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Trang Formation

Trang Fm

Period:

Neogene

Age Interval:

Middle Miocene (1,2)

Province:
Andaman Sea: Mergui Basin

Type Locality and Naming

At the Trang well between interval 2,670-5,110 feet. The Trang formation was first named by Nakanart and Mantajit (1983). Information below is combined with Polachan (1988). Parent unit: Mergui Gr.

Synonym: หมวดหินตรัง

[Figure 1: Map of the Mergui Basin showing the main structural features including basin depocentres, based on an extensive grid of 2D seismic reﬂection data. (From C K Morley & A Racey, 2011)]

Lithology and Thickness

Mainly grey glauconitic shales in the lower part, and turbidites in the upper part. Thickness: 732 m at the type section, 231 m at the E-1 well.

[Figure 2: Stratigraphy and cross-section through the Mergui Basin, Andaman Sea, based on data in Polachan & Racey (1994) and Andreason et al. (1997). (a) Oligocene–Recent stratigraphy of the Mergui Basin; (b) stratigraphy of the syn-rift section (Oligocene–early Miocene) schematically illustrating the east–west variation in stratigraphy across the basin and the effect of rift-basin highs (e.g. Central High horst block) on large-scale distribution of sedimentary facies, modiﬁed from Andreason et al. (1997); (c) east–west cross-section through the Mergui Basin illustrating the typical half-graben geometries of the basin (modiﬁed from Polachan & Racey 1994). (From C K Morley & A Racey, 2011)]

Lithology Pattern:

Sandy claystone

Relationships and Distribution

Lower contact

Kantang Fm or Tai Fm in South Mergui Basin, or Surin Fm in North Mergui Basin (conformable)

Upper contact

Thalang Fm (unconformable)

Regional extent

Andaman Sea: Mergui Basin. Correlation: Baong Fm of North Sumatra Basin

GeoJSON

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Fossils

Age

Middle Miocene (but begins in upper-Middle Miocene in North Mergui, where it is the distal equivalent to the sands of the Surin Fm.) For graphic purposes, put here as upper-Middle Miocene, with Surin Fm below.

Age Span:

Beginning stage:

Serravallian

Fraction up in beginning stage:

Beginning date (Ma):

13.82

Ending stage:

Tortonian

Fraction up in the ending stage:

Ending date (Ma):

11.63

Depositional setting

Bathyal deposits

Depositional pattern:

Additional Information

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.