Shishugou Gr
Type Locality and Naming
It was named by Fan Chenglong in 1957. The naming section is located at Shishu Gully of Jimusar County, Xinjiang (Fan Chenglong and others, A Summary Report on the Geological Work Conducted by the Comprehensive Geological Research Party in the Junggar in 1957, unpublished). Approximate coordinates: 44.5°N 90.2°E.
Synonym: （石树沟群）, Shishugou Fm, Shuixigou Gr. The Wucaiwan Mbr, the lowest unit of the Shishugou Fm, was once considered as a separate underlying formation.
Lithology and Thickness
It represents green, grey-yellow and red sandy mudstone and mudstone layers, intercalated in its lower part with sandstone and conglomerate. " At the Wuwaican locality, the formation is approximately 380 m thick, the lower 30 meters of the formation predominantly consist of conglomerate, with the majority of the formation consisting of red colored mudstone with frequent channel/sheet sandstone lenses and occasional tuffaceous deposits."
"The Shishugou Fm dinosaur traps also known as death pits or death traps are pit structures found within the formation that are noted for their fossil content. These 'traps' or 'bonebeds' are unusual in that they consist of vertically stacked skeletons of numerous non-avian theropods in 1–2 m deep pits. The pits are filled with a mix of alluvial and volcanic mudstone and sandstone and appear to have been created by the trampling and wallowing of large dinosaurs. Small theropods and vertebrates then became mired in these pits, dying and being forced deeper by the activities of the large dinosaurs and the struggles of later victims. The high quality of preservation suggests a rapid burying of the carcasses. … On analysis of the rock matrix, large amounts of volcanic ash were found, hinting at eruptions during that period, the ash raining onto the marsh creating viscous mud and becoming subsequent death traps. To date three of these death pits have been located. " [See Additional Information" below]
Relationships and Distribution
Lower contact
Regionally, the next older unit is indicated as or indicated to overly the Xishanyao Fm (Wikipedia entry; See Additional Information]
Upper contact
It was commonly overlain disconformably by the Tugulu Gr. However, other sources indicate it is overlain by the Kalaza Fm (See Additional Information entry).
Regional extent
The Shishugou Gr is distributed on the eastern margin of the Junggar Basin, and in the region of Kalameli-Jiangjun Gobi-southwestern margin of the Santanghu Basin, with a thickness commonly of 50-700 m, and with a slight variation in its lithology which lies in its being composed of yellow sandstone, mudstone and conglomerate, intercalated occasionally with carbonaceous shale, containing silicified woods; westerly till the Beita Mts the grains of the rocks are getting finer, with a thickness being of 506-1443 m. In the areas of the Hongshan Coal Mine, the Jiangjun Temple and the Shishu Gully-Shaqiu River region the particular group represents variegated banded strata; while in the areas of Fuyun, the lower reaches of the Qinggeli River and the northern foothill of the Kelameili Mts it represents alternating layers of variegated sandstones.
It is laterally equivalent to the Qigu Fm (Tithonian) in the southern half of Junggar Basin.
GeoJSON
Fossils
"The Shishugou Formation is considered one of the most phylogenetically and trophically diverse Middle to Late Jurassic theropod fauna." (see Additional Information below). It contains a great amount of silicified woods, which serves as one of the characteristics of the particular group. It also yields Reptilia fossils as represented by Tianshansaurus chitaiensis in the area of Shishu Gully and on the western side of the Lasitie region, as well as by Branchiosauridae and Megalosauridae in the Sangequan-Jiangjun Temple region; Ostracoda such as Darwinula impudica and D. sarytirmenensis; plant fossils such as Coniopteris hymenophylloides, Equisetites sp., Elatocladus sp. and Cupressionxylon sp.; as well as spore-pollen fossils such as Hymenophyllum sp., Osmunda sp., Pinnus sp., Psophospaera sp. and Conifera sp. (Shishu Gully).
