77

The Cauvery Shear Zone (CSZ) is a crustal-scale shear system within the Southern Granulite Terrain along the southern margin of the Archaean Dharwar craton. Structural interpretation of satellite data and field observations reveal four major shear zones within the CSZ system. They show dextral shear kinematics synchronous with a major Neoproterozoic tectono-metamorphic event (D2) associated with intracrustal melting and migmatisation. The disposition, geometry and contemporaneity of shear fabrics of the CSZ system are modelled in terms of a crustal-scale flower structure akin to transpressional and collisional orogens. In the light of recent seismic evidence for a displaced Moho structure and a mid- to lower-crustal low velocity zone, the flower structure across the CSZ may extend to mantle depths.  相似文献   

HP–LT Variscan metamorphism in the Cubito-Moura schists (Ossa-Morena Zone, southern Iberia)     

Guillermo Booth-Rea  Jos Fernando Simancas  Antonio Azor  Jos Miguel Azan  Francisco Gonzlez-Lodeiro  Paulo Fonseca 《Comptes Rendus Geoscience》2006,338(16):1260-1267

Multi-equilibrium thermobarometry shows that low-grade metapelites (Cubito-Moura schists) from the Ossa–Morena Zone underwent HP–LT metamorphism from 340–370 °C at 1.0–0.9 GPa to 400–450 °C at 0.8–0.7 GPa. These HP–LT equilibriums were reached by parageneses including white K mica, chlorite and chloritoid, which define the earliest schistosity (S₁) in these rocks. The main foliation in the schists is a crenulation cleavage (S₂), which developed during decompression from 0.8–0.7 to 0.4–0.3 GPa at increasing temperatures from 400–450 °C to 440–465 °C. Fe³⁺ in chlorite decreased greatly during prograde metamorphism from molar fractions of 0.4 determined in syn-S₁ chlorites down to 0.1 in syn-S₂ chlorites. These new data add to previous findings of eclogites in the Moura schists indicating that a pile of allochtonous rocks situated next to the Beja-Acebuches oceanic amphibolites underwent HP–LT metamorphism during the Variscan orogeny. To cite this article: G. Booth-Rea et al., C. R. Geoscience 338 (2006).  相似文献   

The Tornquist Zone, a north east inclining lithospheric transition at the south western margin of the Baltic Shield: Revealed through a nonlinear teleseismic tomographic inversion     

P. Voss  K. Mosegaard  S. Gregersen  TOR Working Group 《Tectonophysics》2006,416(1-4):151

From July 1996 to August 1997 the TOR project operated 130 seismographs in North Germany, Denmark and South Sweden, with the aim of collecting signals from local, regional and teleseismic earthquakes. This data set is particularly interesting since the seismic antenna crosses the most significant geological boundary in Europe, the Tornquist Zone, which in the northern part is the border between the Baltic Shield and the younger European lithosphere. Previous studies have shown significant physical changes in the crust and upper mantle across this transition zone, including two independent teleseismic tomographic studies of the TOR data set. But these two studies disagree on the orientation of the slope of the transition. Both studies used an iterative linearized inversion method. We will in this work Preprint submitted to Elsevier Science 27 July 2005 present an inversion based on Bayesian statistics, where the solution space is examined in order to study a very large number of tomographic solutions and to examine the solution uniqueness and uncertainty. The method is applied to measurements of 3345 relative teleseismic P-phase travel times from 48 teleseismic earthquakes with good azimuthal coverage with respect to the great circle arc of the TOR array. We find the lithospheric transition to be a north east inclination of around 30° to 45° off vertical.  相似文献   

Anticlockwise evolution of ultrahigh-temperature granulites within continental collision zone in southern India   总被引：2，自引：0，他引：2  

M. Santosh  K. Sajeev   《Lithos》2006,92(3-4):447-464

We report three new localities of corundum and sapphirine-bearing hyper aluminous Mg-rich and silica-poor ultrahigh-temperature granulites formed during Late Neoproterozoic-Cambrian times within the Palghat–Cauvery Shear Zone system in southern India. From petrologic characteristics, mineral chemistry and petrogenetic grid considerations, the peak metamorphic conditions of these rocks are inferred to lie around 950–1000 °C (as suggested by Al in orthopyroxene thermometer) at pressures above 10 kbar (as indicated by the equilibrium orthopyroxene–sillimanite–gedrite ± quartz assemblage). These rocks preserve several remarkable reaction textures, the most prominent among which is the triple corona of spinel–sapphirine–cordierite on corundum, with the whole textural assembly embedded within the matrix of gedrite, suggesting the reaction: Ged + Crn = Spl + Spr + Crd. The formation of sapphirine–sillimanite assemblage/symplectite associated with relict corundum and porphyroblasitc cordierite is explained by the reaction: Crd + Crn = Spr + Sil. The association of sapphirine cordierite symplectite with gedrite–sillimanite assemblage as well as with aluminosilicate boundaries indicates the gedrite consuming reaction: Ged + Sil = Spr + Crd. Extensive growth of sapphirine–cordierite observed on the rim of gedrite porphyroblasts with spinel occurring as relict inclusions within the sapphirine indicates the reaction: Ged + Spl = Spr + Crd. The pressure–temperature (P–T) path defined from the observed mineral assemblages and reaction texture is characterized by anticlockwise trajectory, with a prograde segment of initial heating and subsequent deep burial, followed by retrograde near-isothermal decompression. Such an anticlockwise trajectory is being reported for the first time from southern India and has important tectonic implications since these rocks were developed at the leading edge of the crustal block that was involved in collisional orogeny and subsequent extension during the final phase of assembly of the Gondwana supercontinent. We propose that the rocks were subjected to deep subduction and rapid exhumation, and the extreme thermal conditions were attained either through input from underplated mantle-derived magmas, or convective thinning or detachment of the lithospheric thermal boundary layer during or after crustal thickening.  相似文献   

Crust and upper mantle structure of a continental backarc: central North Island, New Zealand   总被引：3，自引：0，他引：3  

W. R. Stratford  T. A. Stern 《Geophysical Journal International》2006,166(1):469-484

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A N–S receiver function profile across the Variscides and Caledonides in SW Ireland     

Michael Landes  J. R. R. Ritter  B. M. O'Reilly  P. W. Readman  V. C. Do 《Geophysical Journal International》2006,166(2):814-824

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Lithospheric structure of an active backarc basin: the Taupo Volcanic Zone, New Zealand   总被引：3，自引：0，他引：3  

Antony Harrison  Robert S. White 《Geophysical Journal International》2006,167(2):968-990

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