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Foraminiferal biostratigraphy and palaeoenvironmental analysis of the Mid-Cretaceous limestones in the southern Tibetan Plateau

Marcelle K. Boudagher-Fadel, Hu Xiumian, G. David Price, Sun Gaoyuan, Wang Jiangang and An Wei
Foraminiferal biostratigraphy and palaeoenvironmental analysis of the Mid-Cretaceous limestones in the southern Tibetan Plateau
Journal of Foraminiferal Research (April 2017) 47 (2): 188-207

Abstract

This study of mid-Cretaceous foraminifera from the Linzhou, the Coqen and the Xigaze Basins in the southern Tibetan Plateau has provided the first high resolution biostratigraphic description of these limestones and interpretation of their paleoenvironmental settings. The fossil assemblages are dominated primarily by orbitolinid larger benthic foraminifera. We reassessed the identification of many taxa, dividing the South Tibetan sedimentary successions of Aptian to Early Cenomanian age into eight new foraminiferal biozones (TLK1 a-h): (i) (TLK1a) a shallow reefal environment corresponding to planktonic foraminifera zone (PZ) Aptian 1-2, dominated by Palorbitolina and Praeorbitolina spp.; (ii) (TLK1b) a transgressive, reefal to forereefal environment corresponding to PZ Aptian 3, characterized by the first appearance of Mesorbitolina parva; (iii) (TLK1c) a shallow reefal to backreef environment of Late Aptian (PZ Aptian 4) age, characterized by the first appearance of Mesorbitolina texana; (iv) (TLK1d) a transgressive phase of forereef to an inner neritic environment of Albian (PZ Albian 1) age, characterized by the first appearance of Cuneolina pavonia; (v) (TLKe) an open-marine reefal environment of Albian (PZ Albian 2) age, with assemblages dominated by flat to slightly conical orbitolinids, characterized by the first appearance of Palorbitolinoides hedini; (vi) (TLK1f) a shallow, open-marine reefal to forereef environment of Middle Albian (PZ Albian 3) age, dominated by flat and convex orbitolinids, and characterized by the first appearance of Mesorbitolina aperta; (vii) (TLK1g) a reefal to forereef environment of end Albian (PZ Albian 4) age, characterized by the appearance of Conicorbitolina cf. cuvillieri and Pseudochoffatella cuvillieri, and in which Early Aptian species of Praeorbitolina cf. wienandsi have been recorded for the first time from the Late Albian; (viii) (TLK1h) a shallow reefal environment of Early Cenomanian age characterized by the first appearance of Conicorbitolina sp. A and Nezzazata conica. The eight new biozones provided biostratigraphic correlation of the Langshan, Sangzugang and Takena Formations in the Lhasa terrane, while the observed evolution of the environmentally controlled microfacies corresponds closely with the current, inferred global sea-level variation of the period. The almost continuous sedimentary sequences studied allowed previously defined orbitolinid phylogenetic linages to be confirmed.


ISSN: 0096-1191
EISSN: 1943-264X
Coden: JFARAH
Serial Title: Journal of Foraminiferal Research
Serial Volume: 47
Serial Issue: 2
Title: Foraminiferal biostratigraphy and palaeoenvironmental analysis of the Mid-Cretaceous limestones in the southern Tibetan Plateau
Affiliation: University College London, Department of Earth Sciences, London, United Kingdom
Pages: 188-207
Published: 201704
Text Language: English
Publisher: Cushman Foundation for Foraminiferal Research, Ithaca, NY, United States
References: 68
Accession Number: 2017-046401
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., geol. sketch map
N31°10'00" - N31°56'60", E84°52'00" - E85°25'00"
N29°52'60" - N29°55'00", E91°19'00" - E91°20'60"
N29°18'00" - N29°18'00", E88°24'00" - E88°24'00"
Secondary Affiliation: Nanjing University, CHN, ChinaChinese Academy of Sciences, Institute of Geology and Geophysics, CHN, China
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Cushman Foundation for Foraminiferal Research. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201725
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