Yuanzineng kexue jishu (Dec 2022)
new evidence of tectonic event of south narimalahei area in eastern kunlun mountain constrained by apatite fission track
Abstract
Narimalaheinan copper deposit is located in the east section of East Kunlun. Its ore forming belt belongs to Qimantage Dulan Variscan polymetallic metallogenic belt. The study of its tectonic activity provides scientific data for subsequent mineral exploration and the preservation and change of the deposit. Apatite fission track chronology method was used to explore the thermal chronological constraints of tectonic activities in different stages in the area, and the uplift rate and amount were quantitatively calculated. The ages of six apatite samples obtained in this study were (64±4), (59±3), (54±4), (57±4), (51±4), (57±4) Ma, P(χ2)＞5%, indicating a single thermal event reaction. The age of apatite samples is positively correlated with the elevation, indicating that the study area is uplifted as a whole by tectonic activities. The fission track length of apatite sample is (106±19)(123±17) μm. The track length is large, and the sample age value has a positive correlation with the track length, indicating that the older samples have a shorter residence time in the return zone and are less affected by later thermal events. The cooling curve simulation results show that the study area has experienced three stages of evolution: rapid uplift, stable uplift and rapid uplift, and the corresponding uplift amounts are 1 429, 285 and 1 571 m respectively. The thermal history in the area was simulated by HeFTy software, the results show that the thermal evolution in the region is divided into three stages. In the first stage (8065 Ma), the uplift rate is 0095 mm/a and the uplift amount is 1 429 m. There is a rapid uplift event, which records the beginning of the closure of the Yarlung Zangbo ocean and the beginning of the collision between India and Asia. In the second stage (6515 Ma) the uplift rate is 0006 mm/a and the uplift volume is 285 m, which occurrs slow uplift and records the collision event between the Indian plate and the Eurasian plate. In the third stage (15 Ma to now), the uplift rate is 0105 mm/a and the uplift volume is 1 571 m, which records the post collision between the Indian plate and the Eurasian plate, resulting in the rapid uplift of the study area at 15 Ma.
