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摘要:1 Introduction During the Cretaceous the northern margin of the Indian Plate was part of a continental slope and shelf that faced northwards towards an ocean now subducted along the line of the Yarlung Zangbo Suture. Southern Tibet was a part of this TethysHimalayan Sea in which a variety of gravity-flow sandy strata and pelagic sediments accumulated along with volcanic and siliciclastic deposits(Wan et al., 2005). The most complete marine Cretaceous-Paleogene deposits in China are preserved in southern Tibet, which well records the evolution of the Neo-Tethyan Ocean and the collision characteristics of the Eurasian and Indian plates(Willems and Zhang, 1993; Wan et al., 2005; Li et al., 2005, 2007, 2009, 2011 a). This study concerns the planktic biostratigraphy of Late Cretaceous in the Gongza, Tingri, southern Tibet. 2 Materials and methods The Gongza section is located in ~15 km west to the Tingri town, southern Tibet, which was defined as deposited on the Greater Indian passive continental margin. The Gambacunkou Formation and the Zongshan Formation of this section are respectively mainly composed of micofossil-bearing shale(bedded with some limestone) and limestone, which represented the southern Tethyan passive margin succession. 68 samples were taken for study on the planktonic foraminiferal biostratigraphy of upper Gambacunkou Fm and lower Zongshan Fm in the Gongza section. The extraction and identification of the planktonic foraminiferas were carried out in the Micropalaeontology Laboratory of the China University of Geosciences(Beijing). To free the foraminferal fossils from the rocks(mainly shale), the following procedures were followed: samples were broken into the pieces with the particle size of 0.6-1 cm and placed in beakers. A diluted(10~15%) anhydrous sodium sulfate solution was added to cover the rocks for about two weeks. The samples were wet sieved using 20 and 250 mesh sieves and the residual samples were dried and examined. Representatives of each species were measured, gold-coated and imaged using a Scanning Electron Microscope(SEM).3 Planktic foraminiferal biostratigraphy The detailed study has been carried out on the planktonic foraminiferal biostratigraphy of the upper Gambacunkou Formation and lower Zongshan Formation in the Gongza section and 22 species of 8 foraminferal genera were identified, the important elements(Fig.1) of which include Dicarinella concavata, D. imbriticata, D. asymetrica, Globotruncana linneiana, G. lapparenti, G. arca, G. ventricosa, G. falsostuarti, Globotruncanita elevata, G. stuartiformis, G. stuarti, Heterohelix cordites, and Radotruncana calcarata etc. Four planktonic foraminiferal biozones were recognized as follows(in ascending order): 3.1 Dicarinella asymetrica zone The important elements of this zone are D. asymetrica, D. concavata, D. imbriticata, G. linneiana, G. lapparenti, and G. arca etc. The age of this zone belongs to Santonian of Late Cretaceous. 3.2 Globotruncanita elevata zone T
会议名称:

第九届世界华人地质科学研讨会

会议时间:

2019-06-01

会议地点:

中国吉林长春

  • 专辑:

    基础科学

  • 专题:

    生物学; 地质学; 地质学

  • DOI:

    10.26914/c.cnkihy.2019.028428

  • 分类号:

    P534.53;Q915

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