东海西湖凹陷碎屑岩物源聚类分析

    CLUSTERING ANALYSIS OF CLASTIC ROCKS FOR PROVENANCE IN XIHU DEPRESSION

    • 摘要: 重矿物聚类分析是研究沉积物源的重要手段。通过对东海陆架西湖凹陷古近系宝石组至新近系龙井组32口钻井900多个砂岩样品的重矿物Q型、R型聚类和ZTR趋势线等分析认为:西湖凹陷碎屑岩主要具有2种不同性质的物源,其沉积区分别位于凹陷北部和中南部。凹陷中南部可以进一步划分出5个次级母岩分区,分别位于西斜坡带中部、西次凹北部和南部、中央反转构造带北部和南部。西湖凹陷北部碎屑岩母岩主要为酸性岩浆岩和变质岩,中南部碎屑岩母岩主要为变质岩,岩浆岩次之。西湖凹陷北部沉积物源主要为虎皮礁隆起带;而中南部沉积物源主要为海礁隆起和钓鱼岛隆褶带,这2个物源区母岩岩性类似。

       

      Abstract: The clustering analysis of heavy minerals is an important tool for provenance study. According to the Q-type and R-type of heavy mineral clustering and distribution pattern of ZTR contour line for more than 900 samples collected from the Xihu Depression, we discussed hereby the provenance and attributes of the clastic rocks in the Xihu Depression. The research reveals that there are two distinct sediment sources, which correspond to deposits in the north of the depression and in the middle south region. There are five sub-areas in the middle south region, i.e. the sub-areas located in the middle western slope zone, the north of and the south of western secondary sag, the north of and the south of central inverted structure zone respectively. The provenance in the western slope zone consists of two types of rocks, i.e. acid igneous rocks and metamorphic rocks, while the provenance of middle south region is dominated by metamorphic rocks with igneous rocks as the second. The heavy minerals in the northern Xihu Depression come from the Hupijiao Uplift belt and in the middle and south region they are mainly from the Haijiao and Diaoyudao Uplift belt. The two types of provenance are similar in nature.

       

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