The bedding shear structures of the Lhasa Riduo basin in the late Jurassic-early Cretaceous, and it’s geological significances
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摘要: 拉萨-日多盆地中存在不同构造体制下的两期构造变形。本文运用构造解析法，对盆地中新厘定出的晚侏罗世—早白垩世期间普遍存在的以横向构造置换为主的顺层剪切构造群落进行详细调查研究，划分出顺层剪切作用下形成的顺层韧性剪切带、顺层掩卧褶皱、顺层面理与拉伸线理、粘滞性石香肠及同构造淡色脉等不同构造样式。结合石英显微构造变形及EBSD组构分析，认为顺层剪切构造中石英以中低温组构（400~550℃）的底面和菱面滑移系为主，早期经历了中高温组构（550℃~650℃）的柱面滑移变形，并叠加了后期低温组构的（﹤400℃）底面滑移变形，总体反映了中等及中低温条件下的剪切变形作用。初步建立了拉萨-日多盆地中的顺层剪切构造变形机制的一种可能模式，即伸展体制下大规模的水平分层剪切作用，认为晚侏罗世—早白垩世时期拉萨-日多盆地为伸展盆地。Abstract: Located in southern Gangdise volcanic arc, the late Jurassic-early Cretaceous Lhasa-Riduo basin, Tibet, experienced two deformation stages under different tectonic settings. Based on detailed geological investigation, the bedding shear structures such as bedding recumbent folds, bedding foliations, stretching lineations, viscous boudinages and syntectonic leucocratic veins are recognized in this paper. Studies on microstructural deformation and EBSD analyses indicate that deformations of quartzs in bedding shear zones were currently dominated by basal glides and rhombohedral glides,with the mid-low temperature(400℃~500℃)fabrics, but previously, they experienced deformation stages of the medium-high temperature fabric (550℃~650℃) prismatic glide and the late low-temperature fabric (<400℃) basal glide .The authors suggest a possible model for the bedding shear structures in the Lhasa-Riduo Basin. It is believed that the bedding shear structures in the Lhasa-Riduo basin were formed by a large-scale horizontal and stratified shear action which was under the extensional tectonic setting during the Late Jurassic to the Early Cretaceous.
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[1] 南征兵,李永铁,郭祖军.青藏高原重点沉积盆地油气勘探前景展望[J].地质科技情报,2008,(27)4:63-68. [2] 鲁兵,李永铁,刘忠,等.青藏高原的盆地形成与分类[J].石油学报,2000,2(12):21-26. [3] 余光明,王成善,张哨楠.西藏地区特提斯中生代沉积特征及沉积盆地演化[J].中国科学B辑,1989(9):982-990. [4] 马元,许志琴,李广伟,等.藏南冈底斯白垩纪弧后盆地的地壳变形及初始高原的形成[J].岩石学报,2017,33(12):3862-3872. [5] 彭勇民,姚鹏,李金高.西藏甲马弧内盆地的形成演化[J].沉积与特提斯地质,2001,21(2):101-107. [6] Zhang K J.Cretaceouspalaeogeography of Tibet and adjacent areas (China):tectonic implications[J]. Cretaceous Research,2000,21(1):23-33.
[7] Zhang K J.Secular geochemical variations of the Lower Cretaceous silici clastic rocks from central Tibet (China) indicate a tectonic transition from continental collision to back-arc rifting[J].Earth and Planetary Science Letters,2004,229(1-2):73-89.
[8] Kapp P,Yin A,Manning C E,et al. Tectonic evolution of the early Mesozoic blue schist-bearing Qiangtang metamorphic belt,central Tibet[J].Tectonics,2003,22(4):1-17.
[9] Leier A L,De Celles P G,Kapp P,et al.The Takena Formation of the Lhasa terrane, southern Tibet:The record of a Late Cretaceous retroarc foreland basin[J]. Geological Society of America Bulletin, 2007,119(1-2):31-48.
[10] 王立全,潘桂堂,丁俊,等.青藏高原及邻区地质图及说明书(1:1500000)[M].北京:地质出版社,2013,9-48. [11] 潘桂棠,莫宣学,侯增谦,等.冈底斯造山带的时空结构及演化[J].岩石学报,2006,(3):3-15. [12] 朱弟成,赵志丹,牛耀龄.拉萨地体的起源和古生代构造演化[J]. 高校地质学报,2012,18(1):1-15. [13] 韩奎,周斌,乔新星,等.拉萨地块南缘日多地区叶巴组火山岩地球化学、年代学、锆石Lu-Hf同位素特征及其地质意义[J].地质通报,2018,37(8):1554-1570. [14] 熊秋伟,陈建林,许继峰,等.拉萨地块南部得明顶地区叶巴组火山岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其成因[J].地质通报,2015,34(9):1645-1655. [15] Wang C,Ding L,Liu Z C,et al. Early Cretaceous bimodal volcanic rocks in the southern Lhasa terrane,south Tibet:Age,petrogenesis and tectonic implications[J]. Lithos,2017,268:260-273.
[16] 叶丽娟,赵志丹,刘栋,等.西藏南木林晚白垩世辉绿岩与花岗质脉岩成因及其揭示的伸展背景[J]. 岩石学报,2015,31(5):1298-1312. [17] 周斌,韩奎,潘亮,等.西藏日多地区1:5万区域地质调查成果报告[R].西安:陕西省地质调查中心,2019.1-334. [18] 徐海军,金淑燕,郑伯让.岩石组构学研究的最新技术-电子背散射衍射(EBSD)[J].现代地质,2007,(02):213-225. [19] 张宏飞,徐旺春,郭建秋,等.冈底斯南缘变形花岗岩锆石U-Pb年龄和Hf同位素组成:新特提斯洋早侏罗世俯冲作用的证据[J].岩石学报,2007,23(6):1347-1353. [20] 邱检生,王睿强,赵姣龙,等.冈底斯中段早侏罗世辉长岩-花岗岩杂岩体成因及其对新特提斯构造演化的启示:以日喀则东嘎岩体为例[J].岩石学报,2015,31(12):3569-3580. [21] Meng Y K,Xu Z Q,Santosh M,et al.Late Triassic crustal growth in southern Tibet:Evidence from the Gandese magmatic belt[J].Gondwana Research,2015,37:449-464.
[22] 潘亮,周斌,韩奎,等.日多中生代沉积盆地的性质及其形成演化[J].矿产勘查,2018,9(9):104-113. [23] Mattauer M.Les deformation des materiaux de lecorce terrestre[M]. Paris:Herman,1980.
[24] 单文琅,宋鸿林,付昭仁,等.构造变形分析的理论、方法和实践[M].武汉:中国地质大学出版社,1991.93-116. [25] 单文琅,傅昭仁,宋鸿林.大陆韧性伸展构造系统解析纲要[J]. 地球科学-中国地质大学学报,1991,16(5):515-522. [26] 马杏垣,索书田. 论滑覆及岩石圈内多层次滑脱构造[J].地质学报,1984,(3):205-213. [27] 宋鸿林,单文琅.剥离断层、板块内近水平韧性剪切带与伸展构造[J].地球科学,1987,12(5):535-541. [28] 曹忠权,申旭辉,阎永利,等.拉萨盆地曲水一夺底剖面大地电磁测深研究[J].地球物理学报,2010, 53(5):1173-1178.
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