Harjiawu Fm
Type Locality and Naming
The type section is located in the east of the Harjiawu area to the southeast of Jimunai County Town, Xinjiang. It was named by the 3rd Regional Geological Survey Expedition under the Geological Bureau of Xinjiang in 1959.
Lithology and Thickness
Volcaniclastics. Its Lower part is composed of grey-green tuffaceous conglomerate, tuff, tuffaceous sandstone and volcanic breccia. Its basal part is composed of grey-black siltstone. Its Upper part is composed of grey-green andesitic porphyrite with vesicular structure, massive intermediate tuff, volcanic breccia, felsophyric volcanic breccia, felsophyric breccia-rhyolite and andesitic tuff. Thickness is 1115 m
Relationships and Distribution
Lower contact
Unconformable (effusive) contact with the underlying Salbulak Fm of the upper Carboniferous Series (maybe it is uppermost unit of the Kalaerqisi Gr?)
Upper contact
Conformable contact with the overlying Kalagang Fm
Regional extent
Distributed in the West Jungghariya area. Northwesterly from Harjawu till the surrounding area of the Jimunai County the contact of the formation with the underlying strata is uncertain, with a greatly changeable lithology, where its lower part is composed of andesitic porphyrite, basaltic porphyrite and tuff; from west to east the volcanic rocks are gradually changeable from intermediate and intermediate-acidic into intermediate and intermediate-basic ones, meanwhile the volcaniclastic rocks are reducing in amount, and the lavas are increasing in amount, with a thickness of 1112-2489 m.
GeoJSON
Fossils
Plant fossils (phytolites) of Angaropteridium-Zamiopteris assemblage.
Age
Depositional setting
It is interpreted as continental volcanics deposits.
Additional Information