Pressure-Temperature Contours and PT Paths of the Early Precambrian Rocks through the Yinshan Area and Their Implication to the Crustal Evolution     

MEI Hualin  WU Changhua Tianjin Institute of Geology  Mineral Resources  CAGS  Tianjin.  JIN Wei Changchun University of Earth Sciences  Changchun  Jilin Hao Zhiguo Liu Xinzhu 《《地质学报》英文版》1998,72(1):14-28

Four distinct lithe-tectonic belts (zones) in the Yinshan area, North China, were identified by pressure-temperature contours and litho-tectonic features, such as the Sanggan granulite belt, Jining metasedimentary belt. Wulashan-Daqingshan front tectonic zone and Se' eratengshan belt. This area witnessed two important thermo-tectonic events. The older one is c. 2.5 Ga while the younger one c. 1.9 Ga. The Se' ertengshan Neoarchaean terrane features a clockwise PT path with the decompression ranging from > 1500 MPa to 800-1000 MPa in the Se' ertengshan belt, which implies an island arc setting. The Sanggan belt is a Mesoarchaean microcontinent reworked by Neoarchaean magma underplating, which shows an counterclockwise PT path. During the Palaeoproterozoic period, two Archaean continent (arc) collided. The Archaean basement of the Sanggan and Wulashan-Daqingshan belts overthrust northwards, the PTt paths of basement show a decompression from 1000-1200 MPa to 500-700 MPa. The PT paths of the Jining and Erda  相似文献   

Geochemistry of Eclogites and Metapelites from Trescolmen,Central Alps,as Observed from Major and Trace Elements and Oxygen Isotopes     

《International Geology Review》2012,54(2):95-119

Eclogites are often the only tangible high-pressure evidence we have from a paleosubduction zone, and they potentially preserve important geochemical information from the descending slab. Selected Group B/C eclogites and metapelites from the Trescolmen locality in the Adula nappe in the central Swiss Alps were chosen for a detailed investigation to determine oxygen isotope ratios and major- and trace-element compositions of the main rock-forming minerals. Complex major-element zonation patterns in garnet porphyroblasts indicate a pre-Alpine, medium-pressure growth history coupled with a high-pressure modification during the Alpine orogeny. Garnet REE patterns are notably HREE depleted in rim regions, with high overall REE content, particularly in the cores of grains. Omphacites are relatively homogenous in major elements, and show LREE- and HREE-depleted patterns, but with overall abundances of REEs lower than in garnets. These patterns are best explained by partitioning of the HREEs into garnet and the LREEs into zoisite. Oxygen-isotope systematics indicate limited fluid flow in eclogites and surrounding metapelites. δ¹⁸O values of quartz and garnet at the interface between eclogites and metapelites are indistinguishable and point to fluid exchange. Oxygen equilibrium conditions among rock-forming minerals, particularly between quartz and garnet in eclogites and metapelites, were reached, and fractionation indicates temperatures of ～600°C. The δ¹⁸O of unaltered eclogites (5.5 to 7.5 ‰) suggests a basaltic, MORB-type protolith.  相似文献   

气候变化对阴山北麓木本植物物候期的影响     

杨丽萍  张存厚  代海燕  吕迪波  韩君 《气象与环境学报》2020,36(1):102-107

本文基于内蒙古农牧业气象观测站1994—2015年旱柳、榆树和小叶杨三种木本植物物候观测资料及同期气候数据,采用线性倾向估计、Pearson相关系数等方法,探讨了气候变化对阴山北麓木本植物物候的影响。结果表明：近22 a,阴山北麓旱柳、榆树和小叶杨的花芽开放期和落叶末期均表现为提前趋势,且落叶末期提前幅度较大,平均每10 a分别提前2.9 d、3.6 d、4.6 d。生长季缩短,平均生长季长度为182 d。气温是影响旱柳、榆树、小叶杨春季花芽开放期的关键气象因子,春季气温每升高1℃,花芽开放期提前4.1 d;而落叶末期对降水量较为敏感,水分条件是阴山北麓木本植物落叶末期的主要限制因子。  相似文献   

