Carbon, oxygen and strontium isotope composition of Plattenkalk from the Upper Jurassic Wattendorf Konservat-Lagerstätte (Franconian Alb, Germany)
Keywords:
Jurassic, Plattenkalk, isotopes, correlation, aged seawaterAbstract
The oldest Jurassic (Kimmeridgian) Plattenkalk occurs in Wattendorf on the northern Franconian Alb (southern Germany). It is a 15 m thick alternation of laminated dolomite and limestone, interbedded with carbonate debris layers in a depression ~2 km across and a few tens of metres deeper than the surrounding microbial-sponge reefs. The Plattenkalk overlies a few tens of metres of microbial-sponge biostrome facies and bedded, micritic basinal limestone. The bulk-rock stable isotopes of the micritic basinal facies gradually change from normal marine (δ13C ~ +2‰, δ18O ~ –2‰ VPDB) to lower values (δ13C ~ 0‰, δ18O ~ –6‰) in a ~ 40 m thick interval including Plattenkalk and suggest ageing of the bottom waters. The surrounding reefs are isotopically nearly invariant (δ13C ~ +2‰, δ18O ~ –2‰ VPDB). An isotope anomaly (δ13C of > ~ –9‰) is restricted to the basinal facies and is most pronounced in the biostrome facies. This indicates methanogenesis, which is documented in negative δ13C in dedolomite, calcite-cemented dolomite and calcite concretions and occurred probably mainly below seabed. The Konservat-Lagerstätte was probably deposited near an oxygen minimum zone in a water column with low productivity of organic material. Dolomite is in isotopic equilibrium with Plattenkalk and was probably deposited as protodolomite from chemically modified, aged seawater. 87Sr/86Sr ratios of bulk carbonate are often slightly radiogenic, probably due to random analytical sample contamination by clay minerals. Belemnite and some matrix 87Sr/86Sr is slightly lower than that of Kimmeridgian seawater, either caused by basin restriction or by fluids derived from the diagenesis of Oxfordian rocks below. An equivalent Upper Kimmeridgian depression ~23 km distant and a somewhat younger Konservat-Lagerstätte in Poland show a δ13C isotope anomaly below the main fossil beds. Isotopic evidence for saline bottom waters, the current interpretation, is lacking. This study also shows that micritic carbonates can preserve their early diagenetic, marine δ18O signal, which is correlatable over tens of kilometres.Downloads
Published
Issue
Section
License
Submission of a manuscript implies that the work described has not been published before (except in the form of an abstract or a part of a lecture, review or thesis) and that is not under consideration for publication elsewhere. If and when the manuscript is accepted for publication, the authors agree to transfer the copyright of their work to the publisher. The copyright covers the exclusive rights to reproduce and distribute the work, all translation rights as well as the rights to publish the work in any electronic form.
Copyright allows you to protect your original material and stop others from using your work without your permission. It means others will generally need to credit you and your work properly, increasing its impact. If you choose to assign copyright to us, as part of the publication process, you will be asked to sign a publishing agreement. This will be after your manuscript has been through the peer-review process, been accepted, and moves into production.
Authors and authors responsibilities: Authorship should be limited to those who have made a significant contribution to the manuscript content. All those who have made significant contribution should be listed as co-authors. It is declared by the author(s) that manuscripts in all categories submitted to the journal and subjects to peer-review have not been published or submitted to any other journal or book. If the manuscript is written by several authors, the corresponding author should be indicated. It is declared that the corresponding author represents all the co-authors in certifying that all of them contributed meaningfully in preparation of the study, and that the final submitted version of the text is approved by all the co-authors. The author(s) should not publish in their study any copied part of the text and or figures from other sources without proper citation or permission (if necessary) – which is plagiarism – and stay in conflict with basal requirements of the authorship. All the authors are obliged to participate in peer review process, providing retractions or corrections of mistakes. The author(s) should indicate (the best in acknowledgements) the financial support and/or program within which the study has been prepared. Affiliation (all authors/co-authors) and corresponding address (main author) must be clearly stated.
Publication ethics and malpractice requirements: the Volumina Jurassica seeks to publish original work in the best possible form and to the highest possible standards. It is necessary to agree upon standards of expected ethical behavior for all parties involved in the act of publishing (authors, editors, peer reviewers, publisher). The Volumina Jurassica ethic statements are based on the guidelines and standards developed and published by the Committee on Publication Ethics (COPE- http://publicationethics.org/).
Anti-plagiarism Policy: Plagiarism is understood in the sense of the “use another person’s ideas or work and pretend that it is own’ (Cambridge Dictionary) or “the practice of taking someone else’s work or ideas and passing them off as one’s own” (Oxford Dictionaries), self-plagiarism (re-use of significant parts of one’s own copyrighted work without citing the original sources).
All articles in the Volumina Jurassica are supposed to be original. Authors submitting manuscript declare that submitted manuscript is original and has not been prepared from other published material. A paper should contain sufficient detail and references to permit others to replicate the work; any used information resources (phrases, data, images) must be appropriately cited or quoted.
Editors: the Volumina Jurassica editor is responsible for deciding which of the articles submitted to the journal should be published. The Volumina Jurassica editor will accept and evaluate manuscripts for their intellectual content only. Editors must not disclose any information about a submitted manuscript to anyone than stakeholders. The excluded from publication procedure are manuscripts which are beyond the scope of the interest of the journal (i.e. presenting the themes not related with the Jurassic System), and those evidently showing research misconduct (published elsewhere before, plagiarisms or bearing fundamental research mistakes). Unpublished manuscripts or materials must not be used in an editor’s own research. All submitted manuscripts will be considered for publication free of charge. When an author discovers a significant error or inaccuracy in own published work, it is the author’s obligation to promptly notify the Publisher and cooperate with the editor to retract or correct the paper.
