Si Phai Fm

Period:

Devonian

Age Interval:

Emsian-Frasnian, (2)

Province:
Viet Bac

Type Locality and Naming

Stratotype in the section passing through Si Phai Village of the Dong Van – Nho Que section (Hai Giang Province)

Lithology and Thickness

Medium- and thin-bedded, dark-colored and pinkish-grey limestone, interbedded with clayey limestone, shale, cherty shale, cherty limestone and shale containing organic matter; 350 m thick.

Lithology Pattern:

Limestone

Relationships and Distribution

Lower contact

Conformable on the Mia Le Fm

[Figure: Mia Le-Si Phai Segment of Lung Cu – Ma Le geological section (outcrop photo) (images courtesy of Prof. Ta Hoa Phuong, Vietnam Natl. Univ. Hanoi)]

Upper contact

Conformably overlain by the Toc Tat Fm

Regional extent

Distributed in some areas of the Ha Giang Province

GeoJSON

null

Fossils

Lower part of formation has dacryoconarids (tentaculites) belong to the Nowakia acuaria Zone. In higher levels, N. zhichovensis through N. richteri have been found. Conodonts of Pol. excavatus through Pol. serotinus Zones. Cherty shale beds of the upper part have Nowakia otomari, and uppermost has Homoctenus shell remains.

[Figure: Si Phai Fm: Conodonts and Tentaculites fossils (images courtesy of Prof. Ta Hoa Phuong, Vietnam Natl. Univ. Hanoi)]

Age

Faunal assemblages are from Emsian to Frasnian.

Age Span:

Beginning stage:

Emsian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

410.51

Ending stage:

Frasnian

Fraction up in the ending stage:

0.5

Ending date (Ma):

375.00

Depositional setting

Depositional pattern:

Additional Information

Compiler:

Tran Van Tri and Vu Khuc (Editors; Geology and Earth Resources of Viet Nam, General Dept. of Geology and Minerals of Viet Nam; completed in Dec., 2011), with additional details from Tong-Dzuy Thanh and Vu Khuc (Editors; Stratigraphic Units of Viet Nam, 2^nd edition; 2011; English edited by A. Boucot).