Krabi Gr

Cenozoic

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Early Paleozoic

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Krabi Gr

Period:

Paleogene, Neogene

Age Interval:

Late Eocene-Early Miocene (variable) (3)

Province:
Sibumasu: Lower Peninsula

Type Locality and Naming

Krabi basin, Krabi province. Note that the Krabi series (Brown and others, 1951) has been used for Tertiary basins in southern Thailand and the Krabi group (Javanaphet, 1969) has been used for all Tertiary basins in Thailand. Now considered "defunct" [p.42 in C. K. Morley & A. Racey, 2011, Chapter 10 Tertiary in Ridd, M.F., Barber, A.J., and Grow, M.J., editors, The Geology of Thailand, Geol. Soc. of London], but replacement terminology is not yet standardized?

Synonym: หินสมัยกระบ

[Figure: Stratigraphic section of the Tertiary beds exposed in the Bang Mark open pit SE of Krabi town. (From C K Morley & A Racey, 2011)]

Lithology and Thickness

Semi-consolidated, reddish-brown to grey sandstone, siltstone claystone, limestone with coal lenses. Thickness: 1,400 m.

Lithology Pattern:

Fine-grained sandstone

Relationships and Distribution

Lower contact

Thung Yai Gr (unconformable; Phun Phin Fm is its uppermost formataion)

Upper contact

Unnamed Quaternary

Regional extent

Krabi Basin, Lower Peninsula

GeoJSON

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Fossils

"A rich vertebrate fauna from the Wai Lek mine was described by Ducrocq et al. (1991, 1993) who considered its age to be Late Eocene. .. Accepting a Late Eocene age, Marivaux et al. (2000) noted that this is the most complete Late Eocene mammalian fauna known in Southeast Asia. … The Late Eocene age of these deposits based on their vertebrate fossils is not consistent with palynological studies carried out by Watanasak (1990). He erected a zonal scheme for Thailand and found the Wai Lek mine sequence to be in his Siam 2 Zone which he considers to be Early to Middle Miocene. … Samples collected from near the main coals in the Wei Lek and Bang Pudan mines yielded a palynomorph assemblage indicative of an Oligocene–?Early Miocene age. The abundance of Inaperturopollenites spp. may indicate an age no younger than Early Miocene (Siam-1 zone of Watanasak 1989)." (Kidd, 2011)

Age

Late Eocene–?Early Miocene assumed here.

Age Span:

Beginning stage:

Priabonian

Fraction up in beginning stage:

Beginning date (Ma):

37.99

Ending stage:

Langhian

Fraction up in the ending stage:

Ending date (Ma):

15.99

Depositional setting

Fluviatile, lacustrine, coal swamp, delta front

Depositional pattern:

Additional Information

Subdivisions: Sae Leow (1985) has divided it into 5 formations: A, B, C, D and E; Electricity Generating Authority of Thailand (1990) subdivided it into 6 informal formations, in ascending, Bang Pu Dum Fm, Pakasai Fm, Khlong Sait Fm, Khuan Muang Fm, Tha Nun Fm, and Huai Khram Fm.

Compiler:

Wen Du - modified from C. K. Morley & A. Racey, 2011, Chapter 10 Tertiary in Ridd, M.F., Barber, A.J., and Grow, M.J., editors, The Geology of Thailand, Geol. Soc. of London; Lexicon of Stratigraphic Names of Thailand of 2013.