Douzui Fm

The type section is located near Douzui Village of Gumu Town, 10 km south of the Wenshan County (104^o15’E-23 ^o16’). It was named by Chen Xiaolin and Wang Chenxing in 2002 as a sedimentary wedge (lithesome) - an informal lithostratigraphic unit.

Limestone redeposited beds. Lower part, more than 100 m thick, is composed of thin- to medium-bedded micritic limestone bearing-tentaculites and bioclastic peloidal limestone, 5-30 cm thick for each single bed with horizontal laminations. Upper part, 260 m thick, exhibits more than twenty sedimentary cycles, which consist of thin-bedded limestone with sliding structures, breccia limestone and turbidite limestones. The breccia is poorly sorted, usually tabular and subangular shape, ranging from several millimeters to tens centimeters in size. It consists dominantly of dolomites, bioclastic limestones plus thin-bedded cherty limestone, with stylolite or truncated lower contact. The turbidite deposits are composed of alternating thin- to medium-bedded micrite, bioclastic peloidal limestone and bioclastic or detrital limestone with horizontal, wavy and graded beddings constituting incomplete Bouma sequences.

Figure Photographs showing the thin-bedded limestone with horizontal laminations of the lower part of Douzui Fm (upper image) and the breccia limestone of the gravity current deposits (lower image). Length of pencil 14 cm. (after Chen and Wang, 2002).

It is reported that the lower part contains Conodonts from Polygnathus dehiscens to Pol. serotinus Zones and Tentaculite fossils from Nowakia praesursor to N. cancellata Zones. But no descriptions and figures are given.

It is interpreted as a platform margin and upper slope facies including gravity and nongravity current deposits.

According to the lithology, fossil contents and stratigraphic position, the so-called lithesome would be correlated with Daliantang Fm.