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| 1 | Tectonic evolution of the Dabashan orocline, central China: Insights from the superposed folds in the eastern Dabashan foreland显示文摘The Dabashan orocline is situated in the northwestern margin of the central Yangtze block,central China.Previous studies have defned the orthogonal superposed folds growing in its central-western segment thereby confrming its two-stage tectonic evolution history.Geological mapping has revealed that more types of superposed folds have developed in the eastern segment of the orocline,which probably provides more clues for probing the structure and tectonic history of the Dabashan orocline.In this paper,based on geological mapping,structural measurements and analyses of deformation,we have identifed three groups of folds with different trends(e.g.NW-,NE-and nearly E-trending folds)and three types of structural patterns of superposed folds in the eastern Dabashan foreland(e.g.syn-axial,oblique,and conjunctional superposed folds).In combination with geochronological data,we propose that the synaxial superposed folds are due to two stages of wNeS shortening in the west and north of the Shennongjia massif,and that oblique superposed folds have been resulted from the superposition of the NW-and NE-trending folds onto the early ~E-W folds in the east of the Shennongjia massif in the late Jurassic to early Cretaceous.The conjunctional folds are composed of the NW-and NE-trending folds,corresponding to the regional-scale dual-orocline in the eastern Sichuan as a result of the southwestward expansion of the Dabashan foreland during late Jurassic to early Cretaceous,coeval with the northwestward propagation of the Xuefengshan foreland.Integration of the structure and geochronology of the belt shows that the Dabashan orocline is a combined deformation belt primarily experiencing a twostage tectonic evolution history in Mesozoic,initiation of the Dabashan orocline as a foreland basin along the front of the Qinling orogen in late Triassic to early Jurassic due to collisional orogeny,and the fnal formation of the Dabashan orocline owing to the southwestward propagation of the Qinling orogen during late Jurassic to early Cretaceous intra-continental orogeny.Our studies provide some evidences for understanding the structure and deformation of the Dabashan orocline. | Wei Shi Jianhua Li Mi Tian Guoli Wu | 2013 | Geoscience Frontiers2013，4，6： | 12 |
| 2 | Zircon Geochronology and Trace Element Geochemistry from the Xiaozhen Copper Deposit, North Daba Mountain: Constraints on Albitites Petrogenesis显示文摘Albitite often accompanies with various metal and gem mineral deposits and a large number of occurrences have been reported globally, including the South Qinling orogen, China. The Xiaozhen copper deposit is a typical deposit in the North Daba Mountain area of the South Qinling orogen whose distribution is controlled by albitite veins and fractures. As there are few studies on the petrogenesis of albitite in Xiaozhen copper deposit, this paper focuses on the petrogenesis of albitite and its mineralization age. Detailed fieldwork and mineral microscopic observations initially suggest that albitite from the Xiaozhen copper deposit is igneous in origin. Further zircon trace element geochemistry studies indicate that these zircons have high Th/U ratios(>0.5), low La content, high(Sm/La)N and Ce/Ce*values, and a strong negative Eu anomaly, which are commonly seen in magmatic zircons. The chondrite–normalized rare earth element(REE) patterns are consistent with magmatic zircons from throughout the world, and they fall within or near the field of magmatic zircons on discriminant diagrams. The calculated average apparent Ti–in–zircon temperature for young zircons is 780°C, consistent with magmatic zircon crystallization temperatures. Therefore, zircon geochemistry indicates that the albitite origin is magmatic. SIMS U–Pb dating on nine magmatic zircons yielded a concordia age of 154.8±2.2 Ma, which represents the formation of albitite and the metallogenic age. More importantly, it is consistent with the ages of Yanshanian magmatism and metallogenesis in the South Qinling orogen, so formation of the Xiaozhen copper deposit may be a closely related geological event. | WANG Gang WANG Zongqi ZHANG Yingli WANG Kunming | 2014 | Acta Geologica Sinica(English Edition)2014，88，1： | 3 |
| 3 | 四川盆地北缘下侏罗统白田坝组砾岩发育特征及对南大巴山隆升时间的制约显示文摘通过大量详细的野外实际测量工作发现,四川盆地北缘下侏罗统白田坝组底部普遍为沉积砾岩。根据砾岩不同沉积特征将其划分为米仓山砾岩带、大巴山西段砾岩带和大巴山东段砾岩带。米仓山和大巴山西段砾岩带均为砾质冲积扇沉积,大巴山东段砾岩带相变为曲流河滞留沉积。而在重庆紫水、温泉和长滩一带缺乏砾岩沉积。依据砾岩沉积特征和沉积体系展布,从沉积学角度限定了南大巴山隆升时间为早侏罗世之后。白田坝组砾岩沉积不受南大巴山逆冲作用控制。大巴山山前砾岩在沉积之后被后期隆升的南大巴山掩盖或改造,呈现出现今的'残余'面貌。四川盆地北缘早侏罗世冲积扇砾岩带应向东延伸展布且盆地北缘分布范围比现今大得多,可能应跨过大巴山继续向东延至中扬子地区。 | 钱涛 刘少峰 王宗秀 李王鹏 陈心路 | 2016 | 中国科技论文2016，11，21： | 1 |
| 4 | 四川盆地盆缘前陆逆冲带的复合与联合扩展研究综述显示文摘前陆逆冲带扩展方式是理解造山带生长的关键。四川盆地东缘、北缘和西缘分别发育不同时代和不同构造背景下形成的武陵山-华蓥山、大巴山和龙门山前陆逆冲带,前人对他们的结构和构造运动学进行了详尽的研究。本文在总结这些研究的基础上,揭示武陵山-华蓥山、大巴山和龙门山三条前陆逆冲带的结构分带均表现为从厚皮逆冲构造至薄皮逆冲构造组合的变化,构造解析表明结构分带是断层-褶皱关系主导的指向前陆盆地方向共轴递进扩展作用的结果。同时,在前陆逆冲带扩展分析基础上,总结了四川盆地盆缘共轴扩展、非共轴叠加复合扩展和联合构造扩展三种前陆逆冲带扩展方式。结合阿巴拉契亚、科迪勒拉、阿尔卑斯、喜马拉雅、比利牛斯山等经典造山带前陆逆冲带扩展的研究现状,提出前陆逆冲带扩展研究中存在古构造应力场的σ2悖论、应力-应变(σ-ε)关系难以建立和系统不平衡等问题,并认为这些问题是未来定量化约束前陆逆冲带扩展,进而解决造山带生长构造动力学研究的主要挑战。 | 颜丹平 邱亮 孙铭 周志成 孔若颜 张已 王为 宋华杰 孔霏 都超 林霄晗 | 2022 | 地质学报2022，96，10： | 0 |
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