Lampang Gr
Period:
Triassic
Age Interval:
Lower to Upper Triassic (Scythian to Norian) (11)
Province:
Sukhothai Fold Belt
Type Locality and Naming
Type area: Lampang and Phrae provinces, central part of the Northern Region of Sukhothai Fold Belt. Subdivisions: Chaodumrong and Burrett (1997) subdivided it into 7 formal formations: Phra That Fm, Pha Kan Fm, Hong Hoi Fm, Doi Long Fm, Pha Daeng Fm, Kang Pla Fm, and Wang Chin Fm. Chonglakmani (2011) proposed that this group consists of 4 formal formations: Phra That Fm, Pha Kan Fm, Hong Hoi Fm, and Doi Long Fm; and assigned the Pha Daeng Fm, Kang Pla Fm, and Wang Chin Fm to his new Song Gr. (used here)
Synonym: กลุ่มหินลำปาง
[Figure 1 : Generalized distribution of different Triassic sedimentary environments and some of the more important lithostratigraphic units, and their relations to the terranes. (The geology of Thailand, 2011) page 146]
Lithology and Thickness
Consists of 2 mega sequences of mainly fine-grained clastic rocks, from red beds up to platform limestones and turbiditic sandstone and mudstone. See component formations. Total thickness: 3,000 m.
Lithology Pattern:
Clayey limestone
Relationships and Distribution
Lower contact
Ngao Gr (conformable)
Upper contact
Pha Daeng Fm (conformable)
Regional extent
Lampang-Phrae basin, west part of the Northern Region of Sukhothai Fold Belt.
[Figure 2 : Generalized distribution of marine Triassic sedimentary rocks in Thailand (in purple) (modified after Mantajit 1999). (The geology of Thailand, 2011) page 138]
GeoJSON
null
Fossils
See component formations.
Age
Early Triassic (mid-Griesbachian) through early Carnian in Fig. 6.2 of Chonglakmani, C.P., 2011.
Age Span:
Beginning stage:
Induan
Fraction up in beginning stage:
0.25
Beginning date (Ma):
251.38
Ending stage:
Carnian
Fraction up in the ending stage:
0.3
Ending date (Ma):
234.44
Depositional setting
Shallow to deep marine environments
Depositional pattern:
Additional Information
Correlation: Semanggol Fm in Malaysia
Compiler:
Wen Du - modified from- Chonglakmani, C.P., 2011, Chapter 6 Triassic 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.