Origin of Mineral Series of Anhydrite Limonite Kaolinite Dolomite and Its Paleoclimate Significance：An Example f rom Zhujiang Formation of Well LH 3 in Eastern Pearl River Mouth Basin
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维普
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珠江组是珠江口盆地东部地区的主要产层，L H 3井23．8～18．5 M a的下珠江组的取心段，包括浅海陆源碎屑岩，碳酸盐以及碎屑岩碳酸盐混积岩，呈现一套硬石膏褐铁矿高岭石白云石的矿物序列，且这套矿物序列在该井附近的同时代地层中也有发育，但完整程度有别。通过对这些矿物物质来源、形成原因以及形成时间的探讨，认为它们形成于沉积时期或者同生成岩阶段或准同生沉积期，均反映了氧化甚至暴露的沉积环境。同时也能提供气候的湿度方面信息，硬石膏以及白云石的发育反映气候干旱，而褐铁矿以及高岭石发育段反映了气候较潮湿。综合孢粉、同位素资料分析认为，取心段在珠江组下段沉积期的气候经历了炎热干旱温暖潮湿炎热干旱的变化过程。
Zhujiang Formation is the provincial reservoir in Pearl River Mouth basin ,and the cored section of Lower Zhujiang Formation (deposited from 23 .8 to 18 .5 Ma) of well LH 3 in eastern basin , consisting of terriclastic and carbonate rocks as well as mixed terriclastic-carbonate rocks ,demonstrates a mineral series of anhydrite-limonite-kaolinite-dolomite from bottom to top ,which also exist in adjacent wells ,while the abundances are different .After the analysis of the material sources ,formatting time and geological mechanism of these minerals ,the authors draw the conclusion that all of the minerals formed in depositional of syn-diagenetic or pene-contemporaneous stage ,w hich reflects oxidized or even exposed environments during their formation . Furthermore , the mineral association can provide humidity information ,as anhydrite and dolomite reflect the arid climate ,while limonite and kaolinite indicate humid climate .After the integration of sponge and pollen data ,carbon-oxygen isotopic data from neighbor wells ,the authors know that the climate during the Lower Zhujiang Formation deposition have changed from arid and hot to humid and warm ,then back to arid and hot again .
Pearl River Mouth basinminerals seriesdiagenesispaleoclimatedepositional system
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NSTL
维普
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