Based on the outcrop observation and thin section identification

the distribution of microbial carbonate is described and sequence stratigraphy framework is established in the Lower Cambrian Xiaoerbulak Formation in the Aksu area

Tarim Basin.Finally the carbonate platform evolution during the deposition period of the Xiaoerblak Formation is summarized and rebuilt.The results show that the Xiaoerblak Formation can be subdivided into two third-order sequences.The lower part

SQ1

corresponds to a set of microbial mats which are middle-inner ramp deposition corresponding to the stage of ramp carbonate platform.The upper part is SQ2

which is a TST

and represents a transition from ramp carbonate platform to slightly rimmed shelf carbonate platform.On the slope the tempestite deposited without microbial carbonate

while on the paleokarst highland

the large-scale transgressive mircobial reef was built through the microbial skeleton growth and correlatively bonding effect.The HST represents the stage of slightly rimmed shelf carbonate platform

where the margin and inner-platform are sharply different.On the platform margin

the EHST is characterized with chambered Epiphyton bioherm

while the LHST features some small-scale transgressive microbial bonding reefs.The inner-platform developed microbial shoal facies during the high stand

and its EHST is absent.The inner-platform LHST is characterized by laminites

spongiostromata stromatolites and stromatolites.Their formation is related to the sticky microbial mats.