豫西伊川地区中元古界兵马沟组泥质岩地球化学特征及其环境与物源示踪   总被引：1，自引：0，他引：1       下载免费PDF全文

郑德顺  孙风波  程涌  张飞鹏 《高校地质学报》2016,22(2):254

华北克拉通南缘古-中元古代构造-沉积演化的俯冲说、裂解说之争由来已久,兵马沟组作为熊耳群形成后的第一套碎 屑沉积岩层,对解释上述过程有重要意义。该文通过对豫西伊川地区的兵马沟组泥质岩微量及稀土元素的地球化学特征分析, 探讨了其沉积环境、物源,进而揭示了其发育的大地构造背景。结果表明：（1）兵马沟组泥质岩稀土元素含量高,球粒陨石标准 化后轻重稀土分异明显,δEu负异常,δCe异常不明显,富集Rb、Th、La、Ce、Nd、Zr、Hf 等,较上地壳平均值富集Sc、V、Cr、Co、Ni、 Rb;（2）Ceanom指数、V/V + Ni反映了泥质岩沉积时的还原环境,Sr/Ba、B/Ga表明其为由陆相至海相的过渡型沉积;（3）Cr/Zr、Th/U 等元素比值关系反应其物源无深部物质加入,La/Yb-Ce、Co/Th-La/Sc图解表明物源为中酸性火山岩及少量稳定陆壳物质; （4）Th-Sc-Zr/10、Th-Co-Zr/10图解表明其物源主要来自大陆岛弧。综合上述分析结果,结合区域地质信息,可以得出中元古界 兵马沟组形成于大陆岛弧弧后盆地,熊耳群分布区为中元古代俯冲成因的大陆岛弧区。  相似文献   

New paleomagnetic data on the Anabar Uplift and the Uchur-Maya region and their implications for the paleogeography and geological correlation of the Riphean of the Siberian Platform     

R. V. Veselovskiy  V. E. Pavlov  P. Yu. Petrov 《Izvestiya Physics of the Solid Earth》2009,45(7):545-566

The results of paleomagnetic studies of the reference sections of the Riphean and Late Proterozoic intrusive bodies of two remote areas of the Siberian Platform are presented. Within the limits of the Uchur-Maya region the sedimentary rocks of the Gonam, Omakhta, Ennin and Konder formations were studied; and the Riphean sedimentary rocks of the Burdur and Kotuykan formations on the northern and western slopes of the Anabar Uplift and, also, the Late Proterozoic intrusive complexes, located in the basins of the Fomich, Magan, Dzhogdzho and Kotuykan Rivers were studied. The paleomagnetic poles obtained in the course of this work and the present-day geochronological data give grounds to assume that: (1) the accumulation of the Riphean of the Anabar Uplift occurred after the formation of the Uchurskaya series of the Uchur-Maya region and was completed in approximately 1.5 Ga; (2) the Konder layers, compared according to the correlation pattern accepted at the present time [Semikhatov and Serebryakov, 1983] with the bottoms of the Totta formation, can be related to the appreciably more ancient stratigraphic level; (3) the intrusion of the studied intrusive bodies of the northern and western slopes of the Anabar Uplift occurred nonsimultaneously, although within close time intervals of approximately 1.5 Ga. The estimates of the kinematic parameters of the drift of the Siberian Platform within an interval of 1.7–1.0 Ga is carried out.  相似文献   

Stenian A-type granitoids in the Namaqua-Natal Belt,southern Africa,Maud Belt,Antarctica and Nampula Terrane,Mozambique:Rodinia and Gondwana amalgamation implications     

