Provenance Study of Holocene Sediments in Subei Coastal Plain ——Comparison between elemental geochemistry and heavy mineral methods
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摘要: 运用元素地球化学与重矿物方法对苏北滨海平原全新世沉积物物源进行的比较研究表明，沉积物形成主要由长江与黄河提供物质来源，且又以黄河物源为主。全新世早期长江物质对本区影响范围大于黄河，黄河供给泥沙量较少，对本区影响主要在北部、中部地区。全新世最大海侵之后，黄河曾由苏北入海并携带了大量泥沙，其影响范围明显大于长江，长江仅由狭窄的汊道提供有限的物质而影响范围较小。最近2000年来本区沉积物物源主要由黄河提供。分析表明元素地球化学方法在沉积物物源判别时，可有效的避免水动力因素影响，而相对重矿物方法取得较好的效果。Abstract: Element geochemical and heavy mineral methods are applied to study provenance of Holocene sediments in Subei coastal plain. Based on core analyses, that sedimentary strata developed in Subei coastal plain during Holocene mainly include littoral facies, offshore-neritic facies and tidal flat facies from the lower part to the upper part. The authors firstly resarched elemental and heavy mineral compositions of the Changjaing and the Huanghe sediemnts, and study shows there are obvious differences between both sediments. Some elements and heavy minerals can be applied to trace the Changjiang and the Huanghe sediments and study the diffusions and mixture of both rivers in coastal zones. And then, elemental and detrital mineral compositions of Holocene sediments from four drilling cores in Subei coastal plain are determined in detail. Analyses reveal that the Huanghe River is the dominant provenance and supplied more matters for formation of Holocene sediments than the Changjiang River. During early Holocene, influence of the Changjiang matter exceeded that of the Huanghe matter. After the maximal transgression in Holocene, the Huanghe River arrived the South Yellow Sea and carried abundant sediment, and the Changjiang River supplied limited matter by a narrow distributary and its influence was small. During the last two thousand years, sediments of this area were mainly from the Huanghe River. Study also shows that elemental geochemical method is more useful than heavy mineral method in provenance discrimination because the former can effectively avoid the influence of hydraulic sorting.
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Key words:
- provenance /
- Subei coastal plain /
- Holocene /
- elemental geochemistry /
- heavy mineral
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