The Luohe Formation an

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

Geologic

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

. It is located in the

Ordos Basin The Ordos Plateau, also known as the Ordos Basin or simply the Ordos, is a highland sedimentary basin in parts of most Northern China with an elevation of , and consisting mostly of land enclosed by the Ordos Loop, a large northerly rectangular ...

, and records dinosaur fossil trackways.

Geology

The formation mainly consists of three lithologic members: the lower member is a dark purple-red and purple-gray massive mudstone with dark purple micro-thin bedded

argillaceous Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay mineral ...

siltstone, and grey-yellow thick-bedded conglomeratic sandstone with horizontal bedding and low-angle oblique bedding developed. The middle member consists of purple-red thin-bedded quartz-fine sandstone and fine-medium grained

feldspathic Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagiocla ...

quartz sandstone, generally with large tabular oblique bedding, cross-bedding and parallel bedding. The upper member consists of purple-red and grey-yellow massive mudstone, silty mudstone and thin-bedded argillaceous siltstone, with parallel bedding and low-angle oblique bedding developed.

Depositional environment

The Luohe Formation represents an aeolian

dune field A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...

with interspersed interdraa deposits. Sandstone wedges were identified at three different outcrops, representing infilling of thermal contraction cracks. This

periglacial Periglaciation (adjective: "periglacial", referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing and freezing, very often in areas of permafrost. The meltwater may refreeze in ice wedg ...

scenario is analogous to that of the Qiongkuai Lebashi Lake area,

Xinjiang Uygur Autonomous Region Xinjiang,; , SASM/GNC: previously romanized as Sinkiang, officially the Xinjiang Uygur Autonomous Region (XUAR), is an autonomous region of the People's Republic of China (PRC), located in the northwest of the country at the crossroads ...

. This Cretaceous plateau desert was estimated to be around 3-4km paleoaltitude at a subtropical latitude.

Fossils

Likely Deinonychosaurian and other small indeterminate

Theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

trackways have been identified in the Luohe Formation.

References

{{reflist Geology of China