Rigainpunco Gr
Type Locality and Naming
"Tibet area in 1986 in 1:1 million "change the picture control" report, the Qiangtang region (north, qiang qiang south) of the Triassic strata are called "xiao tea" group, on behalf of the late Triassic sedimentary in the area, in 1989, found in writing the Tibet geology of south and qiang qiang north of Triassic strata in Long Mu wrong - check mulberry - Lancang river fracture is bounded on both sides of a significant difference." [English-translation text as provided by the lexicon compilers.] In 1993, the Geology of Tibet retained the Xiaochaka Gr in the northern Qiang region, and changed the original Xiaochaka Gr in the southern Qiang region into the Rigainpunco Gr. In 1997, the "Tibetan Rock and Stratigraphy" followed this treatment opinion. The named section is located in Rigan Matco, east of Senduo, Gaize County, Tibet.
Synonym:
Lithology and Thickness
Sedimentary cycles of gray thick to middle calcareous siltstone, calcareous slate, calcareous fine sandstone and gray thin-bedded limestone, silty limestone, banded limestone, clastic limestone, and pebbled limestone.
Relationships and Distribution
Lower contact
The bottom boundary is marked by sandstone with horizontal bedding, wavy bedding, and hieroglyphic impression, without an observed lower limit and is usually fault-missing. The original contact relationship to the underlying Oula Fm (Oula Gr) has not been reported so far.
Upper contact
Regionally, the next younger unit is the Jipucun Fm of Rhaetian (latest Triassic).
Regional extent
The deposition thickness varies greatly. In the western section, the thickness is about 1100 m in Domaghipuriya area of Ritu County. In the middle section, near Gaize, the thickness of the stratum is about 10,800 m at most. The eastern section, in the Shuanghu Siwa area and reduced to about 500 m. Another characteristic is that the closer to the Bangongcuo - Nujiang fault zone, the thicker the strata are. The thickness decreases away from the fault zone. In other words, the thickness near the fault can reach 10,000 meters, but to the north away from the fault zone to Beilicuo area, the thickness of about 3000 meters. In the vicinity of Duoxiongnan and Normaco, the lower part is composed of limestone and thick bedded limestone, the middle part is composed of limestone and siltstone with biological lime-dust, and the upper part is composed of gray-black mudstone with yellowish-brown shell limestone, with a total thickness of more than 4450 m.
GeoJSON
Fossils
It contains bivalve fossils Pseudolimea cf. Planoplicata, Entolium tenuistriatum rotumdum, Pleuromya cf. Musculoides, Phaenodesmia cf. klipsteiniana, Palaeocardita langnongensis, Tulongocardium cf. nequam, Cattilla cf. nyanangensis, Cassianella cf. equistriata, astroies Thecosmilia, Thamnasteria, Montlivaltia, brachiopod fossils Zeilleria cf. Mosseievi, Aulacothyropsis pentagonalis, Timorhynchia sulcata, Laballa suessi, Koninckina cf. Elegantula, Pseudorugitela pulchella and gastropods.
Age
Depositional setting
It is interpreted as marine deposit.
Additional Information