《地学前缘(英文版)》2019,10(6):2265-2280

We carried out SHRIMP zircon U-Pb dating on A-type granitic intrusions from the Namaqua-Natal Province,South Africa,Sverdrupfjella,western Dronning Maud Land,Antarctica and the Nampula Province of northern Mozambique.Zircon grains in these granitic rocks are typically elongated and oscillatory zoned,suggesting magmatic origins.Zircons from the granitoid intrusions analyzed in this study suggest~1025-1100 Ma ages,which confirm widespread Mesoproterozoic A-type granitic magmatism in the Namaqua-Natal(South Africa),Maud(Antarctica) and Mozambique metamorphic terrains.No older inherited(e.g.,~2500 Ma Achean basement or~1200 Ma island are magmatism in northern Natal)zircon grains were seen.Four plutons from the Natal Belt(Mvoti Pluton,Glendale Pluton,Kwalembe Pluton,Ntimbankulu Pluton) display 1050-1040 Ma ages,whereas the Nthlimbitwa Pluton in northern Natal indicates older 1090-1080 Ma ages.A sample from Sverdrupfjella,Antarctica has~1091 Ma old zircons along with~530 Ma metamorphic rims.Similarly,four samples analysed from the Nampula Province of Mozambique suggest crystallization ages of~1060-1090 Ma but also show significant discordance with two samples showing younger~550 Ma overgrowths.None of the Natal samples show any younger overgrowths.A single sample from southwestern Namaqualand yielded an age of~1033 Ma.Currently available chronological data suggest magmatism took place in the Namaqua-Natal-MaudMozambique(NNMM) belt between~1025 Ma and~1100 Ma with two broad phases between~1060-1020 Ma and 1100-1070 Ma respectively,with peaks at between~1030-1040 Ma and~1070-1090 Ma.The age data from the granitic intrusions from Namaqualand.combined with those from Natal,Antarctica and Mozambique suggest a crude spatial-age relationship with the older1070 Ma ages being largely restricted close to the eastern and western margins of the Kalahari Craton in northern Natal,Mozambique.Namaqualand and WDML Antarctica whereas the younger 1060 Ma ages dominate in southern Natal and western Namaqualand and are largely restricted to the southern and possibly the western margins of the Kalahari Craton.The older ages of magmatism partially overlap with or are marginally younger than the intracratonic Mkondo Large lgneous Provinee intruded into or extruded onto the Kalahari Craton,suggesting a tectonic relationship with the Maud Belt.Similar ages from granitic augen gneisses in Sri Lanka suggest a continuous belt stretching from Namaqualand to Sri Lanka in a reconstituted Gondwana,formed during the terminal stages of amalgamation of Rodinia and predating the East African Orogen.This contiguity contributes to defining the extent of Rodinia-age crustal blocks,subsequently fragmented by the dispersal of Rodinia and Gondwana.  相似文献   

Assembly and Breakup of Rodinia (Some results of IGCP project 440)   总被引：2，自引：0，他引：2  

S. V. Bogdanova  S. A. Pisarevsky  Z. X. Li 《Stratigraphy and Geological Correlation》2009,17(3):259-274

The principal results of project 440 “Assembly and Breakup of Rodinia” of the International Geological Correlation Programme (IGCP) are reviewed in this work. A map of that supercontinent compiled using geological and paleomagnetic data describes global paleogeography 900 Ma ago. The assembly of Rodinia, which comprised most of Precambrian continental blocks, lasted ca. 400 m.y. (from 1300 to 900 Ma). Its breakup presumably triggered by mantle superplume took place between 830 and 650 Ma. The correlation between tectonic events in different continental blocks is considered. Some problems concerning the Rodinia reconstruction and history, e.g., the slow growth of juvenile crust and effects of mantle-plume events during the amalgamation period and of glaciations at the breakup time, are discussed. The latter caused changes in the biosphere and climate, whereas postglacial periods stimulated progress in biota evolution.  相似文献   

云南东川地区昆阳群黑山组凝灰岩锆石SHRIMP U—Pb年龄及其地层学意义     

孙志明  ;尹福光  ;关俊雷  ;刘建辉  ;李军敏  ;耿全如  ;王立全 《中国区域地质》2009,(7):896-900

云南东川地区昆阳群的形成时代及地层层序一直令人关注,已获得的一些数据虽然具有参考意义,但高质量的SHRIMP定年还很缺乏。在东川地区昆阳群黑山组中上段发育的近180m厚的具有地层意义的晶屑、岩屑凝灰岩中采集样品D0202一件,选出锆石百余粒,获得SHRIMPU-Pb加权平均年龄为（1503±17）Ma。样品D0202的锆石Th／U大于0．48,并具清晰的振荡环带结构,均为岩浆成因的锆石,表明黑山组形成于中元古代早期。这一年龄表明昆阳群的形成时代至少大于1500Ma,为准确地标定昆阳群的时代和层序提供了新的参考依据。  相似文献   

