ScienceAsia 33 (2007): 371-381 |doi: 10.2306/scienceasia1513-1874.2007.33.371

Depositional Environments of Permian Rocks of the Khao Khad Formation in Central Thailand

Sarawuth Thambunya,^a* Visut Pisutha-Arnond^b and Chaiyudh Khantaprab^c

 
ABSTRACT:    The Khao Khad Formation of Saraburi Group in the central part of Thailand is the sequences of limestone, dolomitic limestone and silty shale with nodular and banded cherts. The investigation of the sedimentary sequences has been undertaken on the basis of lithological characteristics and sedimentary structures. Twenty nine measured sections were conducted in three study areas in the vicinity of Khao Khad, Khao Chan and areas along Pak Chong – Khao Yai route. Altogether 312 sampling locations and 539 rock specimens were examined in this study. Fifteen rock units can be distinguished from the sedimentary sequence including: a) calcilutite with nodular chert, b) algal biolithite, c) crinoidal calcirudite, d) crinoidal calcirudite with nodular chert, e) crinoidal calcirudite with banded dolomite, f) grade-bedded calcarenite with banded chert, g) fusulinid-bearing fine calcirudite, h) coral biolithite, i) laminated dolomitic calcarenite, j) fusulinid and intraclasts-bearing calcirudite, k) fenestral and disturbed dolomitic calcilutite, l) fusulinid bearing calcarenite, m) intraclasts-bearing calcarenite, n) argillaceous limestone with silty shale, and o) cross-laminated calcarenite. The Khao Khad Formation was most likely deposited during a major transgressive and regressive cycle of seawater during the Lower to Middle Permian time in the marine shelf condition under sub-environments of intertidal to subtidal zones near shore, subtidal zone of lagoon, shallow platform, barrier bar or shoal and foreslope of barrier bar.

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^a TPI Polene Public Company Limited. 299 Moo 5, Mitraparp Road, Tabkwang, Kaeng Khoy, Saraburi 18260, Thailand.
^b Department of Geology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
^c Higher Education Development Project. Building 5, Former Srinakharinwirot Pathumwan Campus, Henri Dunant Road, Pathumwan, Bangkok 10330, Thailand.

* Corresponding author, E-mail: tsarawuth@gmail.com

Received 6 Feb 2007, Accepted 4 Jun 2007