Sanjianfang Fm
Type Locality and Naming
It was named by Xia Gongjun as the Sanjianfang System in 1956. The naming locality is situated at Sanjianfang west of Hami City, Xinjiang (Xia Gongjun, 1956, Report on the Summary of the Compiler
Jingeng Sha (coordinator) Researches in the Tulufan Basin, unpublished). In 1981 the Compiler
Jingeng Sha (coordinator) Group for the Regional Stratigraphic Chart of Xinjiang recommended that the Lianmuxin section of Shanshan County, Xinjiang be taken as the reference section for the particular formation.
Synonym: （三间房组）
Lithology and Thickness
It represents brown-red and grey-green sandy mudstones, intercalated with thin-, and medium-bedded sandstones and conglomerates, with a thickness commonly of 38-387 m, except for the Lianmuxin area where it is 164 m thick.
Relationships and Distribution
Lower contact
It is in a conformable contact with the underlying Xishanyao Fm. Schematic strat column shows Kezilenur Fm (upper Kelasu Gr) as the next older unit.
Upper contact
It is in a conformable contact with the overlying Qiketai Fm
Regional extent
The particular formation is distributed mainly in the Tulufan-Hami Basin. In the areas of the Huoyan Mts, Qiketai of Shasha County and Sanjianfang the particular formation can be definitely divided, but on the margins of the basin, for instance in the areas of Kekeya, Ortang, Qichang Lake, Meiyao Gully in the northern part of the basin, and in the Takequan area and the area to the south of the Liaodun region, Hami City in the southern part of the basin, the particular formation is hard to be differentiated from the overlying Qiketai Formation.
GeoJSON
Fossils
It yields bivalve fossils such as Pseudocardinia yumenensis and P. carinata; plant fossils as represented by Coniopteris hymenophylloides, as well as spore-pollen fossils.
Age
Depositional setting
Additional Information
It yields bivalve fossils such as Pseudocardinia yumenensis and P. carinata; plant fossils as represented by Coniopteris hymenophylloides, as well as spore-pollen fossils.
Age:
Schematic stratigraphic column had suggested Early Bajocian. However, comparison to Junggar Basin (being below revised age for Qiketai Fm) suggests equivalnce with Xishanyao Fm, and Diying Huang (2019; Jurassic integrative stratigraphy and timescale of China. Science China: Earth Sciences, v. 62) re-assigns this Xishanyao Fm as Bathonian through mid-Oxfordian.
Age span:
Beginning stage: Bathonian
Fraction up in beginning stage: 0.0
Beginning date (Ma):
Ending stage: Oxfordian
Fraction up in ending stage: 0.5
Ending date (Ma):
Depositional setting:
Depositional-pattern:
Additional Information
Compiler
Jingeng Sha (coordinator)