黑龙江省东部佳木斯隆起多期隆升剥露历史的热年代学研究

摘要

黑龙江省东部佳木斯隆起是佳木斯地块重要组成部分,经历了多期板块碰撞闭合事件的影响,对其隆升剥露历史的热年代学研究有助于加深对东北各地块的碰撞拼贴历史以及古亚洲洋东端构造演化的认识.本文通过对黑龙江省东部佳木斯隆起老平岗花岗岩岩体中的锆石LA-ICP-MS、独居石Th-U-Pb化学法(CHIME)以及(钾长石、黑云母)40Ar-39 Ar法同位素年龄的测定,恢复了佳木斯隆起多期隆升剥露的构造热演化历史.研究结果显示佳木斯隆起晚三叠世之前主要存在三个隆升阶段,分别为早古生代早期(511～ 494Ma)和晚二叠世-中三叠世早期(260 ～ 240Ma)的快速隆升阶段以及期间的相对慢速隆升阶段.511 ～ 494Ma快速隆升阶段,冷却速率为11.76℃/Myr,隆升速率为0.294mm/a,17Myr隆升总幅度达5.00km,代表了佳木斯地块与松嫩地块的碰撞拼贴事件;494 ～ 260Ma相对慢速隆升阶段,冷却速率为1.51℃/Myr,隆升速率为0.038mm/a,234Myr隆升总幅度仅有8.80km;260 ～ 240Ma快速隆升阶段,冷却速率平均为8.44℃/Myr,隆升速度平均为0.21 1mm/a,20Myr隆升幅度平均达4.22km,该事件应与佳木斯地块与华北板块在晚二叠世-中三叠世的碰撞拼接事件有关.%Jiamusi uplift has experienced multi-period plate collision events in eastern Heilongjiang Province and is an important part of the Jiamusi massif.Thermochronology study on its uplift history will help to deepen the understanding of the history of the collision and amalgamation of Northeast Blocks and the tectonic evolution of the Paleo-Asian Ocean.In this paper,by using zircon LAICP-MS dating,monazite Th-U-Pb CHIME dating and K-feldspar,biotite 40Ar-39Ar dating for the samples collected from the granite of Laopinggang pluton in Jiamusi uplift,we recovered the tectonic thermal evolution history of the multi-stage cooling and uplift of the Jiamusi uplift.Calculation results show that the Jiamusi uplift experienced three stage uplifts:first stage in the Early Paleozoic (511 ～494Ma),the second stage from 494Ma to 260Ma and the third stage in the Late Permian to the Middle Triassic (260 ～ 240Ma).During the first stage in the Early Paleozoic,the cooling rate was 11.76℃/Myr and the uplift rate was 0.294mm/a,the total uplift amplitude reaches 5.00km,related to the collision event between the Jiamusi massif and the Songnen massif.During the second stage (from 494～260Ma),the uplift rate merely was 0.038mm/a and the corresponding cooling rate was 1.51℃/Myr.The total uplift amplitude was only 8.80km,indicating a stable period.During the third stage in the Late Permian to the Middle Triassic (260 ～240Ma),the cooling rate was 8.44℃/Myr and the uplift rate was 0.211mm/a,the total uplift amplitude averaged 4.22km,which should be related to the collision collage events between the Jiamusi massif and the North China Plate during the Late Permian to Middle Triassic.