北苏鲁超高压变质带前寒武纪基底研究新进展   总被引：1，自引：0，他引：1  

徐扬  杨坤光  李日辉  侯方辉  秦亚超 《现代地质》2013,27(2):248-259

北苏鲁超高压变质带位于胶东牟平-即墨断裂以东的地区,其前寒武纪基底以出露新元古代的双峰式火成岩为主要特征,其主要岩石组合包括大量花岗片麻岩以及少量变（超）基性岩（榴辉岩）、变沉积岩。对花岗片麻岩、变质（超）基性岩的岩石组合、地球化学、锆石U-Pb和Lu-Hf同位素的研究表明,北苏鲁存在新太古代-古元古代的残留地壳,经历了1.8~2.2 Ga期间的岩浆-火山-变质事件;新元古代中期（0.72~0.80 Ga）与Rodinia超大陆的裂解相关的岩浆活动促使地壳的生长和再造,形成了北苏鲁的前寒武纪基底的主体;北苏鲁和苏鲁-大别造山带一样,其前寒武纪基底是扬子板块北缘的一部分,苏鲁造山带的西北边界是五莲-烟台断裂带。  相似文献   

山东胶南威海造山带荣成岩套花岗质片麻岩的形成时代——锆石SHRIMP U-Pb定年   总被引：1，自引：0，他引：1       下载免费PDF全文

王世进  万渝生  宋志勇  王伟  董春艳  张贵丽 《山东国土资源》2012,28(5):1-8

胶南-威海造山带荣成岩套花岗质片麻岩由闪长质片麻岩-石英闪长质片麻岩-英云闪长质片麻-一奥长花岗质片麻岩-花岗闪长质片麻岩-黑云二长花岗质片麻岩-二长花岗质片麻岩类组成,早期为TTG质花岗岩,晚期为二长花岗岩类。自早到晚存在明显的富钾演化特征。根据新的SHRIMPU-Pb锆石定年结果,该岩套早期闪长质片麻岩年龄为（741±10）Ma,英云闪长质片麻岩年龄为780-760Ma。晚期二长花岗质片麻岩年龄为760-714Ma。所以,可把荣成岩套花岗岩时代限定在800-700Ma之间（南华纪）,其形成与华北克拉通岩石圈减薄有关。  相似文献   

松辽盆地西缘断裂带中花岗质糜棱岩的锆石SHRIMP和云母氩-氩年龄及其构造意义   总被引：1，自引：0，他引：1  

郑常青  李娟  金巍  周建波  施璐  崔芳华  韩晓萌 《吉林大学学报(地球科学版)》2015,45(2):349-363

松辽盆地西缘发育大型的北北东走向韧性断裂带,该韧性断裂带的性质、活动时限一直存在争议,制约了对松辽盆地构造成因的认识以及松辽盆地西缘油气勘探开发的进展。腾克、金星及嘎拉山地区是松辽盆地西缘韧性断裂带的代表性出露区,主体岩石组合为条带状花岗质糜棱岩、眼球状花岗质糜棱岩等。腾克、金星及嘎拉山地区发育一组糜棱面理和线理,其中面理为110°~135°∠45°~65°、线理为倾伏向10°~25°,倾伏角10°~35°;其运动性质均显示左行走滑特征。确定韧性断裂带活动时限的样品采自构造带内花岗质糜棱岩的锆石和同变形云母,其中锆石SHRIMP谐和年龄为296.9~299.4 Ma;黑云母⁴⁰Ar-³⁹Ar年龄为(123.0±0.7)Ma,白云母的⁴⁰Ar-³⁹Ar年龄为(124.4±0.9)Ma。松辽盆地西缘韧性断裂带应该属于嫩江断裂带的北段。年龄结果表明该韧性断裂带中花岗岩侵位于晚石炭世,大型北北东向韧性构造变形发生于早白垩世。腾克金星嘎拉山剪切带控制松辽盆地西缘,同时表明松辽盆地在早白垩世经历了走滑挤压盆地演化阶段,这种大型北北东向韧性断裂带的形成可能与当时西太平洋伊泽纳崎板块向欧亚大陆俯冲发生转向有关。  相似文献   

