The lower Trassic developed on the north-west slope of Shiwandashan basin in Guangxi is represented predominently by marine carbonate sediments

which can be subdivided into two opposite lithofacies zones according to their sedimentaty attributes. The north facies zone

occurred at carbonate platform

is featured by oolitic limestone

894-970m thick;while the southern one

developed in a basin environment

is represented by lamellar limestones

warty limestones and shales

as well as psephitic and calcarenites

the thickness of which varies from 307-521m. The lamellar limestones

warty limestones and the shales are autochthonous rocks

whereas psephitic and calcarenites are allochthonous sediments

i.e. carbonates of gravity flow origin. Gravity flow in present region can be divided into three types

notably debris

turbidity and grain. Of them

the most important one is debris flow which have givrn rise to more than a hundred meters of sediments. varying from bedded to massive coarse calcirudites and occupying 80-90% of the total thickness.Turbidity flow is composed of fine calcirudites and calcarenitos with positive gradation. This type of rocks is widely distributied and characterized by minor thickness for each individual bedding. Grain flow consists of medium calcirudites to calcarenites

with a rather unighe texture. On probability diagram showing gradation

all kinds of gravity flow sediments exhibit gentle and smooth curves covering a wide size range of particles

but each type of sediments have its own attributes. They are clearly different in their size range parameters and have distinction both on CM and scatering diaagrams. Gravity flow sediments were derived mainly from the simultaneous carbonate platform sediments(extraclasts)

and also from micrites consolidated to some extent in the basin (intraclasts). A steeper slope primarily existed between the platform and the basin

the depth of which at the end of Trassic might be 800-1000m. The study on carbonate gravity flow not only can make direct contribution to dealing with sedimentary environment and compilation of lithofacies-paleoge-ographical map

but also give important guidance to petroleum prospecting and exploration.