Amgueddfa Cymru - National Museum Wales

Brachiopods and their application to Cambrian stratigraphy

Staff: L.E. Popov

Introduction

Linguliformean brachiopods are important but inadequately known components of the benthic Cambrian faunas. This project is dedicated mostly to the Late Cambrian brachiopod faunas from the Kyrshabakty Section in Malyi Kazakhstan, which is considered as a potential candidate for the Global Boundary Stratotype Section and Point (GSSP) of the second stage of the Furongian Series, and from the Lawson Cove section in the Ibex area of Millard County, Utah, USA, proposed as the GSSP for the base of the highest stage of the Cambrian System. Lingulate brachiopods were strongly affected by the extinction at the base of the Paibian Stage, and distinctive components of the micromorphic lingulate associations like Linnarssonia, Neotreta, Picnotreta, Rhondellina, Stilpnotreta and some others vanished completely before the Paibian. Characters of the recovery and dispersion of the linguliformean brachiopod faunas are important for the better understanding of the Late Cambrian palaeogeography and their study may contribute to the elaboration of the global biostratigraphical framework for the Upper Cambrian.

[image: Leonid Research image]

Easterly view of the Kyrshabakty section showing measured intervals in metres, the FAD of trilobite species diagnostic of the Stage boundaries, and position of potential GSSP levels within the section. Red dashed line shows horizon corresponding to the FAD of Agnostotes orientalis. Red numerals show position of fossil localities which contain Agnostotes orientalis: 1, sample 2004; 2, sample 2004-2; 3, sample 2007.

This is the ongoing project dedicated to the taxonomical study of a number of Cambrian brachiopod faunas across the world and their biostratigraphical application for subdivision and long range correlation of rock units (Alvaro et al. 2008). Recently published papers were also focused on the study of biostratigraphical sequences in the Upper Cambrian sections presented as potential Global Boundary Stratotype Section and basal Point (GSSP) in Utah, USA (Miller et al. 2006) and in Malyi Karatau, Kazakhstan (Ergailev et al. 2008). Another Cambrian fauna currently under the study in cooperation with L. Holmer from the Uppsala University was sampled by N.C. Hughes (University of California) in Himalayans, northern Pakistan.

References

James F. Miller, J. F., Ethington, R. L, Evans, K. R., Holmer, L. E., Lochd, J. Popov, L. E., Repetski, J. E., Ripperdan, R. L., and F. Taylor, J. F., 2006. Proposed stratotype for the base of the highest Cambrian stage at the first appearance datum of Cordylodus andresi, Lawson Cove section, Utah, USA. Palaeoworld, 15, 384–405.

Ergaliev, G. Kh., Zhemchuzhnikov, V., G. Ergaliev, F.G, Popov, L.E., Ghobadi Pour, M. and Bassett, M.G. 2008. Trilobite biostratigraphy and biodiversity patterns through the Middle-Upper Cambrian transition in the Kyrshabakty section, Malyi Karatau, southern Kazakhstan, 91-98. In I.Rábano, I., Gozalo, R. and García-Bellido D. (eds), Advances in trilobite research. Cuadernos del Museo Geominero, 9 . Instituto Geol ógico y Minero de Espa ña, Madrid, 448 pp.

Álvaro, J.J., Ezzouhairi, H., Ait Ayad, N., Charif, A, Popov L. and Luisa Ribeiro, L. 2008. Short-term episodes of carbonate productivity in a Cambrian uplifted rift shoulder of the Coastal Meseta, Morocco. Gondwana Research, 14 , 410–428.