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Khao Khwang Formation

Khao Khwang Fm

Period:

Carboniferous, Permian

Age Interval:

Upper Pennsylvanian to Middle Permian (13)

Province:
Indochina Block: Loei Fold Belt

Type Locality and Naming

Khao Kwang Platform (Saraburi region): Khao Khwang, Saraburi province by Hinthong and others (1985). Parent unit: Saraburi Gr.

[Figure: Geological map of Saraburi Group in Saraburi area, NE Thailand (Ueno and Charoentitirat, 2011).]

Synonym: หมวดหินเขาขวาง

Lithology and Thickness

Black, dark to light grey limestone with chert nodules, locally dolomitic, intercalated with pinkish brown and greenish grey shale, sandstone, tuffaceous sandstone and volcanic rocks. Thickness: 490 m

[Figure: Carboniferous and Permian facies distribution and resultant stratigraphic subdivisions on the western margin of the Indochina Block, with Saraburi Group highlighted (Ueno and Charoentitirat, 2011).]

Lithology Pattern:

Siliceous limestone

Relationships and Distribution

Lower contact

not mentioned

Upper contact

not mentioned

Regional extent

in the Saraburi area of Loei-Phetchabun Ranges and northwest of the Khorat Plateau.

[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).]

GeoJSON

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Fossils

Hinthong (1981) noted that it occupies the lower part of the Saraburi Group based mainly on the occurrence of Early Permian fusulines, brachiopods, bivalves, trilobites, bryozoans and crinoids. In more recent work, Assavapatchara et al. (2006) preferred a Middle Permian age (around Murgabian) for the Khao Khwang Fm based on fusuline occurrences from the Khao Somphot area to the east of Chai Badan in northeastern Lop Buri Province (Nakornsri 1981; Wielchowsky & Young 1985; Chonglakmani & Fontaine 1992; Dawson et al. 1994; Charoentitirat 2002a). From this area, moreover, Udchachon et al. (2007) recently reported the presence of Alatoconchidae, a unique Permian giant bivalve whose palaeoecological peculiarities have been discussed by Isozaki (2006), together with Midian fusulines. In addition to these Permian fusulines, a possible Gzhelian (Late Pennsylvanian) fusuline fauna with the solitary rugose coral Sestrophyllum was discovered from the Khao Somphot area (Fontaine et al. 1996a) (Ueno and Charoentitirat, 2011).

Age

Lower Permian (Sakmarian) by Hinthong and others (1985), Upper Pennsylvanian to Middle Permian by Ueno and Charoentitirat (2011)

Age Span:

Beginning stage:

Asselian

Fraction up in beginning stage:

Beginning date (Ma):

298.88

Ending stage:

Wordian

Fraction up in the ending stage:

Ending date (Ma):

268.80

Depositional setting

Shallow-marine platform environment

[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).]

Depositional pattern:

Additional Information

Remarks: This formation was previously mapped as part of the Ratburi Group (Hinthong and others, 1985).

Compiler:

Wen Du -modified from Ueno K. & Charoentitirat T., 2011, Chapter 5 Carboniferous and Permian in Ridd, M.F., Barber, A.J., and Grow, M.J., editors, The Geology of Thailand, Geol. Soc. of London. And Lexicon of Stratigraphic Names of Thailand of 2013