| 皖南地区城安花岗闪长岩锆石U-Pb年龄及其形成的温压条件 |
| |
| 引用本文： | 汪雅菲,杜建国,陈秀其,徐锦龙,刘道彬,葛海影.皖南地区城安花岗闪长岩锆石U-Pb年龄及其形成的温压条件[J].地质科学,2019,54(2):529-548. |
| |
| 作者姓名： | 汪雅菲 杜建国 陈秀其 徐锦龙 刘道彬 葛海影 |
| |
| 作者单位： | 安徽省地质调查院 合肥230001;安徽省地质调查院 合肥230001;安徽省地质调查院 合肥230001;安徽省地质调查院 合肥230001;安徽省地质调查院 合肥230001;安徽省地质调查院 合肥230001 |
| |
| 基金项目： | 中国地质调查局国土资源大调查项目“安徽1∶50 000横船渡;乌石垄;城安;郭村幅 |
| |
| 摘 要： | 安徽省南部地区城安岩体位于扬子板块东段江南隆起带内，是燕山期大规模岩浆作用的代表性岩体之一。1∶50 000“城安幅”区域地质调查成果发现该岩体为一花岗闪长岩—二长花岗岩—正长花岗岩组成的复式岩体，构成了皖南地区岩石类型复杂的独立复式岩体，它是探讨该地区中生代花岗岩形成过程的“窗口”，前人对该岩体的研究程度较低。本文通过对其研究，可为深入探讨皖南地区中生代花岗岩的岩浆物质来源提供年代学以及矿物学方面制约和实物佐证。运用锆石U-Pb年代学（LA-ICP-MS）和电子探针（EPMA）方法，精确测定城安岩体主体岩性（花岗闪长岩中核部年龄和成岩年龄）。通过对岩石中钾长石、斜长石、黑云母等矿物含量的分析，讨论岩浆形成的温压条件和岩石成因。结果表明：城安岩体中花岗闪长岩核部年龄可分为两组，818～740 Ma和222～204 Ma，分属新元古代拉伸纪—成冰纪和中生代晚三叠世，前者对应前寒武纪罗迪尼亚大陆裂解事件，后者推测可能与大别造山带折返过程相关。岩体成岩年龄为151.0±2.8 Ma （MSWD = 0.91），表明岩浆结晶冷却年龄在晚侏罗世。城安岩体为Ⅰ型花岗岩，形成的温度在680±55 ℃，压力范围在0.21～0.30 GPa，深度在6.93～9.90 km。该岩体形成机制主要为地壳物质部分融熔。
|
| 关 键 词： | 花岗闪长岩 LA-ICP-MS锆石U-Pb测年 P-T条件 皖南城安 |
| 收稿时间： | 2018-05-10 |
Zircon U-Pb geochronology and temperature-pressure conditions study of Cheng’an intrusion in southern Anhui area |
| |
| Wang Yafei Du Jianguo Chen Xiuqi Xu Jinlong Liu Daobin Ge haiying.Zircon U-Pb geochronology and temperature-pressure conditions study of Cheng’an intrusion in southern Anhui area[J].Chinese Journal of Geology,2019,54(2):529-548. |
| |
| Authors: | Wang Yafei Du Jianguo Chen Xiuqi Xu Jinlong Liu Daobin Ge haiying |
| |
| Institution: | Anhui Institute of Geological Survey, Hefei 230001 |
| |
| Abstract: | The Cheng’an intrusion in southern Anhui Province is located at the Jiangnan uplift belt, eastern Yangtze plate, is one of the most important intrusive bodies of Yanshanian magmatism. The result of 1∶50 000 regional geological surveying of the Cheng’an sheet shows that the Cheng’an rock mass is a composite one consisted of granodiorite, adamellite and orthoclase granites. It constitutes an independent complex rock mass with complex rock types in southern Anhui, it is a “window” to explore the formation process of Mesozoic granites in this area, and the predecessors research degree of the rock mass is lower. This paper can provide chronological and mineralogical constraints and physical evidence for further discussion on magmatic material sources of Mesozoic granites in southern Anhui. Use the method of zircon U-Pb chronology （LA-ICP-MS） and scanned microscope （SEM）, precise measured the zircon core age and diagenetic age of granodiorite which is the major lithology of the intrusion. Discuss the temperature-pressure conditions of magma formation and petrogenesis by analyzing the contents of potash feldspar, plagioclase and biotite in rock. The results showed that the zircon core age of the granodiorite can be individed into two groups：818～740 Ma and 222～204 Ma, which belongs to Tonian-Cryogenian of new Proterozoic and Mesozoic Late Triassic, the former corresponds the breakup of the Rodinia supercontinent in Precambrian, and the latter is expected to be related to the exhumation of the Dabie Mountains. The diagenetic age of the intrusion was dated to be 151.0±2.8 Ma （MSWD = 0.91）, which shows the magma crystallization and cooling in Late Jurassic. The Cheng’an intrusion is Ⅰ-type granite, formation temperature was 680±55 ℃, forming pressure was 0.21～0.30 GPa, and 6.93～9.90 km in depth. The formation mechanism of the Cheng’an intrusion is partially melted of the crustal material. |
| |
| Keywords: | |
| 本文献已被 万方数据 等数据库收录！ |
| 点击此处可从《地质科学》浏览原始摘要信息 |
| 点击此处可从《地质科学》下载免费的PDF全文 |
