川西若尔盖地区中-新生代构造-热事件及其年代学框架

Tectono-Thermal Events and Chronological Framework in Zoige and Its Periphery

通过对川陕甘矿产资源"金三角"地区若尔盖及其周缘沉积建造特征、构造-热事件放射性年代学测试以及磷灰石裂变径迹热年代学测试等综合研究表明,若尔盖地区自印支末期以来,共发生了7次构造-热事件:(1)卡尼末-诺利初期构造-热事件(D1);(2)早侏罗世(200～180Ma)构造-热事件(D2);(3)晚侏罗-早白垩世(160～140Ma)构造-热事件(D3);(4)早白垩世(130～110Ma)构造-热事件(D4);(5)古新世(70～60Ma)构造-热事件(D5);(6)50～40Ma构造-热事件(D6);(7)20Ma左右构造-热事件(D7).其中D1期构造-热事件为若尔盖地区主褶皱造山构造运动,基本奠定若尔盖及其周缘地区区域构造格架;D2、D4为区域关键构造变革期,导致构造-热体制(压性与张性)的关键转换,对区域成矿具有重要意义;最晚期事件(D7期)为青藏高原东北缘高原地貌定型期.

Based on analysis of the sedimentary features, fission track data, ESR dating and Ar-Ar dating, we argue that there are seven tectono-thermal events in Zoige and its periphery from the Late Triassic. The first tectono-thermal events （D1） took place at the end of the Carnian to the beginning of the Norian stage to form the tectonic framework of Zoige area; the second （D2） and the fourth （D4） tectono-thermal events took place at the early of Jurassic （200-180 Ma） and 130-110 Ma, respectively. They are the key change events in tectonic framework at each time. The seventh （D7） took place at the early of Miocene （-20 Ma）, as the most important tectonic event to form the Tibet Plateau. The other three events （D3, D5, D6 ） took place at 160--140 Ma, 70--60 Ma,50--40 Ma, respectively.