Nannotax3 - ntax_mesozoic - Broinsonia galloisii

Distinguishing features:
Parent taxon (Broinsonia): Outer rim of V-units, with slight clockwise obliquity, visible on distal surface and form dark rim in LM; central-area spanned by an axial cross, grill or perforate plate. 3 tiers visible in side view.
This taxon: Small Broinsonia (<5.5µm) with broad axial cross bars.

Citation: Broinsonia galloisii (Black, 1973) Bown in Kennedy et al., 2000

Basionym: Acaenolithus galloisii Black, 1973

Taxonomic discussion: Described by Black (1973) from Upper Aptian to Middle Albian samples, with coccolith length ranging from 4.5-7.5 µm, mean length 5.7 µm. Used by Bown in Kennedy et al. (2000) for small Broinsonia coccoliths (length 4.0-5.5 µm, mean 4.7 µm), with larger forms called Broinsonia matalosa and B. viriosa (>8.0 µm). Smaller specimens (length c. 3.5 µm) were called Broinsonia cf. B. galloisii.

Geological Range:
Last occurrence (top): within Albian Stage (100.50-113.20Ma, top in Albian stage). Data source: [PRB rough estimate]
First occurrence (base): within Aptian Stage (113.20-121.40Ma, base in Aptian stage). Data source: [PRB rough estimate]

References:

Black, M. (1973). British Lower Cretaceous Coccoliths. I-Gault Clay (Part 2). Palaeontographical Society Monograph. 127: 49-112. gs

Bown, P. R. (2001). Calcareous nannofossils of the Gault, Upper Greensand and Glauconitic Marl (Middle Albian-Lower Cenomanian) from the BGS Selborne boreholes, Hampshire. Proceedings of the Geologists' Association. 112: 223-236. gs

Bralower, T. J. & Bergen, J. A. (1998). Cenomanian-Santonian calcareous nannofossil biostratigraphy of a transect of cores drilled across the Western Interior Seaway. In, Dean, W. E. & Arthur, M. A. (eds) Stratigraphy and paleoenvironments of the Cretaceous Western Interior Seaway. SEPM Concepts in Sedimentology and Paleontology . (6): -. gs

Gale, A. S. et al. (2011). The uppermost Middle and Upper Albian succession at the Col de Palluel, Hautes-Alpes, France: An integrated study (ammonites, inoceramid bivalves, planktonic foraminifera, nannofossils, geochemistry, stable oxygen and carbon isotopes, cyclostratigraphy). Cretaceous Research. 32: 59-130. gs

Jeremiah, J. (2001). A Lower Cretaceous nannofossil zonation for the North Sea Basin. Journal of Micropalaeontology. 20(1): 45-80. gs

Kanungo, S., Bown, P. R. & Gale, A. S. (2020). Cretaceous (Albian-Turonian) calcareous nannofossil biostratigraphy of the onshore Cauvery Basin, southeastern India. Cretaceous Research. 118 [2021]: 1-22. gs

Kennedy, W. J. et al. (2000). Integrated stratigraphy across the Aptian-Albian boundary in the Marnes Bleues, at the Col de Pre _-Guittard, Arnayon (Drome), and at Tartonne (Alpes-de-Haute-Provence), France: a candidate Global Boundary Stratotype Section and Boundary Point for the base of the Albian Stage. Cretaceous Research. 21: 591-720. gs

Broinsonia galloisii

References:

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