辽河三角洲地区ZK2孔晚更新世晚期以来的碎屑矿物及其物源

DISTRIBUTION OF DETRITAL MINERALS IN THE CORE ZK2 AT THE LIAOHE DELTA AREA SINCE LATE PLEISTOCENE:IMPLICATION FOR PROVENANCE

对辽河三角洲地区ZK2孔（孔深0~32m）的92个沉积物样品中碎屑矿物进行鉴定和统计分析,结果显示：所有样品中轻矿物质量百分含量均超过95%,以石英和长石为主;重矿物质量百分平均含量仅为0.82%,以普通角闪石、绿帘石、阳起石、石榴子石、赤-褐铁矿和自生黄铁矿等为主。轻矿物组合和含量在地层中变化相对稳定,而重矿物组合和含量则在地层中变化显著。以所有重矿物各自百分含量为变量,利用Tilia软件进行有序聚类,自下而上可以划分出4个不同的重矿物组合带,这些组合带分别大致对应河道、湖沼、潮坪-浅海、三角洲4个沉积相环境。研究表明：不同组合带中各重矿物百分含量的变化与沉积环境紧密相关,其中沉积环境中水动力条件和离河口的远近,是控制重矿物中稳定矿物特别是金属矿物变化的主导因素。ZK2孔自晚更新世晚期以来沉积物源没有发生明显的变化,其主要物源来自辽河,其次为大辽河。

A total of 92 samples taken from the core ZK2（depth 0-32m）at the Liaohe Delta are analyzed for detrital minerals.It is revealed that the mass percentages of light minerals,which mainly consist of quartz and feldspar,are above 95%in these samples.The average mass percentage of heavy minerals is only about 0.82%,which include hornblende,epidote,actinolite,garnet,hematite,limonite and authigenic pyrite.The assemblages and percentage compositions of light minerals remain relatively stable while those of heavy minerals vary significantly since Late Pleistocene.According to the order cluster analysis on all detectable heavy minerals by software Tilia,we divide heavy minerals into 4assemblages for the core ZK2 since Late Pleistocene,which approximately correspond to 4sedimentary facies,namely river channel,marsh,tidal flat-shallow sea and deltaic environments.The research suggests that the percentage composition of each heavy mineral is mainly dependent upon the depositional environment,the sedimentary hydrodynamic conditions and the distance from estuary,especially for metallic minerals.There is no significant change in provenance for the sediments deposited since Late Pleistocene.The sediments were mainly derived from the Liaohe River and secondary the Daliaohe River.