摘要
皮山县克里阳剖面是塔南坳陷带中—新生界发育最为完整、变形现象最具代表性的剖面。系统的磷灰石裂变径迹分析表明,上白垩统—中新统砂岩样品的平均径迹年龄均大于相应的地层时代,样品的P(x2)大部分小于0.1%,说明不属于同组年龄。磷灰石单颗粒径迹年龄最大值为180～190Ma,最小年龄为10～20Ma,峰值年龄为80～90Ma和50～70Ma,磷灰石的平均径迹长度为(10.82±2.01)～(9.06±2.01)μm。径迹记录表明晚白垩世至中新世时期,沉积层的主体部分并未下沉到达磷灰石的退火带深度而导致早期径迹记录的全部消失。说明新生代时期,特别是新近纪以来,尽管西昆仑造山带存在强烈的热构造作用,山前坳陷带也发生了构造沉降,但并不存在塔里木地块向西昆仑山体的大规模的陆内俯冲作用,总体看塔南坳陷带的下插深度并未超过7km(磷灰石的退火带深度)。
The Kiliyang section, Pishan County, Xinjiang, is a section with the most complete Meso-Cenozoic successions and most typical deformation phenomenon in the southern Tarim depression. Systematic apatite fission-track analysis indicates that all the mean fission-track ages of Upper Cretaceous-Miocene sandstone samples are older than their corresponding stratigraphic ages. Most of the P（x^2） values of the samples are 〈0.1%, suggesting that the ages do not belong to the same group. The single-grain apatite fission-track ages have a maximum of 180-190 Ma and a minimum of 10-20/Via with peak ages of 80-90/Via and 50-70 Ma. The mean apatite fission-track lengths are 10.82±2.01 to 9.06±2.01μm. Fission-track records indicate that during the Late Cretaceous to Miocene the sediments did not sink to the depth of the apatite-annealing zone, thus leading to disappearance of all the earlier fission-track records. This suggests that large-scale subduction of the Tarim block beneath the West Kunlun Mountains has not taken place during the Cenozoic, especially since the Neogene, though there occurred strong thermal structural processes in the West Kunlun orogenic belt and also structural subsidence in the piedmont depression. The underthrusting depth of the southern Tarim depression generally does not exceed 7 km （depth of the apatite-annealing zone）. The apatite fission-track study of the sediments in the southern Tarim depression provides a new research concept and method for solving the relation between the West Kunlun orogenic belt and Tarim block.
出处
《地质通报》
CAS
CSCD
北大核心
2007年第10期1245-1251,共7页
Geological Bulletin of China
基金
国家自然科学基金项目(编号:19972072)
国土资源部科技项目(编号:2000101)
国土资源部大陆动力学开放实验室项目资助
关键词
新疆
塔南坳陷带
磷灰石
裂变径迹
退火带
俯冲
Xinjiang
southern Tarim depression
apatite
fission track
annealing zone
subduction