江西银山铅锌矿床闪锌矿与石英流体包裹体的对比研究     

王国光  倪培  赵葵东  刘家润  解国爱  徐积辉  张志辉 《岩石学报》2011,27(5):1387-1396

赣东北地区是我国重要的铜铅锌金银多金属矿集区,银山铅锌(银)铜(金)多金属矿床是赣东北地区一个重要的大型次火山热液型多金属矿床。银山铅锌矿发育有闪锌矿-方铅矿-石英脉,前人研究认为金属矿物与脉石矿物为伴生关系,但是没有强调它们的成因上的联系。本次研究开展了矿石矿物中闪锌矿和伴生脉石矿物中石英的流体包裹体对比研究。通过详细的岩相学观察、显微测温、显微激光拉曼探针工作,对伴生石英脉和闪锌矿内原生包裹体,伴生石英脉中的晚期微细石英脉和闪锌矿内部次生包裹体进行流体特征的对比研究。研究结果显示,伴生石英脉原生流体包裹体比闪锌矿的原生包裹体的平均均一温度高约30℃,明显富集CH₄、N₂、CH₄、CO₂等挥发份,伴生石英脉中的晚期微细石英脉流体包裹体比闪锌矿次生包裹体的平均均一温度高23℃。闪锌矿原生包裹体与想伴生的早期石英脉在平均均一温度有所差别,气相成分差异明显,均表明矿石矿物与伴生脉石矿物可能形成于不同的地质环境,具有不同的温度和流体成分。  相似文献   

江西德兴孔家—银山火山盆地的时代归属：锆石U-Pb年代学证据   总被引：2，自引：0，他引：2       下载免费PDF全文

杨昔林  曹殿华李以科黄玉凤阚迎松刘盛祥 《中国地质》2011,38(1):86-93

江西银山铅锌多金属矿床是一个特大型火山-次火山热液矿床,容矿的孔家—银山火山盆地中火山-次火山岩通常被认为属于鹅湖岭组,但时代归属仍存在争议。本文对与银山火山岩伴生的英安斑岩进行了锆石LA-ICP-MS U-Pb年龄测定,获得了206Pb/238U年龄加权平均值为(181.3±2.1)Ma(MSWD=2.3,n=20),说明银山火山盆地形成于180 Ma左右,为早侏罗世的产物。对以往地质调查资料进行了分析,认为区域上鹅湖岭组为晚侏罗世有确切的地质证据,而早侏罗世孔家—银山火山盆地中火山-次火山岩不属于鹅湖岭组,该认识对研究区域地质演化及成矿规律有重要的意义。  相似文献   

阴山造山带和鄂尔多斯盆地北部磁异常场与结晶基底特征研究   总被引：4，自引：1，他引：3       下载免费PDF全文

阮小敏  滕吉文  安玉林  闫雅芬  王谦身 《地球物理学报》2011,54(9):2272-2282

阴山造山带与鄂尔多斯盆地跨越不同的构造单元,是典型的盆、山耦合地带,且是构造活动强、弱的变异地域,了解该区结晶基底分布特征对于深化认识盆山耦合的深部要素和深层动力学过程具有十分重要的意义.本文在最新的高精度的地磁观测剖面和数据采集基础上,与航磁异常场在该区域上的展布进行集成研究.通过磁场特征分析以研究盆地和造山带地域的...  相似文献   

The Jurassic structural evolution of the western Daqingshan area,eastern Yinshan belt,North China   总被引：1，自引：0，他引：1  

Yongchao Wang  Wei Shi  Xuanhua Chen  Limin Jia 《International Geology Review》2017,59(15):1885-1907