Initial accretion of the North Qinling Terrane to the North China Craton before the Grenville orogeny: constraints from detrital zircons   总被引：2，自引：0，他引：2  

Xuefei Liu  Pengfei Zuo  Leon Bagas  Yuliang He  Deshun Zheng 《International Geology Review》2019,61(1):109-128

Whether the North Qinling Terrane (NQT) was accreted to the North China Craton (NCC) in the Proterozoic is still a matter of debate. We report the first detrital zircon study from the Baishugou Formation, which forms the uppermost part of the Mesoproterozoic Guandaokou Group, at the southernmost NCC margin. Detrital zircons from carbonaceous silty phyllite in the lower part of the Baishugou Formation yield U–Pb ages peaking at ca. 2500 Ma, with minor peaks at ca. 2300–2000, 1800, and 1600 Ma, and εHf(t) values ranging from ?10.8 to +9.1. These zircons are considered to have been sourced from the NCC. In contrast, the middle-to-upper part of the formation contains detrital zircons which yield an age group ranging from 1800 to 1000 Ma, with peaks at 1800, 1500, 1300, and 1100 Ma; the zircons with ages of 1500–1300 Ma dominantly have εHf(t) values greater than +5 and the majority plot along the depleted mantle evolution curve. The striking difference between the U–Pb ages of the detrital zircons from the upper and lower parts of the formation suggests a shift in provenance. Magmatism at 1500–1300 Ma has not been reported from the southern margin of the NCC but has been discovered in the NQT. Hence, we deduce that the zircons from the upper part of the formation were primarily derived from the NQT, where an episode of crustal growth and magmatism is recorded between 1500 and 1100 million years. The variable sediment provenances imply that the NCC and NQT could be connected during the late Mesoproterozoic to early Neoproterozoic. The pattern of detrital zircon ages in the new sediments from the Baishugou Formation is distinct from those in the Kuanping Group and the Palaeozoic Erlangping Complex, which are at present sandwiched between the NCC and the NQT. The detrital zircons from these two groups are dominated by an age peak at ca. 1000 Ma, which is formed as the result of amalgamation of the NQT and the Rodinia Supercontinent during the Grenville orogeny. It is possible that the new sediments of the Baishugou Formation were deposited before Grenville orogeny.  相似文献   

塔里木克拉通东北缘Columbia超大陆裂解事件：库鲁克塔格地区辉绿岩床的地球化学、锆石U-Pb年代学和Hf-O同位素证据     

张健  李怀坤  张传林  田辉  钟焱  叶现韬 《地学前缘》2018,25(6):106-123

研究塔里木克拉通东北缘库鲁克塔格地区发育的中元古代早期基性岩浆活动,对深入了解Columbia超大陆裂解过程具有重要意义。本文报道了库鲁克塔格地区侵入于兴地塔格群的阿斯廷布拉克辉绿岩床SHRIMP锆石U-Pb年龄,结合岩石学、地球化学和Nd-Hf-O同位素资料,对该基性岩的形成时代、岩浆起源和源区类型以及岩浆作用的动力学背景进行讨论。研究表明：辉绿岩锆石具有高Th/U比值(>1),CL图像带状分区,显示基性岩浆锆石特点,207Pb/206Pb 加权平均年龄(1 551±8) Ma代表辉绿岩的形成时代,锆石δ18O值为5.52‰~6.53‰(正态分布的峰值为5.8‰),略高于地幔锆石的变化范围。辉绿岩高FeOT(11.4%~13.4%),低MgO(5.46%~7.11%)和TiO2(1.51%~2.45%),具有拉斑质属性,轻、重稀土元素分馏明显((La/Yb)N=4.6~5.4),具弱的Eu正异常(δEu=1.05~1.27),富集大离子亲石元素(LILE),亏损Nb、Ta等高场强元素(HFSE),微量元素组成与大陆溢流玄武岩(CFB)类似,全岩Nd(εNd(t)=-3.8~-1.8)和锆石Hf(εHf(t)=-3.7~1.9)同位素均显示岩浆来自富集地幔。阿斯廷布拉克辉绿岩是被交代的大陆岩石圈地幔部分熔融的产物,形成于板内的拉张环境,与该时期全球构造演化体制相吻合,属于中元古代早期Columbia超大陆裂解事件。  相似文献   

