دانلود کتاب گیاهان و پالینومورف ها در اطراف مرز تریاس پرمین در جنوب چین

Permian-Triassic is an important stage for the earth to evolving from Paleozoic to Mesozoic. Hence, geologists in the world have been working hard on the origin, scale, content and characteristics of this specific period of development. Presently, profound achievements have been made in the study of the changes of marine biome and geologic events. The establishment of marine Permian-Triassic GSSP-global boundary stratotype sections and points in Meishan, Changxing County, Zhejiang Province, China, has marked the great progress in the research of large-scale stratatypes (Yin et al. 2001). Consequently, a great interest arose for an accurate determination and identification of an accessory GSSP in terrestrial environments. This causes induced international competition in locating a global stratotype section for such no typical section which could be acknowledged by most geologists. The previous studies on a Permian-Triassic boundary in terrestrial facies in China have been concentrated on its northern area, specially in Urumqi-Fukang-Jimusar on the southwestern margin of the Junggar Basin, where the P/T transition deposits are terrestrial. Detailed study carried out on biostratigraphy, event-stratigraphy, sedimentation and climate changes in this area facilitates this section to be competitive for a “terrestrial” GSSP of the terrestrial section. Lozovsky (1998) once suggested that the Junggar Basin in Xinjiang, China and the Moscow Basin in Russia should be the ideal candidates for the global Permian-Triassic stratotype section with their completeness and abundance in vertebrate faunas, which was interrupted by the Dalongkou event. At present, other basins, such as Karoo Basin in South Africa, Russian Terrane, Bowen Basin and Sydney Basin in Australia, are all impressive and competitive for the global stratotype. The well-conducted biostratigraphic studies on these basins have revealed the abnormal section boundary which can be correlated with that of the marine facies and thus proved the existence of various events of global significance, for instance, bacteria events, volcanism, celestial collision, and environmental collapse. Therefore, it is still necessary to find and recommend another better candidate section for the terrestrial GSSP in China.