广西玉林早泥盆世早期腕足动物生物地层研究

A Biostratigraphical Study of the Early Early DevonianBrachiopods from Yulin, Guangxi

在广西玉林樟木地区早泥盆世北均塘组、良合塘组、樟木组３５属４８种腕足动物演化和地层分布特征研究的基础上，建立了６个腕足动物生物带（自下而上）：１．Ｑｕａｄｒｉｔｈｙｒｉｎａｅｘｐａｎｓａ－Ｐｒｏｄａｖｉｄｓｏｎｉａｍｉｒａｂｉｌｉｓ带；２．Ｇｒａｙｉｎａｍａｇｎｉｆｉｃａｇｕａｎｇｘｉｅｓｉｓ－Ｓｃｈｉｚｏｐｈｏｒｉａｓｕｌｃａｔｉｎａ带；３．Ｒｅｔｉｃｕｌａｒｉｏｐｓｉｓｃｏｓｔａｔｕｓ带；４．Ｇｒａｙｉｎａｍａｇｎｉｆｉｃａｓｉｎｉｃａ带；５．Ｑｕａｄｒｉｔｈｙｒｉｓｒｏｂｕｓｔａ－Ｂｏｕｃｏｔｉａ带；６．Ｑｒｉｅｎｔｏｓｐｉｒｉｆｅｒｗａｎｇｉ带。依据国际对比和与笔石的层位关系认为：第１－３带为晚洛赫柯夫期，并且１、２、３带很可能分别相当晚洛赫柯夫早、中、晚期；第４带为早布拉格早期；第５、６带分别相当中、晚布拉格期。

Based on the evolution of brachiopod communities and ranges of the brachiopod fauna of the Late Lohkovian-Pragian age from the Yulin region, Guangxi, 6 biozones are recognized (in ascending order):1) Quadrithyrina expansaProdavidsonia mirabilis Zone; 2) Grayina magnifica guangxiensisSchizophoria sulcatina Zone; 3) Reticulariopsis costatus Zone; 4) Grayina magnifica sinica Zone; 5) Quadrithyris robustaBoucotia Zone; 6) Orientospinifer wangi Zone. Zones 1-3 are considered to be Late Lochkovian in age, Zone 4 early Early Pragian, Zone 5 Middle Pragian and Zone 6 Late Pragian on the basis of international correlations of the brachiopods and the stratigraphical relationship between brachiopods and graptolites.