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湘西黔东下、中寒武统沉积环境 被引量:7
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作者 梁仁枝 李汉瑜 +1 位作者 刘宝珺 许效松 《沉积学报》 CAS CSCD 北大核心 1991年第2期16-24,共9页
本文论述了对湘西黔东地区早、中寒武世的碳酸盐岩和陆源碎屑沉积的分析研究结果,着重探讨了控制该区陆表海沉积层序的各种动力因素。在研究区内,4种垂向层序均具有向上变浅的旋回性。早寒武世晚期的藻丘缓斜坡与中寒武世的鲕粒陡斜坡... 本文论述了对湘西黔东地区早、中寒武世的碳酸盐岩和陆源碎屑沉积的分析研究结果,着重探讨了控制该区陆表海沉积层序的各种动力因素。在研究区内,4种垂向层序均具有向上变浅的旋回性。早寒武世晚期的藻丘缓斜坡与中寒武世的鲕粒陡斜坡上的沉积动力学特征为:滨岸正常波浪潮汐流,滨岸及内陆棚的风暴营力,垂直于古岸线的大规模地滑和重力流,沿古岸线及斜坡的等深流。沉积小旋回的成因系构造断块的脉动,而盆地边缘的海退序列则由板块相对扩张、海平面变动及碳酸盐岩自身成长所控制。 展开更多
关键词 沉积环境 早寒武统 武统 盆地
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New observations on Vetulicola longbaoshanensis from the Lower Cambrian Guanshan Biota(Series 2, Stage 4), South China 被引量:2
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作者 LI JinShu LIU JianNi OU Qiang 《Science China Earth Sciences》 SCIE EI CAS CSCD 2017年第10期1795-1804,共10页
Cambrian vetulicolians are enigmatic metazoans which play an important role in understanding the early animal evolution. Vetulicola longbaoshanensis Yang et al., 2010 is a unique species reported from the Guanshan Bio... Cambrian vetulicolians are enigmatic metazoans which play an important role in understanding the early animal evolution. Vetulicola longbaoshanensis Yang et al., 2010 is a unique species reported from the Guanshan Biota, Cambrian Series2, Stage 4 at eastern Yunnan, South China, which expands our understanding of vetulicolians. Here, new exceptionally preserved materials of V. longbaoshanensis from the Lower Cambrian Wulongqing Formation(which yields the so-called Guanshan Biota)in both Wuding and Kunming areas are described, in which the gill structures of V. longbaoshanensis are well preserved. The gill structures of our fossils are more complicated than those in the type species: the gill sac is gourd-shaped and can be divided into a smaller anterior part and a larger posterior part, prominent gill silt and dense gill filaments present in the joint of the two parts. Comparative analyses indicate that vetulicolians from the Guanshan Biota are similar to the Vetulicola rectangulata Luo et Hu, 1999 from the Chengjiang Biota in gross morphology. However, compared with the V. rectangulata, the Guanshan forms possess a larger body size, a higher length/height ratio of anterior body, and a higher ratio of gill sac width to anterior body height, probably typifying the derive characters anticipated of vetulicolians. These new materials, therefore, shed new light on our understanding of vetulicolians morphology and the early evolution of the gill structures. 展开更多
关键词 Vetulicola longbaoshanensis Guanshan Biota Chengjiang Biota Lower Cambrian
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