滇西南昌宁-孟连带南皮河群地层、沉积特征及其构造古地理意义

STRATIGRAPHY,SEDIMENTOLOGY AND TECTONIC PALAEOGEOGRAPHY OF THE NANPIHE GROUP IN THE CHANGNING-MENGLIAN ZONE,SOUTHWESTERN YUNNAN

关键词:  南皮河群  沉积特征  构造古地理

Key words:  southwestern Yunnan  Nanpihe Group  sedimentary characteristics  tectonic palaeogeography

摘要:

南皮河群位于滇西南昌宁-孟连带西区,其地层序列已受到后期构造作用改造,总体呈无序状态,但其内部的各岩片地层仍保持相对连续的地层层序。据此,我们将南皮河群划分为下、中、上段,对其中各段的沉积特征和构造背景作了详细研究。南皮河群下段为一套浊流、滑塌浊流、碎屑流和等深流沉积类型;中、上段为深水洋盆边缘沉积类型,其沉积构造背景为被动大陆边缘呈拉张状态的深水陆坡-洋盆边缘环境,物源区为西侧的保山-耿马地块。

Abstract:

The Nanpihe Group is located in the western part of the Changning-Menglian zone in southwestern Yunnan.Although its stratigraphic successions have been reworked chaoti-cally by tectonism,there exist a lot of stratal slices with relatively continuous sequences. The sedimentary characteristics and tectonic settings enable the distinction of three mem-bers:upper,middle and lower members.The lower member of the Nanpihe Group is made up of a series of turbidites,fluxoturbidites,debris flow deposits and contourites.The middle and upper members of the group consist of the deposits on the margins of the deep-water oceanic basin.The tectonic settings of the group represent the deep-water exten-sional continental slope to oceanic basin margin environments on the passive continental margin.The principal source of detritus lay to the western Baoshan-Gengma block.