DOI: 10.1016/j.gloplacha.2016.07.010
论文题名: Diagenesis of echinoderm skeletons: Constraints on paleoseawater Mg/Ca reconstructions
作者: Gorzelak P. ; Krzykawski T. ; Stolarski J.
刊名: Global and Planetary Change
ISSN: 0921-8181
出版年: 2016
卷: 144 起始页码: 142
结束页码: 157
语种: 英语
英文关键词: Calcite
; CL
; Diagenesis
; FESEM
; Mg/Ca
; XANES
Scopus关键词: Biological materials preservation
; Biomineralization
; Calcite
; Cathodoluminescence
; Chlorine
; Geochemistry
; Musculoskeletal system
; Repair
; Seawater
; Sedimentology
; Diagenesis
; FESEM
; Geochemical composition
; Nano-composite structure
; Physiological factors
; Porous microstructure
; Skeletal compositions
; XANES
; Magnesium
; algae
; Bryozoa
; Echinodermata
; Pelmatozoa
英文摘要: One of the most profound environmental changes thought to be reflected in chemical composition of numerous geological archives is Mg/Ca ratio of the seawater, which has varied dramatically throughout the Phanerozoic. Echinoderms that today typically form high magnesium calcite skeletons are increasingly being utilized as a proxy for interpreting secular changes in seawater chemistry. However, accurate characterization of the diagenetic changes of their metastable high magnesium calcite skeletons is a prerequisite for assessing their original, major-element geochemical composition. Here we expand the existing models of diagenesis of echinoderm skeleton by integration of various analytical methods that up to now rarely have been used to assess the diagenetic changes of fossil echinoderms. We validated the preservation of a suite of differently preserved echinoderm ossicles, mostly crinoids, ranging in age from the Cambrian through Recent. In 13 of 99 fossil echinoderm ossicles we found well-preserved porous microstructure (stereom), non-luminescent behaviour or blotchy dark color in cathodoluminescence, and distinct nanostructural features (layered and nanocomposite structure). Moreover, in representatives of such preserved samples, distribution of sulphates associated with organic matter is identical to those in Recent echinoderms. Only such ossicles, despite of local micrometer-scale diagenetic changes, were herein considered well-preserved, retaining their original major-element skeletal composition. By contrast, majority of samples show transformation to the stable low magnesium calcite that leads to obliteration of the primary geochemical and micro/nanostructural features and is accompanied with increase in cathodoluminescence emission intensity. Using only well-preserved fossil echinoderm samples, we found purely random variation in Mg/Ca in echinoderm skeletons through the observed time series; any periodicities in echinoderm skeletal Mg/Ca ratio which might be related to the secular transitions in calcite and aragonite seas were not confirmed. These findings suggest that, in contrast to some groups of organisms with relatively weak control over their biomineralization (such as algae, sponges, and bryozoans), in which polymorph mineralogies consistently changed according to the seawater type, application of fossil echinoderms, in particular crinoids, to seawater Mg/Ca reconstructions is unreliable. These data emphasize a key-role of physiological factors (the so-called vital effects) in echinoderm biomineralization. © 2016 Elsevier B.V.
URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979743647&doi=10.1016%2fj.gloplacha.2016.07.010&partnerID=40&md5=14a517c141f0ccdcf73d8fce101148d6
Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/11647
Appears in Collections: 全球变化的国际研究计划 气候变化与战略
There are no files associated with this item.
作者单位: Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, Warsaw, Poland
Recommended Citation:
Gorzelak P.,Krzykawski T.,Stolarski J.. Diagenesis of echinoderm skeletons: Constraints on paleoseawater Mg/Ca reconstructions[J]. Global and Planetary Change,2016-01-01,144.