Diagenesis of bivalves from Jurassic and Lower Cretaceous lacustrine deposits of northeastern China

Journal article


Publication Details

Author(s): Fürsich F, Pan YH
Journal: Geological Magazine
Publisher: Cambridge University Press
Publication year: 2016
Volume: 153
Journal issue: 1
Pages range: 17-37
ISSN: 1469-5081
Language: English


Abstract


In contrast to the numerous excellently preserved arthropods, vertebrates and plants from the Mesozoic lacustrine fossil lagerstätten of northeastern China, which have calcium phosphate or organic skeletons, the preservation of taxa with a calcareous skeleton is fairly poor. Here we investigate, using a scanning electron microscope and energy dispersive X-ray spectrometer, the preservational modes of bivalves from the Jurassic Daohugou Fossil Beds of Inner Mongolia and the Lower Cretaceous Yixian Formation of eastern Liaoning. The Jurassic bivalve Ferganoconcha sibiricais preserved as strongly compressed composite moulds which contain remains of the organic periostracum. In the Yixian Formation, the bivalves Sphaerium anderssoni and Arguniella ventricosa occur as compacted internal, external or composite moulds or are preserved with a silicified shell, and rarely with a shell consisting of iron hydroxides, which had replaced pyrite during late diagenesis/weathering. Silicification produced partly fabric-replacive microcrystalline quartz and partly void-filling megaquartz crystals after the carbonate shell had been dissolved. Films of authigenic aluminosilicate minerals, partly secondarily silicified, cover the exterior and interior shell surfaces. Occasionally, early diagenetic pyrite crystals, now oxidized to iron hydroxides, filled shell cavities forming internal moulds and rarely replaced the bivalve shell. The poor preservation of the bivalves reflects the environment and water chemistry of these lakes, which were heavily influenced by volcanic processes. Frequent ash deposition and decomposition of volcanic glass particles created acidic and alkaline lake and interstitial waters, which led to early diagenetic formation of authigenic aluminosilicate minerals, ferruginous internal moulds, dissolution of shell carbonate and silicification of shells.



FAU Authors / FAU Editors

Fürsich, Franz Prof. Dr.
Naturwissenschaftliche Fakultät


External institutions with authors

Nanjing Institute of Geology and Paleontology


How to cite

APA:
Fürsich, F., & Pan, Y.-H. (2016). Diagenesis of bivalves from Jurassic and Lower Cretaceous lacustrine deposits of northeastern China. Geological Magazine, 153(1), 17-37. https://dx.doi.org/10.1017/S0016756815000242

MLA:
Fürsich, Franz, and Yan-Hong Pan. "Diagenesis of bivalves from Jurassic and Lower Cretaceous lacustrine deposits of northeastern China." Geological Magazine 153.1 (2016): 17-37.

BibTeX: 

Last updated on 2018-08-08 at 01:28