Dahalajunshan Fm

The type section is located at Dahalajun Mt. southeast of Tekes County, Xinjiang. It was named by Tan Hongbing et al. in 1976, and formally cited in Regional Stratigraphical Scale of Xinjiang in 1981.

Volcanics and Sandstone. The formation at the lower reaches of the Kekesu River is dominated by purple-red, gray-purple and gray-green andesites, andesitic porphyrite, amygdaloidal pyroxene-andesitic porphyrite, andesitic agglomerate and andesitic tuffaceous lava. There is a conglomerate layer on the bottom, going up from which are intercalated intermittently tuffaceous sandstone, tuffaceous conglomerate, fine-grained sandstone, conglomerate, sandy limestone and dolomitized limestone, with an exposed thickness of 1041 m. The lithology changes greatly, locally with clastic rocks or lava increasing. The thickness reaches 3771.2 m at maximum, and generally 1000−2000 m.

In the Kuerdaihe section of Tekes County, the organic limestones contain Coral Syringopora sp. The Asaigensayi section yields Corals Siphonophyllum sp., Lithostrotion sp., Diphyphyllum sp., Palaeosmilia sp., and Dibunophyllum sp., Brachiopods Gigantoproductus sp., Semiplanus sp., and Dictyoclostus sp.; Fusulinid Eostaffella sp., etc. Brachiopod Echinoconchus elegans and Coral Lithostrotion sp., etc. have also been collected at Tulasunan of Yining County.

It is interpreted as shelf-neritic clastic rocks and volcanic eruptive rocks, locally intercalated with carbonate rocks