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Title: | Testing carbonate chemostratigraphy across differentiated ancient shallow-platform environments (Early Kimmeridgian, S Iberia) | