张立雪, 陈爱清, 陈庆, 赖佩欣. 珠江口内伶仃洋晚第四纪黏土矿物组成特征及对源区气候变化的指示[J]. 海洋地质与第四纪地质, 2021, 41(5): 202-209. DOI: 10.16562/j.cnki.0256-1492.2020121002
引用本文: 张立雪, 陈爱清, 陈庆, 赖佩欣. 珠江口内伶仃洋晚第四纪黏土矿物组成特征及对源区气候变化的指示[J]. 海洋地质与第四纪地质, 2021, 41(5): 202-209. DOI: 10.16562/j.cnki.0256-1492.2020121002
ZHANG Lixue, CHEN Aiqing, CHEN Qing, LAI Peixin. Late Quaternary clay minerals in the inner Lingdingyang of the Pearl River Estuary, southern China: Implications for paleoclimate changes at the provenance[J]. Marine Geology & Quaternary Geology, 2021, 41(5): 202-209. DOI: 10.16562/j.cnki.0256-1492.2020121002
Citation: ZHANG Lixue, CHEN Aiqing, CHEN Qing, LAI Peixin. Late Quaternary clay minerals in the inner Lingdingyang of the Pearl River Estuary, southern China: Implications for paleoclimate changes at the provenance[J]. Marine Geology & Quaternary Geology, 2021, 41(5): 202-209. DOI: 10.16562/j.cnki.0256-1492.2020121002

珠江口内伶仃洋晚第四纪黏土矿物组成特征及对源区气候变化的指示

Late Quaternary clay minerals in the inner Lingdingyang of the Pearl River Estuary, southern China: Implications for paleoclimate changes at the provenance

  • 摘要: 黏土矿物组合和相对含量变化可反映源区地表风化过程,进而推断古气候的周期性变化,因此黏土矿物分析是古气候重建的重要手段之一。对珠江口内伶仃洋13-LD-ZK20钻孔晚第四纪沉积物中黏土矿物组成进行分析,结果显示黏土矿物主要为蒙脱石(含伊利石/蒙脱石无序混层),平均相对含量为49%,其次为伊利石、高岭石和绿泥石,平均相对含量分别为20%、19%和12%。伊利石化学指数较高(多数大于0.4),指示源区强烈的化学风化作用。珠江口内伶仃洋晚第四纪以来黏土矿物根据其相对含量变化和岩芯是否受成岩作用影响可分为4个阶段,指示西江源区气候总体暖-冷-暖的变化趋势。晚更新世第1阶段黏土矿物受成岩作用影响,不具古气候指示意义,第2阶段初期较为温暖,末期存在短期气候相对干冷阶段,可能与晚更新世末次冰盛期有关,第3阶段前期稍转暖。全新世(第3阶段后期和第4阶段)主要为温暖潮湿气候特征,并存在短期冷-暖波动。

     

    Abstract: Clay minerals are good indicators of paleoclimate changes , and therefore, clay mineral analysis is commonly used as a powerful tool for paleoclimate reconstruction. In this study, the assemblages and relative contents of clay minerals of the Late Quaternary sediments from the drill core 13-LD-ZK20 in the inner Lingdingyang of the Pearl River Estuary are analyzed. Our results suggest that the clay mineral assemblages are dominated by smectite on an average content of about 49% including illite-smectite mixed-layers clay mineral(R=0), followed by illite, kaolinite and chlorite on average of 20%, 19% and 12%, respectively. The high illite chemical weathering index is mostly greater than 0.4, which signify intense chemical weathering at the provenance. The Late Quaternary deposits of the region can be subdivided into four stages based on the composition of clay minerals and the diagenesis of sediments. It indicates a fluctuated paleoclimate pattern in the Xijiang drainage from warm, cold to warm again. Paleoclimate was unable to be reconstructed with clay minerals for the first stage of Late Pleistocene, due to strong diagenesis. In the second stage, it was warm in the beginning and turned cold by the end of the stage, most likely related to the Last Glacial Maximum. Then the paleoclimate slightly turned warmer in the early third stage. The paleoclimate in the Holocene was warm and humid with short periods of fluctuations.

     

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