鄂尔多斯盆地多种能源矿产分布及其构造背景   总被引：9，自引：0，他引：9  

邓军  王庆飞  高帮飞  徐浩  周应华 《地球科学》2006,31(3):330-336

借助“成矿系统”的思维, 探讨鄂尔多斯盆地成矿(藏)系统形成机制及其构造背景.盆地于中生代处于大地构造体制转折的重要阶段, 盆地边缘的造山活动显著, 盆内亦分别于晚三叠世、晚侏罗世与晚白垩世左右发生过3次构造热事件.区域构造体制转换事件导致了多种成藏(矿)作用的发生.盆地内部的构造热事件引发了有机流体的活动, 周缘造山作用产生了向盆内流动的无机含铀热液.有机和无机流体的活动过程中存在相互作用, 有机流体的存在形成氧化-还原障, 导致无机流体关键物理化学参数的转变, 在氧化-还原界面处成矿.突变成矿和界面成矿是多种能源矿产成矿过程的主要机制.   相似文献   

江南隆起带皖赣相邻区燕山期岩浆岩 Nd-Sr同位素特征   总被引：12，自引：0，他引：12       下载免费PDF全文

袁峰  周涛发  范裕  岳书仓  朱光  侯明金 《地质科学》2006,41(1):133-142

江南隆起带皖南地区与赣东北地区燕山期岩浆岩Nd-Sr同位素特征的对比研究表明,皖南燕山期花岗岩体、斑岩体及赣东北燕山期花岗岩与赣东北燕山期斑岩体在成岩物质来源上具有明显差异。皖南燕山期花岗岩和斑岩体及赣东北燕山期花岗岩成岩物质以壳源为主,成岩物质来源区夹有一定的幔源物质,而赣东北燕山期斑岩体则具有幔源特征,这是赣东北地区燕山期与岩浆岩有关的多金属矿床发育、而皖南地区不发育的重要原因。Nd-Sr同位素的研究结果与地球物理、成岩构造背景和稀土元素等研究结果相吻合。  相似文献   

从洋-陆俯冲到陆-陆碰撞:回眸与展望   总被引：2，自引：0，他引：2  

许志琴  郑碧海  王勤 《地质学报》2021,95(1):75-97

大陆造山带的经典含义是指由于大陆地壳岩石在板块俯冲-碰撞的巨大挤压应力下,遭受强烈变形、变质和熔融作用,地壳发生大规模缩短、加厚和隆升而形成的地带.分布在大陆边缘和内部的造山带,经历从洋壳扩张、洋-陆俯冲到陆-陆碰撞的造山过程,形成"俯冲增生型"、"陆陆碰撞型"和远离板块边界的"陆内型"造山带.造山带类型的分析是识别地...  相似文献   

P–T–t–D records of Early Palaeozoic Andean-type shortening of a hot active margin: The Dunhuang block in NW China     

Jérémie Soldner  Pavla Štípská  Karel Schulmann  Chao Yuan  Robert Anczkiewicz  Yingde Jiang  Marta Koziarska  Le Zhang  Yunying Zhang  Xinyu Wang 《Journal of Metamorphic Geology》2023,41(1):59-96

