孙金龙, 徐辉龙, 丘学林, 沈建伟, 詹文欢. 粤东海山岛全新世硬壳灰岩的沉积特征及其岩石学意义[J]. 海洋地质与第四纪地质, 2006, 26(6): 45-53.
引用本文: 孙金龙, 徐辉龙, 丘学林, 沈建伟, 詹文欢. 粤东海山岛全新世硬壳灰岩的沉积特征及其岩石学意义[J]. 海洋地质与第四纪地质, 2006, 26(6): 45-53.
SUN Jin-long, XU Hui-long, QIU Xue-lin, SHEN Jian-wei, ZHAN Wen-huan. SEDIMENTARY CHARACTERISTICS OF HOLOCENE COQUINITE FROM THE HAISHAN ISLAND OF EASTERN GUANGDONG PROVINCE AND ITS PETROLOGICAL IMPLICATIONS[J]. Marine Geology & Quaternary Geology, 2006, 26(6): 45-53.
Citation: SUN Jin-long, XU Hui-long, QIU Xue-lin, SHEN Jian-wei, ZHAN Wen-huan. SEDIMENTARY CHARACTERISTICS OF HOLOCENE COQUINITE FROM THE HAISHAN ISLAND OF EASTERN GUANGDONG PROVINCE AND ITS PETROLOGICAL IMPLICATIONS[J]. Marine Geology & Quaternary Geology, 2006, 26(6): 45-53.

粤东海山岛全新世硬壳灰岩的沉积特征及其岩石学意义

SEDIMENTARY CHARACTERISTICS OF HOLOCENE COQUINITE FROM THE HAISHAN ISLAND OF EASTERN GUANGDONG PROVINCE AND ITS PETROLOGICAL IMPLICATIONS

  • 摘要: 粤东海山岛南部海积平原发育有大面积的全新世碳酸盐岩,分布范围极广,从陆上一直延伸到海域中。通过实地地质调查以及岩石薄片的镜下鉴定,发现该区发育的碳酸盐岩贝壳碎屑含量高,经大规模机械分选和搬运,大多数贝壳碎屑的粒径大于2.0 mm,胶结良好,密实,硬度大,岩层以低角度向海倾斜,倾角小于15°,根据其沉积特征和岩石学特性,本文将该处碳酸盐岩定为硬壳灰岩,而非前人所定的海滩岩或贝壳堤岩。据14C测年数据,自下而上获得典型地质剖面上3个层位的年龄分别为3 080±90、1 920±75和1 330±60 aBP,可以确定该处硬壳灰岩形成于中全新世末期至晚全新世,对应于中全新世的高海平面期。海山岛的硬壳灰岩形成于全新世冰后期海进的滨浅海环境,指示相应时期古海面潮间带至潮下带的高程。沿山麓分布的硬壳灰岩指示相应时期的潮间带,它与发育于海拔8~9 m高处的海蚀刻槽共同指示古海岸线位置。

     

    Abstract: There is an extensive area of Holocene carbonate rocks developed in the marine-deposition plain in the south of Haishan Island, eastern Guangdong Province. The carbonate rocks spread from the slope of inland hill to the sea, with a length of 3 km in E-W direction and 0.8 km in N-S direction, and the total area is almost 2.0 km2.According to our field surveys as well as sedimentary environment and petrology analyses, the carbonate rock in the Haishan Island is defined as coquinite, rather than beachrock or chenier. The coquinite is well-compacted, well-indurated, firmly cemented, and chiefly composed of fossil debris that was mechanically sorted and has experienced transport and abrasion before deposition.Most of the fossil fragments are larger than 2.0 mm in size. Three 14C samples were taken from bottom to top on a standard cross section, and their 14C ages are 3 080±90, 1 920±75 and 1 330±60 aBP respectively. The 14C data and sedimentary features indicate that the coquinite in Haishan Island was formed in mid-late Holocene (about 4~1.5 ka) in a littoral to shallow-marine environment, corresponding to the mid-Holocene high stand. The coquinite distributed around the foot of the hill indicated the location of paleo-intertidal zone. The paleo-shoreline was confirmed by the distributions of coquinite in the paleo-intertidal zone and the paleo-sea notch.

     

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