砂砾岩物源供给能力定量评价——以济阳坳陷车镇凹陷郭局子洼陷为例

陡坡带砂砾岩具有扇体类型多、物源多、沉积速率快的特征，物源供给能力是控制砂砾岩规模和沉积体系的主要因素之一，其定量化表征一直是约束沉积体系研究的薄弱环节。为了解决砂砾岩物源供给能力的定量化表征问题，在砾岩含量、砂地比、岩性指数、隔夹层的发育程度、矿物含量和粒度分布研究的基础上，利用与物源供给速率成正比的参数和与物源供给速率成反比的参数进行量化加权平均，求取物源供给指数。结果表明，物源供给指数高值区主要分布在北部靠近埕南断层下降盘处，主要呈裙状沿大断层分布；物源供给能力控制砂砾岩规模，板式、铲式、阶梯式和坡坪式边界断层的砂砾岩分布模式和规模随着物源供给能力的变化而不同。物源供给能力与水深联合控制沉积相类型，随着水深和物源供给能力的变化，依次发育河流相、冲积扇、碳酸盐岩、三角洲、扇三角洲、浊积扇、湖底扇和近岸水下扇等沉积类型。

Quantitative evaluation of provenance supply capacity for sandy conglomerates: A case study of Guojuzi subsag in Chezhen Sag

Sandy conglomerates in steep slopes are characterized as various fan types,abundance of provenances,and high deposition rate,and the provenance supply capacity is one of the main factors controlling sandy conglomerate scale and its sedimentary system.However,the quantitative study of provenance supply is always a weak point which constrains the study of sedimentary system.In order to address the problem,we worked out the provenance supply index with weighted average of parameters which have positive and inverse relation with provenance supply rates.The calculation was based on the study of conglomerate content,ratio of sand and formation,lithologic index,development degree of interbed(frequency,thickness,percentage),mineral content,granularity distribution.And the results show that (1) the areas with high provenance supply indexes are mainly distributed in the north,close to the downthrown side of Chengnan fault,along large faults in the form of apron; (2) the provenance supply capacity determines the development scale of sandy conglome-rates:the distribution patterns and scales of sandy conglomerates beside plate-,shovel-,ladder- and slope-shaped boundary faults vary with the varying provenance supply capacities.In addition,a combination of the provenance supply capacity and depth of water controls the types of sedimentary facies.With the change of these two factors,the studied area has developed such sedimentary facies as fluvial facies,alluvial fan,carbonate rock,delta,fan delta,turbidite fan,sublacustrine fan,coastal subsea apron and so on.