二叠-三叠纪之交牙形石生态新模式

通过对浙江长兴煤山剖面二叠－三叠系界线层沉积相分析及牙形石演化规律研究,提出了该时期Ｃｌａｒｋｉｎａ（Ｎｅｏｇｏｎｄｏｌｅｌａ）,Ｈｉｎｄｅｏｄｕｓ两类重要牙形石属的生态新模式．（１）Ｃｌａｒｋｉｎａ是一种底栖自由游泳生物,可出现于远岸浅海至盆地相较深水环境;（２）Ｈｉｎｄｅｏｄｕｓ是一种洋面浮游型生物,死亡之后可沉于海底的滨、浅海至深水盆地各种环境之中,并可渡过二叠－三叠纪之交海底缺氧事件这一难关,在早三叠世得到发展;因此,Ｈｉｎｄｅｏｄｕｓ可作为全球二叠－三叠系界线划分对比的可靠证据．

A NEW PALEOECOLOGICAL MODEL OF CONODONTS DURING THE PERMIAN_TRIASSIC TRANSITIONAL PERIOD

Based on detailed investigation of the sedimentology and conodont faunas on the Permian_Triassic boundary strata of the Meishan section, Zhejiang Province, South China, a new paleoecological model about two important genera Hindeodus and Clarkina (or Neogondolella ) is proposed. It suggests that Clarkina was a benthic, free_swimming genus, which often occurred in offshore to basin, deeper water, oxygen_rich environments. Hindeodus was a pelagic type found in different depth environments. Because it lived in the top layer of the water, it could survive in the anoxia bottom water during the Permian_Triassic transitional period and develop in Early Triassic. Hence, Hindeodus is a reliable criterion for subdivision and comparison of the Permian_Triassic boundary.