High-pressure (HP) granulites form either in the domain of the subducted plate during continental collision or in supra-subduction systems where the thermally softened upper plate is shortened and thickened. Such a discrepancy in tectonic setting can be evaluated by metamorphic pressure–temperature–time-deformation (P–T–t–D) paths. In the current study, P–T–t–D paths of Early Palaeozoic HP granulite facies rocks, in the form of metabasic lenses enclosed in migmatitic metapelite, from the Dunhuang block, NW China, are investigated in order to constrain the nature of the HP rocks and shed light on the geodynamic evolution of a modern hot orogenic system in an active margin setting. The rocks show a polyphase evolution characterized by (1) relics of horizontal or gently dipping fabric (S1) preserved in cores of granulite lenses and in garnet porphyroblasts, (2) a N-S trending sub-vertical fabric (S2) preserved in low-strain domains and (3) upright folds (F3) associated with a ubiquitous steep E-W striking axial planar foliation (S3). Garnet in the granulites preserves relics of a prograde mineral assemblage M1a equilibrated at ~11.5 kbar and ~770–780°C, whereas the matrix granulite assemblage (M1b) from the S1 fabric attained peak pressure at ~13.5 kbar and ~850°C. The granulites were overprinted at ~8–11 kbar and ~850–900°C during crustal melting (M2) followed by partial re-equilibration (M3) at ~8 kbar and ~625°C. A garnet Lu–Hf age of 421.6 ± 1.2 Ma dates metamorphism M1, while a garnet Sm–Nd age of 385.3 ± 4.0 Ma reflects M3 cooling of the granulites. The mineral assemblage, M1, of the host migmatitic metapelite formed at ~9–12.5 kbar and ~760–810°C, partial melting and migmatization (M2) occurred at ~7 kbar and ~760°C and re-equilibration (M3) at ~5–6 kbar and ~675°C. A garnet Lu–Hf age of 409.7 ± 2.3 Ma dates thermal climax (M2) and a garnet Sm–Nd age of 356 ± 11 Ma constrains M3 for the migmatitic metapelites. The timing of this late phase is also bracketed by an emplacement age of syntectonic granite dated at c. 360 Ma. Decoupling of M1 and M2 P–T evolutions between the mafic granulites and migmatitic metapelites indicates their different positions in the crustal column, while the shared pressure–temperature (P–T) evolution M3 suggests formation of a mélange-like association during the late stages of orogeny. The high-pressure event D1-M1 is interpreted as a result of Late Silurian–Early Devonian moderate crustal thickening of a thermally softened and thinned pre-orogenic crust. The high-temperature (HT) re-equilibration D2-M2 is interpreted as a result of Mid-Devonian shortening of the previously thickened crust, possibly due to ‘Andean-type’ underthrusting. The D3-M3 event reflects Late Devonian supra-subduction shortening and continuous erosion of the sub-crustal lithosphere. This tectono-metamorphic sequence of events is explained by polyphased Andean-type deformation of a ‘Cascadia-type’ active margin, which corresponds to a supra-subduction tectonic switching paradigm.  相似文献   

义敦岛弧带弧后区板内岩浆作用的时代及意义   总被引：14，自引：0，他引：14  

曲晓明侯增谦  唐绍华 《岩石矿物学杂志》2003,22(2):131-137

通过对义敦岛弧夏囊沟一带酸性火山岩的岩石地球化学和Rb-Sr同位素研究,首次在该岛弧弧后区确立了一条板内火山岩带.这些火山岩属钾玄岩系列,以高K2O,低CaO,富Nb、Ta、Zr、Hf,贫Sr、Eu为特点,具标准的"V"型稀土元素配分型式,构造环境判别图解显示其形成于板内裂陷环境.由4个全岩样品给出的Rb-Sr等时线年龄t=189.2±5.0 Ma,相关系数R=0.999?824,ISr=0.714?578.认为火山岩的成分分异受斜长石在岩浆源区熔融残留和岩浆形成后黑云母的结晶分离双重控制.位于该带东侧弧后扩张盆地中的晚三叠世勉戈组双峰火山岩的形成年龄为213.1 Ma,说明该岛弧仅仅在24 Ma左右时限内就完成了从俯冲造弧到板内裂陷的重大转换,由此可对该岛弧带的碰撞造山过程和演化时序做出精确约束.  相似文献   

西南三江地区新生代走滑造山          下载免费PDF全文

尹福光  唐渊  徐波 《沉积与特提斯地质》2021,41(1):1-14

本文系统论述了西南三江地区那邦、高黎贡山、崇山-澜沧江、点苍山-哀牢山-红河剪切走滑带、区域性伸展与变质核杂岩、新生代盆地及走滑过程中的碱性岩浆活动等特征,认为西南三江地区经历了挤压收缩变形(60～40Ma)、走滑伸展热隆(40～38Ma)、走滑剪切深熔(38～23Ma)、走滑剪切伸展(23～11Ma)、走滑剥蚀隆升(...  相似文献