黔北含祁阳蚌地层及其时代讨论
A DISCUSSION OF THE STRATA CONTAINING THE QIYANGIA FAUNA IN NORTHERN GUIZHOU AND THEIR AGE
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摘要: 近年来,我国南方在许多地区中生代地层中发现有属珠蚌科内一个淡水至半咸水相新属——祁阳蚌(Qiyangia)。由于该属特征明显,产出层位稳定,分布广泛,已被大多数地层古生物工作者视为华南地区早侏罗世地层划分、对比的一个重要瓣鳃类化石。新近,笔者在黔北地区进行1∶20万区调工作时,发现祁阳蚌不仅出现在产有禄丰蜥龙动物群的自流井群下部,而且大量分布在“香溪群”上部地层中,并有湖南“观音滩生物群”中的其Abstract: The Regional Geological Survey Brigade of Guizhou Province found the Qiyangia fauna—a characteristic Early Jurassic pelecypod fauna of South China—a few years ago when the brigade conducted regional survey work on a scale of 1:20000 in the western part of northern Guizhou. The Qiyangia fauna not only occurs in the lower part of the Ziliujing Group containing the Lufengosaurus fauna but also is found in great abundance in the upper part of the"Xiangxi Group", and is associated with fish fossils resembling the "Yumushan fish group" of Hunan. The pelecypods Qiyangia, Hunanella and Apseudocardinia of the fauna are different from the Late Triassic Indosinion-Permophorus assemblage in the lower part of the"Xiangxi Group"and the Middle Jurassic Lamprotula (Eol.)-Pseudocardinia assemblage in the upper part of the Ziliujing Group. In the light of that, the author suggests that the age of the strata containing the Qiyangia fauna be assigned to Early Jurassic and correlated with the Guanyintan Formation of southwestern Hunan, the Xiangxi Formation of western Hubei and the Lower Lufeng Formation of eastern Yunnan, respectively.