Pha Nok Khao Fm
Type Locality and Naming
Pha Nok Khao Platform (Khon San region; south of Loei region): The type locality is at Pha Nok Khao in southernmost Loei Province (DMR 1992).
Synonym:
[Figure: Late Paleozoic major facies subdivisions on the western margin of the Indochina Block by Ueno and Charoentitirat (2011). (Slightly modified from Wielchowsky & Young 1985).]
Lithology and Thickness
Consists chiefly of massive to thick-bedded limestone with nodular or layered chert in some levels. Minor shale intercalations are also locally observed. Over 1000 m, but the detailed stratigraphy of the type section has not yet been studied.
Relationships and Distribution
Lower contact
The formation probably conformably overlies the Huai Som Fm although they may be partly heteropic facies. However, a partly-regional unconformity spanning lower-Lower Permian is indicated on the age-facies figure of Ueno and Charoentitirat 2011.
Upper contact
Overlain by the Hua Na Kham Fm.
Regional extent
Apart from the Pha Nok Khao area, the formation is also present to the west of Khon San and locally on the eastern margin of the Nam Duk Basin.
[Figure: Distribution of Carboniferous and Permian in NE Thailand. Data mainly based on 1:1 million scale geological map of Thailand (DMR 1999) with minor modifications (Ueno and Charoentitirat 2011).]
[Geo-JSON omitted – would overlap other set.]
GeoJSON
Fossils
Fossils include fusulines, the Foraminifers Neoendothyra reicheli, Kahlerina ussurica, Dunbarula aff. palaeofusulinaeformis, Codonofusiella gubleri, Chusenella cf. crassa, Sumatrina longissima, Colania douvillei, Lepidolina multiseptata, Verbeekina verbeeki and Pseudodoliolina pseudolepida, the Corals Ipciphyllum subelegans, I. phadaengensis and Multimurinus fontainei and the Calcareous Alga Mizzia velebitana.
Age
Depositional setting
Additional Information