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Mai Hung Formation

Mai Hung Fm

Period:

Jurassic

Age Interval:

Middle Jurassic (early Aalenian) (8)

Province:
NW Thailand – Inthanon Zone

Type Locality and Naming

Mae Hong Son basin (NW Thailand), near Myanmar, north of Mae Ping Fault. Named after Mai Hung village, Mueang Mae Hong Son district; type section is at a limestone cave, about 1.5 km along the track SSE of Mai Hung village (grid reference 878067 on map sheet 4547-II). Middle formation in the Huai Pong Gr.

Synonym: หมวดหินไม้ฮงุ

[Figure: The three sedimentary basins in which the marine Jurassic occurs, and their relationships to the main faults which might subsequently have displaced them (MYF, Mae Yuan Fault; MPF, Mae Ping Fault; TPF, Three Pagodas Fault; KMF, Khlong Marui Fault). The main outcrop areas of non-marine Jurassic rocks are also shown. In some areas, particularly on Peninsular Thailand, the Jurassic succession contains both marine and non-marine facies (redrawn from Meesook 1994; Charusiri et al. 2002, by Meesook A. & Saengsrichan W., 2011, Page 152).]

Lithology and Thickness

Sandy limestone. Well-bedded sandy limestone with oncolites in the lower part (Unit C); a fossiliferous calcareous siltstone (unit D); massive grey limestones in the middle part (Unit D); and sandy limestone in the upper part (Unit E). Thickness: at the type section and 70 m at Huai Ta Pu Kho in Mae Sot District, Tak Province.

Lithology Pattern:

Sandy limestone

Relationships and Distribution

Lower contact

The lower contact is partly conformable with the Pa Lan Fm (Pa Lan Fm).

Upper contact

Grading into sandstone of the overlying Kong Mu Fm.

Regional extent

Mae Hong Son basin (northern part of Mae Hong Son – Kanchanaburi Basin); Northern Region: Mae Hong Son and Tak provinces

GeoJSON

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Fossils

An Aalenian age is given for the formation on the basis of the foraminifer Timidonella sarta Bassoullet et al.

Age

Spans the lower Aalenian (Fig. 7.3 in Meesook & Saengsrichan, 2011)

Age Span:

Beginning stage:

Aalenian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

174.15

Ending stage:

Aalenian

Fraction up in the ending stage:

0.5

Ending date (Ma):

172.22

Depositional setting

Shallow marine, neritic zone

Depositional pattern:

Additional Information

Compiler:

Wen Du - modified from Assanee Meesook & Wirote Saengsrichan, 2011, Chapter 7 Jurassic 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.