Research paper

Isotopic and mineralogical variations in the infill of Chondrites from organic-rich black shale (Posidonia Shale, Germany) for assessing the mode of colonization

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KENTARO IZUMI
Department of Earth and Planetary Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. izumi@eps.s.u-tokyo.ac.jp
Corresponding author

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ABSTRACT

The compositional variations of the infill of Chondrites within the Toarcian (Lower Jurassic) organic-rich black shale of southern Germany were evaluated on the basis of organic carbon-isotope and XRD analyses of the infill, surrounding black shale, and overlying greenish-grey mudstone for assessing the mode of colonization by the trace-maker. Both carbon-isotope rations and the mineralogical compositions (i.e., quartz/calcite peak-height-ratio) of the infill show much larger variations than those of the overlying mudstone and ambient black shale. These limes of evidence strongly confirm the prolonged upward migration model, and the short-term opportunistic colonization model is not likely in this case. Although the obtained data cannot directly provide any evidence of the chemosymbiotic trace-maker model, this study also indicates that the isotopic and mineralogical variations recorded in the infill of Chondrites can be used as good indicators to assess the trace-maker’s colonization style, furthermore to distinguish opportunistic/climax trace fossil.

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Keywords:  Trace fossils, organic carbon-isotope, mineralogy, colonization, black shale.

How to cite:  Izumi, K. 2014. Isotopic and mineralogical variations in the infill of Chondrites from organic-rich black shale (Posidonia Shale, Germany) for assessing the mode of colonization. Spanish Journal of Palaeontology, 29 (2), 107-116.

Received 20 March 2013, Accepted 21 August 2013, Published 31 December 2014

https://doi.org/10.7203/sjp.29.2.17493

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