The western Daqingshan area, located in the eastern Yinshan belt, is dominated by the southern Daqingshan fold-and-thrust system and the northern Shiguai basin. Based on detailed structural investigations, stratigraphic controls, and geochronology, a three-stage tectonic evolution is proposed for the western Daqingshan area during the Jurassic. The discovery of syndepositional normal faults in the Early–Middle Jurassic sequences suggests that an N–S extensional regime (ca. 200–170 Ma) characterized the first deformational stage, which controlled the initial formation of the Shiguai basin. Subsequently, the relatively expansive rift basin was dissected by the initial development of the Daqingshan fold-and-thrust system that was associated with a N–S compressional regime (ca. 170–160 Ma). This phase of deformation involved the Lower–Middle Jurassic synrift sediments into a series of E–W-trending compressional structures, and controlled the deposition of Late–Middle Jurassic Changhangou growth strata ahead of the deformation front. Finally, the progression of Daqingshan fold-and-thrust system was dominated by NW–SE compression (ca. 160–145 Ma), which converted the previous E–W-trending compressional structures into a stepped geometry marked by several NE-trending oblique footwall ramps, and resulted in the depocentre of the Late Jurassic Daqingshan synorogenic conglomerate migrating markedly northeastwards. The driving mechanisms for these three palaeostress fields are considered as asthenosphere upwelling following Permian–Triassic collisional orogenesis, closure of the Mongol–Okhotsk Ocean, and NW-directed subduction of the Palaeo-Pacific plate, respectively.  相似文献   

阴山大青山山系特异重力场与深部构造   总被引：8，自引：2，他引：6  

王光杰  王谦身  滕吉文  齐伟威 《地球物理学进展》2004,19(3):602-607

根据阴山山系及邻近地区的布格重力异常分布特征,提出阴山山系和呼包盆地地区的布格重力异常分布与地形高程呈“同步型”的特异变化特征．通过重力数据资料的处理分析给出阴山山系和呼包盆地地区的地壳底界面都没有明显的下凹与上凸的特征,是阴山山系和呼包盆地布格重力异常呈现特异变化的可能原因。  相似文献   

赣东北银山多金属矿田成矿地质特征及矿床成因研究          下载免费PDF全文

匡文龙  王飞  余先川  李泽鹏  王桂安  张茜 《地质科学》2019,(1):244-264

赣东北地区成矿地质条件优越,形成有德兴、银山、乐华等大型矿田;其中,银山多金属矿田可分为两个成矿系列6个矿床。本文在实地考察和室内研究的基础上,从地层、岩性、构造、岩浆活动、矿体地质特征等分析入手,结合同位素测试、包裹体分析等手段,对银山多金属矿田的成矿地质特征及矿床成因进行了探讨,认为区内成矿物质主要来源于岩浆分异及热液作用,古老地层提供了部分成矿物质;成矿作用具有多期、多次、多成因特征,是典型的多位一体矿田。  相似文献   

内蒙古红山子地区新太古代变质侵入岩年代学及地球化学特征     

王春光  董晓杰  徐仲元  任云伟  王文龙  陈煜嵩 《吉林大学学报(地球科学版)》2019,49(3):709-726

华北克拉通西部陆块阴山地块花岗-绿岩带中出露的花岗岩类型比较复杂,研究其类型、成因及其与绿岩带之间的联系,对于探讨花岗-绿岩带的形成和演化有重要意义。本文对内蒙古三合明铁矿西侧红山子地区的花岗-绿岩带进行了研究。其不仅包含有大量的变质科马提岩、科马提质玄武岩和拉斑玄武岩等绿岩带的表壳岩,而且发育着多种变质侵入岩。研究表明,区内与绿岩带相关的侵入岩主要有3种,即变质英云闪长岩、变质花岗闪长岩、变质花岗岩,本文对其中的变质英云闪长岩和变质花岗岩两种岩石进行了地球化学和锆石测年的研究。变质英云闪长岩是一套富铝、低钾、贫铁镁和稀土元素强烈分异的太古宙高铝型TTG岩,SHRIMP锆石U-Pb测年为(2 534±7)Ma(MSWD=1.3),与研究区南部的赞岐岩和TTG的年龄相同;而变质花岗岩具有高硅、富碱,低铁、镁、钛、锰的特点,是一套钙碱性的过铝质岩石,SHRIMP锆石U-Pb测年为(2 509±7)Ma(MSWD=1.5),野外地质现象表明变质花岗岩明显地侵入到区内的绿岩地层和变质英云闪长岩之中。研究发现变质英云闪长岩形成于板块俯冲时TTG岩系岩浆弧构造环境,而变质花岗岩成因则可能与加厚地壳中变沉积岩的熔融有关。  相似文献