Spatial-temporal framework of the Gangdese Orogenic Belt and its evolution.
Spatial-temporal framework of the Gangdese Orogenic Belt and its evolution.
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作者：
Pan Gui
冈底斯造山带的构造性质与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。本文以1：250000区调资料为依据，研究了冈底斯造山带的构造格架、划分及晚古生代-中生代的演化史。研究表明，冈底斯造山带的地质背景可由6个主要构造单元和18个次级构造单元很好地揭示出来。通过对不同构造单元的时空格架和相关岩浆记录的分析，认为冈底斯造山带不是一个简单的地块、陆段或地体，而是一个地体。但可能是一个复杂造山带在石炭-二叠纪、早-中三叠世、晚三叠世、早-中侏罗世、晚侏罗世-早白垩世和晚白垩世-始新世经历了六次弧形造山带向名为龙格尔-念青唐古拉的主轴的形成，以及与之相关的弧-陆、陆-陆碰撞，因此，冈底斯造山带的演化历史可能既受到班公湖怒江特提斯洋壳向南俯冲和雅鲁藏布江新特提斯洋壳向北俯冲的影响。强调指出，在增生弧形成的火山-岩浆弧是冈底斯斑岩型铜矿的最佳找矿方向，如安隆岗火山-岩浆弧、东恰共增生弧和桑日火山-岩浆弧等。
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,continent- continent collision,and ultimately finalized its profile at the late Cenozoic.It is therefore evident that the evolutional 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-magmatic 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.