扬子西北缘碧口块体花岗质岩体锆石U-Pb年龄、Hf同位素特征及其地质意义     

平先权  郑建平  熊庆  张志海  夏冰 《吉林大学学报(地球科学版)》2014,44(4):1200

对扬子西北缘碧口块体中白雀寺和大安花岗质岩体进行了锆石U-Pb定年及Hf同位素研究。结果表明,白雀寺岩体的年龄分2组:(855±6) Ma（n=23）和(917±14) Ma（n=3）。前者ε_Hf(t)为3.8~10.4,一阶段Hf模式年龄为1.00~1.27 Ga;后者ε_Hf(t)为2.0~8.1,一阶段Hf模式年龄为1.14~1.40 Ga。而大安岩体给出了6组不同的年龄：(854±10) Ma（n=3）、(801±7) Ma（n=3）、(702±10) Ma（n=3）、(565±6) Ma（n=1）、(246±7) Ma（n=1）和(207±2) Ma（n=1）。其ε_Hf(t)为-12.6~11.4（t=854 Ma）,一阶段和二阶段Hf模式年龄分别为0.95~1.90 Ga和1.02~2.55 Ga。白雀寺和大安岩体的侵位年龄分别为(855±6) Ma和(854±10) Ma,代表了扬子西北缘碧口块体内的一次重要岩浆事件,前者主体来源于中元古代新生陆壳源区,而后者主要来源于中元古代新生陆壳与晚太古代地壳物质的混合源区。此外,白雀寺岩体中(917±14) Ma的年龄代表新元古代早期的岩浆活动,而大安岩体中年轻的年龄可能记录着岩体后期所经历的复杂热改造事件。  相似文献   

Geochemistry and petrogenesis of the Cretaceous A‐type granites in the Laoshan granitic complex,eastern China     

Quanshu Yan  Xuefa Shi 《Island Arc》2014,23(3):221-235

Major element and trace element compositions, and Sr, Nd and Pb isotopic compositions for postcollisional granites from the Laoshan granitic complex, in the eastern side of the Triassic suture between the South China and North China tectonic blocks were determined. The granites are alkaline, A‐type and can be further classified as A1 granites. The trace element composition of these granites is transitional between those of oceanic island basalt and enriched mid‐oceanic ridge basalt, with depletions in Ba, Sr, P, and Ti that can be ascribed to mineral fractionation and enrichments in Cs, Rb, Th and U possibly resulted from the involvement of slab fluids. The isotopic signature of Laoshan granites represent a mixture between an enriched mantle type 1 (EMI)‐like end‐member and lower continental crust (LCC). We propose that the magmas that formed the Laoshan A1 granites are a mixture between those derived from the EMI‐like delaminated eclogitic rocks (subsequently enriched by fluids released from Mesozoic Pacific subducted slab) and those derived from the LCC, which consists of granulites or metamorphic residues from the prior generation of I‐type granites in the region. The mixed magmas then experienced a strongly alkali feldspar‐dominated fractionation prior to their emplacements as A‐type granites in the Laoshan granitic complex.  相似文献   

Characterization of the Mefjell plutonic complex from the Sør Rondane Mountains, East Antarctica: Implications for the petrogenesis of Pan-African plutonic rocks of East Gondwanaland     

Zilong  Li  Yoshiaki  Tainosho  Jun-Ichi  Kimura  Kazuyuki  Shiraishi 《Island Arc》2005,14(4):636-652

Abstract The Mefjell plutonic complex consists of 500–550‐Ma Pan‐African plutonic rocks, which intrude into the Precambrian crystalline basement in the Sør Rondane Mountains, East Antarctica, and forms part of the Sør Rondane Suture Zone. The complex comprises syenitic and granitic (mostly monzogranitic) rocks, and is characterized by the presence of iron‐rich hydrous mafic minerals and primary ilmenite, both of which imply its formation at high temperature and under low oxygen fugacity conditions. The syenitic rocks are metaluminous, and are high in alkalis, K₂O/Na₂O, Al₂O₃, FeO_t/(FeO_t + MgO) (0.88–0.98), K/Rb (800–1000), Ga (18–28 p.p.m.), Zr (up to 2100 p.p.m.) and Ba. They also have a low Mg? (Mg/[Mg + Fe²⁺]), Rb, Sr, Nb, Y and F, low to moderate light rare earth element (LREE)/heavy rare earth element (HREE) ratios and positive Eu anomalies in their rare earth element (REE) patterns. The granitic rocks are metaluminous to peraluminous, and have a high Rb content, high Sr/Ba and LREE/HREE ratios, low K/Rb and negative Eu anomalies. Most of the syenitic and granitic rocks have Y/Nb ratios greater than 1.2, and are depleted in Nb, Ti and Sr on the primitive mantle‐normalized spider diagrams, indicating a crustal origin with subduction zone signatures. We interpret both the syenitic and granitic rocks to be derived from an iron‐rich lower crustal source by dehydration melting induced by the heat of mantle‐derived basaltic intrusion, after which they then underwent limited fractional crystallization. The Mefjell plutonic complex has a high Zr content and tectonic discrimination diagram signatures indicative of normal A‐type granitic rocks. Both rock suites may have been generated under the same postorogenic tectonic setting. The Mefjell syenitic rocks are chemically comparable to charnockites in the Gjelsvikjella and western Mühlig‐Hofmannfjella areas of East Antarctica, whereas the granitic rocks are comparable to aluminous A‐type granitic rocks in South India, which were emplaced during formation and evolution of the Gondwanaland supercontinent.  相似文献   

