Lieyi Fm
Type Locality and Naming
The type section is located at Dangen-Dedagou, Batang County, Sichuan. It was named by the third District Geological Survey Group of Sichuan Geological Bureau in 1966. It was firstly used in publication by the first District Geological Survey Group of Sichuan Geological Bureau in 1977. The lithology of the Middle Triassic in Yidun and Daocheng is complex, and all of them belong to the Lieyi Fm, which obviously violates the naming principle of lithostratigraphic units. Due to the poor current researches, it was temporarily collectively referred to as the Liyi Fm.
Synonym:
Lithology and Thickness
It is dominated by gray medium-thick layer metamorphic sandstone, sandwiched between slate and phyllite. There are many sandstones in the lower part, slate and phyllite in the upper part, and unstable almond-shaped basalt, diabase porphyry and limestone lenses are seen near the top. The total thickness is about 2185 m.
Relationships and Distribution
Lower contact
The metamorphic conglomerate at the bottom is in conformable contact with the phyllite at the top of the underlying Dangen Fm
Upper contact
Overlain by the Qugasi Fm, or by the Genlong Fm (similar age as Qugasi Fm), depending on location.
Regional extent
It is distributed in Baiyugongna, Niru and Heihaizi of Zhongdian and Zhongyi of Lijiang. The lithology and thickness of this group vary greatly. In Baiyugongna, there are two sets of gray-green altered andesite and altered andesite porphyry in the sand slate in the lower part; in the middle and upper parts are composed of sandstone, slate and limestone with a total thickness of 1330 m. In Zhongdianniru, Heihaizi and Zhongyi of Lijiang, it is divided into upper and lower parts according to lithology: the lower part is gray-green, purple-red, gray massive basalt, almond-shaped basalt, and volcanic breccia Flysch composed of rock, tuff and sand slate, with a maximum thickness of 3595 m.
GeoJSON
Fossils
In Heihaizi area, in the lower part of this formation, bivalves: Costatoria goldfussi mansuyi. In Zhongyi, in the upper part of this formation, ammonoids: Balatonites? sp.; bivalves: Bakevellia costata, Plagiostoma cf. bourret, Leptochondria subparadoxica, Neoschizodus laevigata.
Age
Depositional setting
Marine volcano-sedimentary sequence.
Additional Information