南盘江地区晚二迭世沉积相及火山碎屑岩成因

南盘江地区地跨滇、黔、桂三省，是西南地区油气勘探瞩目的地区之一。地史上从晚二迭世到三迭纪都是强烈的沉陷区，周围被古、中生代发育的一些古隆起(或古陆)包围，面积约二十万平方公里。本文着重对晚二迭世沉积相和火山碎屑岩成因迸行研讨，重点放在南盘江断榴盆地区。

RESEARCH INTO THE SEDIMENTARY FACIES AND THE ORIGIN OF VOLCANICLASTIC ROCKS OF LATE PERMIAN AGE IN THE NANPAN RIVER AREA

In this paper we mainly discuss the sedimentary facies and volcani clastic turbidites of the trough-fault basin which makes up the southern and central parts of the Nanpan River Area. This area is about 200,000 km2 and located in the junction of Yunnan, Guazhou and Guangsi provinces.During Dong Wu movement, as a result of the rifts in NW. NE and SN directions in this area, paleostructure was formed from the graben type trenches alternating with the isolated platfoms. There is quite thick spilite erupted in the west and intrusion of comagmatic diabase in the east. Later on, there frequently happened intermediate magma eruption. On the basis of the results of the field and laboratory work we have proved that the latter—the intermediate rock is a kind of andesitic volcaniclastic turbidite that erupted along the rift belt on sea flour and belongs to a volcanic ash flow type. We have presented the pattern of the sedimentary facies of this area—five sedimentary regions and eight facies belts.In addition, we have pointed out that in oil and gas exploration the attention should be focused on the reef belts around the platform margins which are covered with volcaniclastic turbidite after retreating, and on the upper fan and channels of apron facies where volcaniclastic turbidite and the turbidite fan of calcarenite overlap.