苏鲁超高压变质带西北缘五莲断裂外侧浅变质花岗片麻岩的地球化学特征与原岩成因研究   总被引：6，自引：0，他引：6       下载免费PDF全文

薛怀民  刘福来  许志琴 《中国地质》2005,32(2):249-258

五莲杂岩中的正片麻岩主要为正长花岗质片麻岩，少数石英正长质片麻岩，具有适度碱性的演化趋势。以贫CaO、低MgO、高Na2O为特征，岩石中虽然碱度较高，但仍属较强过铝型。这套正片麻岩还表现为较强的轻、重稀土元素分馏程度和强的负Eu异常，尤以强烈富集大离子亲石元素（Rb、Ba、Th、U、K)和亏损高场强元素Ti、Zr、Hf．Nb、Ta(部分样品中Zr、Hf除外)，明显的Ba、P负异常为显著特征。岩石地球化学的总体特征与苏鲁造山带内的花岗质片麻岩有一定的可比性，而与华北克拉通内的前寒武纪正片麻岩明显不同。推测五莲地区正片麻岩的原岩是晚元古代由大陆下地壳富钾的变质玄武质组分部分熔融形成的，母岩浆的演化主要表现为以长石(奥长石和钾长石)的分离结晶为主，其中可能还有少量黑云母和角闪石，以及副矿物锆石和磷灰石的分离结晶。  相似文献   

STUDY ON TECTONIC FEATURE AND METALLOGENIC MECHANISM OF THE PENGSHAN Sn-Pb-Zn POLYMETALLIC OREFIELD, JIANGXI PROVINCE     

LU Shudong*  DU Yangsong  XIAO E  XU Chunwei 《大地构造与成矿学(英文版)》2005,29(1):71-83

The Pengshan area is located in the Jiujiang-Ruichang region, which is a segment of the middle-lower Yangtze River metallogenic belt, located on the side of the Yangtze plate on the north boundary in the joint area of the Yangtze Plate and South China Plate - “Jiangnan Collision-Shearing Belt”. Also many researches have been well done on the magma system and the mineralization system in the areas by Wu Liangshi, Lu Xinbiao and Cui Bin (Wu, 1998; Wu and Wu, 1999; Lu et al., 1997; Cu…  相似文献   

大兴安岭阿龙山地区花岗片麻岩的同位素年龄与超大陆   总被引：1，自引：0，他引：1  

赵海滨韩振哲  刘旭光 《华东地质学院学报》2005,28(4):313-316

阿龙山花岗质片麻岩是在阿龙山镇幅1：25万区调过程中从兴华渡口岩群变质杂体中解体出的古花岗质侵入体。阿龙山地区的花岗片麻岩的锆石U-Pb年龄的测定结果表明，其原岩形成时代为1100Ma左右，在565Ma曾受到高温变质作用。两组年龄的获得为大兴安岭地区早期大陆裂解及碰撞造山作用的确定提供了直接证据，这一结果表明额尔古纳微陆块曾经历了格林威尔期和罗丁尼亚超大陆的聚合、裂解和冈瓦纳泛大陆的再造的多次开合作用。  相似文献   

The spatial distribution of trace elements in topsoil from the northern slope of Qomolangma (Everest) in China     

Y. L. Zhang  Z. F. Wang  K. L. Luo  M. J. Ding  W. Zhang  X. D. Lin  X. C. Yang 《Environmental Geology》2007,52(4):679-684

The environment of Mt. Qomolangma (Everest) area is of great significance to the global environmental background and environmental change research. However, there are few studies on the content and distribution of soil trace elements in the area. About 130 soil samples were collected nearby the Rongbuk valley at the northern slope of the Qomolangma from 4,400 to 6,600 m elevations. Nine soil trace elements, Cr, Zn, Sr, Pb, Ni, Co, Cd, Mn, Cu, were analyzed with ICP-AES (inductively coupled plasma atom emission spectrometry). The results showed that soil trace elements content increased with altitude; the content of the Cd in this area was very high, which was 5.8 times of the average content of Chinese soil. There was a noticeable change point for soil trace elements content at the altitude of 5,800 m, and the content of Cd increased abruptly above 5,800 m. This point was just located at the boundary of two types of rocks. The Late Precambrian-Neoproterozoic granite–gneiss and metacryst migmatized interbedded with marble located below 5,800 m; black-dark slate and marl of Cambrian located above 5,800 m (including 5,800 m), the geochemical characteristic of different rocks was the main factors controlling the soil trace elements content in the northern slope of Qomolangma Mountain.  相似文献