Pj. Li et al., Deep-water sediments and evolution of the Lower Triassic Xikou Formation in southwestern Fujian, China, SCI CHINA D, 41(6), 1998, pp. 639-647
The Lower Triassic Xikou Formation in southwestern Fujian, China is a set o
f complex deep-water sediments' which includes turbidites, sandy contourite
s and isolated olistoliths. Five facies and seven subfacies are recognized
in the deep-water turbidites, which are considered to belong to five facies
associations of upper, middle and lower fans, respectively. The sandy cont
ourites, which occur within turbidites as isolated thin layers with structu
res of traction current, are formed by reworking turbidites. They occur in
discrete units, not as a part of a vertical sequence of structures, such as
Bouma sequence. Paleocurrent directions derived from sandy contourites are
perpendicular to or at a large angle of those derived from turbidites. In
some areas, within the Formation there exist large oolitic limestone blocks
slided from shallow sea. The temporal-spatial distribution of three types
of sediments mentioned above and the related evidences could indicate that
a passive continental margin from shallow sea to bathyal-abyssal region, di
pping toward southeast, once occurred in study area during the early Triass
ic. The early Triassic represents a period of sealevel uprising. The uprisi
ng of sea level and the development of isolated olistoliths probably imply
gradual shrinking of an ocean basin at that time.