Age
Depositional setting
"At the time the area was covered by marshland, adjoined a small mountain range peppered with volcanoes, and was inhabited by dinosaurs, small crocodilians and amphibians. Currently it is a sparsely settled region of dry washes, arid badlands and dunes along the Gobi desert’s western edge. The Shishugou Fm consists of mudstone, siltstone, and sandstone, and is named for the silicified wood or petrified logs found here. ('Shishugou' = 'stone tree valley') These badlands were used for some sequences in the film Crouching Tiger, Hidden Dragon, the genus Yinlong ('hidden dragon') being named for the film." [See Additional Information.]
Additional Information
Lithology-pattern: Sandy claystone
Relationships and Distribution:
Lower contact:
Regionally, the next older unit is indicated as or indicated to overly the Xishanyao Fm (Wikipedia entry; See Additional Information]
Upper contact:
It was commonly overlain disconformably by the Tugulu Gr. However, other sources indicate it is overlain by the Kalaza Fm (See Additional Information entry).
Regional extent:
The Shishugou Gr is distributed on the eastern margin of the Junggar Basin, and in the region of Kalameli-Jiangjun Gobi-southwestern margin of the Santanghu Basin, with a thickness commonly of 50-700 m, and with a slight variation in its lithology which lies in its being composed of yellow sandstone, mudstone and conglomerate, intercalated occasionally with carbonaceous shale, containing silicified woods; westerly till the Beita Mts the grains of the rocks are getting finer, with a thickness being of 506-1443 m. In the areas of the Hongshan Coal Mine, the Jiangjun Temple and the Shishu Gully-Shaqiu River region the particular group represents variegated banded strata; while in the areas of Fuyun, the lower reaches of the Qinggeli River and the northern foothill of the Kelameili Mts it represents alternating layers of variegated sandstones.
It is laterally equivalent to the Qigu Fm (Tithonian) in the southern half of Junggar Basin.
GeoJSON:
Fossils:
"The Shishugou Formation is considered one of the most phylogenetically and trophically diverse Middle to Late Jurassic theropod fauna." (see Additional Information below). It contains a great amount of silicified woods, which serves as one of the characteristics of the particular group. It also yields Reptilia fossils as represented by Tianshansaurus chitaiensis in the area of Shishu Gully and on the western side of the Lasitie region, as well as by Branchiosauridae and Megalosauridae in the Sangequan-Jiangjun Temple region; Ostracoda such as Darwinula impudica and D. sarytirmenensis; plant fossils such as Coniopteris hymenophylloides, Equisetites sp., Elatocladus sp. and Cupressionxylon sp.; as well as spore-pollen fossils such as Hymenophyllum sp., Osmunda sp., Pinnus sp., Psophospaera sp. and Conifera sp. (Shishu Gully).
Age:
"Excavations since 2000 have revealed a wealth of fossils dating from a period some 165 to 155 million years ago." (unfortunately, logic of geologic stage not indicated). For graphic purposes, the bounding of the Shishugou Gr between the Qigu Fm and Toutunhe Fm implies mid-Oxfordian through Tithonian based on those other formationa age assignments by Diying Huang (2019; Jurassic integrative stratigraphy and timescale of China. Science China: Earth Sciences, v. 62).
Age span:
Beginning stage: Oxfordian
Fraction up in beginning stage: 0.5
Beginning date (Ma):
Ending stage: Tithonian
Fraction up in ending stage: 1.0
Ending date (Ma):
Depositional setting:
"At the time the area was covered by marshland, adjoined a small mountain range peppered with volcanoes, and was inhabited by dinosaurs, small crocodilians and amphibians. Currently it is a sparsely settled region of dry washes, arid badlands and dunes along the Gobi desert’s western edge. The Shishugou Fm consists of mudstone, siltstone, and sandstone, and is named for the silicified wood or petrified logs found here. ('Shishugou' = 'stone tree valley') These badlands were used for some sequences in the film Crouching Tiger, Hidden Dragon, the genus Yinlong ('hidden dragon') being named for the film." [See Additional Information.]
Depositional-pattern:
Additional Information
Extensive entry in Wikipedia on the famous dinosaur assemblages (https://en.wikipedia.org/wiki/Shishugou_Formation)