临清坳陷东部三叠系沉积岩地球化学特征及构造意义

GEOCHEMISTRY OF TRIASSIC DEPOSITS IN EASTERN LINQING DEPRESSION AND ITS TECTONIC SIGNIFICANCE

碎屑沉积岩的物质组成对其形成的构造背景具有重要的指示作用。通过对临清坳陷东部三叠系碎屑沉积岩样品地球化学主量和微量元素分析表明:三叠系岩石样品主要为成熟度较低的杂砂岩和长石砂岩;碎屑沉积岩的母岩总体上与大陆地壳组成基本一致,原岩以沉积岩和花岗岩为主;临清坳陷东部中生代早—中三叠世处于靠近大陆岛弧的活动大陆边缘构造环境,其动力学机制与早期秦岭洋壳向华北板块俯冲、晚期扬子板块和华北板块碰撞作用有关。研究结果为确定三叠纪时期华北东部南侧的构造环境提供了地球化学方面的证据。

The mineral composition of clastic sedimentary rocks is an important indicator to tectonic setting of the sediments.In this paper,we analyzed the major and trace elements of the Triassic clastic deposits sampled from the Eastern Linqing Depression.Results show that,the Triassic samples are mainly greywacke and arkose with low maturity.The parent rock of the clastic sedimentary rock is consistent with continental crust in general which mainly are sedimentary rocks and granite,and the Eastern Linqing Depression was a tectonic environment of active continental margin close to the continental island arc in Early-Middle Triassic Epoch.The dynamic mechanism can be connected to the subduction of the Qinling ocean crust beneath the North China plate in early stage and the collision between the Yangtze plate and North China plate later on.This study provides the geochemical evidence for determining the tectonic environment of the south side to the eastern North China in Triassic period.