东昆仑南坡埃坑北花岗斑岩的成岩年龄及其地质意义

Diagenetic Age of the Granite Porphyry in Northern Aikengdelesite South of East Kunlun and Geological Implications

东昆仑南坡埃坑北花岗斑岩位于青海省都兰县诺木洪镇南八宝滩以南、马尔争以北的埃坑德勒斯特沟中游一带埃坑铜钼矿带的北矿区,其大地构造位置属于东昆仑南坡俯冲增生杂岩带中生代弧后前陆盆地,是古特提斯北部活动陆缘的南部边缘区域,也是广义的东昆仑岩浆弧构造带的组成部分。该斑岩体是埃坑铜钼矿的围岩和成矿母岩,花岗斑岩体的LA-ICP-MS锆石U-Pb成岩年龄为242±1.2Ma,推测斑岩型铜钼矿成矿时代应为中三叠世—晚三叠世早期。这一成果对该带斑岩型铜钼矿的找矿勘查工作有一定指导意义。

The granite porphyry in northern Aikengdelsite on the south slope of East Kunlun is located in the north mining area of Aikengdelsite cop- per- molybdenum ore belt, middle Aikengdelsite region, south of Babaotan, and north of Ma＇ erzheng, Nomuhong Town, Dulan County, Qinghai Prov- ince. In tectonic setting, it is in a back - arc foreland basin of Mesozoic with subduction - accretion complex belts on the southern slope of East Kunlun, as well as the south edge of the northern Paleo - Tethys active continental margin. It is also part of the generalized magma are tectonic zone of East Kun- lun. The porphyry mass is the surrounding rock of Aikengdelsite copper - molybdenum ores and mineralization mother rock. By LA - ICP - MS SHRIMP zircon U - Pb dating, the granitic porphyry mass has the diagenetics age of 242 ± 1.2Ma. It is inferred that the metallogenetic epoch of the porphyry - type copper - molybdenum ores is in Middle Triassic and early Late Triassic. This result will provide some guidance for geological exploration of porphyry - type copper - molybdenum ores in this area.