西准噶尔乌兰柯顺地区牙形刺生物地层和沉积环境研究新进展

CONODONT BIOSTRATIGRAPHY AND SEDIMENTARY ENVIRONMENT OF THE DEVONIAN-CARBONIFEROUS STRATA IN THE WULANKESHUN REGION IN WESTERN JUNGGAR, NW CHINA

西准噶尔地区的乌兰柯顺剖面从晚泥盆世朱鲁木特组至早石炭世黑山头组地层连续,单斜出露,特别是其中跨越晚泥盆世弗拉期顶部至早石炭世杜内期底部的洪古勒楞组,宏体化石、微体化石和遗迹化石以及其他相标志丰富,岩性的三分性明显:下段为灰色—灰黄色生物碎屑灰岩;中段为紫红色—灰绿色沉凝灰岩;上段为灰绿色—灰黄色生物碎屑灰岩、钙泥质碎屑岩。该剖面是我国北方构造活动区难得的完整剖面和洪古勒楞组理想的候选层型剖面。牙形刺和其他大化石的初步研究表明,该剖面洪古勒楞组的时限为晚泥盆世末弗拉期至早石炭世早杜内期。

Devonian-Carboniferous strata in the Wulankeshun region of northwestern Junggar Basin, NW China, are represented by continuous and monoclinal outcrops of the Zhulumute, Hongguleleng to Heishantou formations. In particular, the Hongguleleng Formation contains diverse macrofossils and microfossils, as well as abundant facies indicators. Lithologically, the formation can be divided into three members. The lower member is made of gray, greyish-yellow bioclastic limestones, the middle member consists of red purple or greyish-green tuffaceous deposits, and the upper member is composed of greyish-green, greyish-yellow bio- clastic limestones and calcareous-pelitic clastic rocks. Considering that it is located in tectonically complex area, the Wulankeshun section is exceptionally preserved and should be regarded as a candidate for the type section of the Hongguleleng Formation. According to conodonts and other megafossils, the age of the Hongguleleng Formation ranges from the late Frasnian （Devonian） to early Tournaisian （Carboniferous）.