摘要
冈底斯带的构造属性及其构造单元划分一直是青藏高原基础地质研究中最热门的科学问题之一。根据新的地质调查资料、研究成果并结合我们的分析数据,对冈底斯带的地质构造格局进行了厘定和划分,讨论了冈底斯带晚古生代-中生代的构造演化历史。冈底斯带可划分为6类不同的构造单元和18个次级单元,这些不同级别的构造划分较为全面准确地概括了冈底斯带的地质面貌。通过对不同构造单元时空结构的剖析和对相关火山岩浆作用记录的分析,认为冈底斯带不是简单的地块、陆块或地体,而很可能是以隆格尔-念青唐古拉为主轴,经历石炭-二叠纪、早中三叠世、晚三叠世、早中侏罗世、晚侏罗世-早白垩世、晚白垩世-始新世六次造弧增生作用和相关的弧-陆、陆-陆碰撞作用并最终定型于新生代晚期的复合造山带,并在此基础上,提出冈底斯带的构造演化很可能受班公湖-怒江特提斯洋向南、雅鲁藏布洋向北的双向俯冲的制约。强调以增生弧为背景的火山岩浆弧(如昂龙岗日火山岩浆弧、东恰错弧、桑日火山弧)可能是冈底斯地区寻找斑岩铜矿的最佳有利场所。
The tectonic nature and subdivision of Gangdese Orogenic Belt is always one of the hottest scientific problems related to fundamental geology of Qinghai-Tibetan Plateau. The tectonic framework, subdivision and the Late Paleozoic-Mesozoic evolutional history of Gangdese Orogenic Belt have been studied based on regional geological survey （ 1：250000 ） and our data. Our study shows that the geological context of Gangdese can be well revealed by six major tectonic units and eighteen secondary units. Based on the analysis for spatial-temporal framework of different tectonic units and related magmatic records, we suggest that the Gangdese Orogenic Belt is not a simply block or continental segment, or terrane, but likely a complex orogenic belt experienced six arc-forming accretionary to a principal axis named Long＇ge＇er-Nyainqentanglha at Carboniferous-Permian, Early-Middle Triassic, Late Triassic, Early-Middle Jurassic, Late Jurassic-Early Cretaceous and Late Cretaceous-Eocene, as well as related arc-continent, continentcontinent collision, and ultimately finalized its profile at the late Cenozoic. It is therefore evident that the evolutlonal history of Gangdese Orogenic Belt may have influenced from both the southward subduction of Bangong Co-Nujiang Tethyan Ocean crust and northward subduction of Yarlung Zangbo neo-Tethyan Ocean crust. It is emphasized that volcanic-magrnatic arc formed at accretionary arc has the best potential for porphyry copper deposit in Gangdese, as revealed by Anglonggangri volcanic-magmatic arc, Dongqia Co accretionary arc and Sangri volcanic-magmatic arc, etc.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第3期521-533,共13页
Acta Petrologica Sinica
基金
国家重点基础研究发展规划项目(2002CB412609)
国家自然科学基金(40503005
40572051
40473020)
中国地质调查局"青藏高原南部空白区基础地质综合研究"项目(200313000025)联合资助。
关键词
演化历史
构造单元
双向俯冲
造弧作用
冈底斯造山带
Evolutional history, Tectonic unit, Bi-directional subduction, Arc-forming, Gangdese Orogenic Belt