中条山篦子沟铜矿辉钼矿铼-锇同位素年龄及其地质意义     

耿艳光  简伟  李洪英  叶会寿  毕珉烽  胡乔青  李超  范成龙  王梦琦 《吉林大学学报(地球科学版)》2017,(5):1405-1418

篦子沟铜矿位于山西中条山胡-篦型铜矿田,矿体与地层产状一致,呈层状、似层状分布于中条群篦子沟组和余元下组中,经历了多期次多阶段成矿作用。为限定篦子沟铜矿后期热液脉状矿化的形成时代,对篦子沟铜矿区方解石-石英脉中与黄铜矿共生的辉钼矿样品进行了Re-Os同位素测定。结果表明,6件辉钼矿样品Re-Os同位素模式年龄为(1 539±26)~(1 616±26)Ma,加权平均年龄为(1 577±31)Ma(MSWD=5.5),等时线年龄为(1 522±180)Ma(MSWD=9.6),表明热液脉状矿化形成于中元古代长城纪晚期。据此篦子沟铜矿的热液脉状矿化可分为3个成矿期次,分别为古元古代晚期发生的微细脉浸染状矿化期、脉状矿化期和中元古代早期热液脉状辉钼矿矿化期。此次事件可能为中元古代伸展-裂解事件岩浆侵位产生的热液对原来的篦子沟铜矿进行再次的矿化、富集。结合已有资料,证明篦子沟以及中条山地区在中元古代早期存在热液矿化事件。  相似文献   

山西黎城中元古界常州沟组微生物成因构造(MISS)及其地质意义     

郑伟  邢智峰 《现代地质》2015,29(4):825-832

在山西黎城县西井镇彭庄至大井盘公路旁剖面以及黄崖洞景区发育大量的微生物成因构造(MISS),多发育在砂岩表面。由于构造形态奇特,被误以为各种遗迹化石或是不规则的泥裂构造。依据其形态特征、成因构造和前人分类方案,将研究区此类构造分为3种类型,即微生物席生长构造、微生物席破坏构造和微生物席腐烂构造,以及9个不同形态构造,即小瘤状突起、圆顶大瘤状突起、不规则侧向生长脊、大脊状生长构造、纺锤状脱水裂痕、多边形网状脱水裂痕、曲形脱水裂痕、微生物席砂片、砂火山构造,对9种不同形态的MISS进行了详细的论述。对研究区微生物成因构造(MISS)的成因进行了探讨,与豫西鲁山地区、贺兰山苏峪口地区、北京南口地区、河北兴隆地区发育的MISS及地层特征进行类比,认为MISS对华北地台中元古代地层对比以及古环境研究有重要的指导意义。  相似文献   

浙江章村地区中元古代岛弧火山岩的地球化学及构造意义     

杨树锋  顾明光  卢成忠 《吉林大学学报(地球科学版)》2009,39(4)

浙江章村地区中元古代双溪坞群火山岩是江南造山带的重要组成部分,下部北坞组以中基性至中酸性凝灰岩类为主,中部岩山组以沉凝灰岩类占优势,上部章村组以中酸性至酸性熔结凝灰岩类为特色,形成较完整的中基性-酸性火山岩演化序列。岩石化学和稀土元素、微量元素地球化学均指示其形成于岛弧环境,反映为大陆边缘岛弧挤压背景下同源岩浆连续分异过程中火山作用的产物,自下而上显示了岛弧逐步增大并不断成熟的过程。从所见物质成分分析,它经历了北坞期火山岛弧陆相喷发-岩山期火山间歇弧内盆地沉积-章村期火山岛弧陆相爆溢3个阶段,在经历了持续的火山活动之后,区内之龙门山岛弧处于挤压体制之中并褶皱造山,其起因与Rodinia超大陆发生聚合造山作用有关。  相似文献