辽河坳陷东部凹陷火成岩形成与分布的控制因素

The Control Factors of Igneous Rocks Formation and Distribution in Dongbu Sag in Liaohe Depression

从形成环境和构造演化等方面分析了辽河坳陷东部凹陷古近系火成岩的形成机理。认为本区各类火成岩属同源岩浆,未经历混染作用,粗面岩较玄武岩、辉绿岩结晶分异时间长。辉绿岩为渐新世晚期侵入体;沙三中段火山岩为水下喷发;沙三上段到东营组以水上喷发为主。岩浆活动主要受控于界西、驾掌寺、二界沟等断裂,始新世岩浆活动中心位于凹陷中段,渐新世位于南北两端;粗面岩主要发育于凹陷中南部沙三中段。

The formation mechanism of Eogene igneous rocks in Dongbu sag in Liaohe depression is analyzed in terms of forming environment and structural evolution. It is suggested that the various igneous rocks in this area belong to cogenetic magma without hybridism, and the crystal fractionation period of related trachyte is longer than those of basalt and diabase. The diabase is intrusive mass of Late Oligocene. The volcanic rock of the middle section of Sha-3 member features underwater eruption, while the upper section of Sha-3 member to Dongying formation is dominated by above-water eruption. The magma activity is mainly controlled by such faults as Jiexi, Jiazhangsi and Erjiegou, etc., and its center in Eocene is located in the middle section of Dongbu sag, the active center of magma in Oligocene is located in two sides of south and north Dongbu sag. The trachyte is mainly found in the midsection of Sha-3 member in south-central Dongbu sag.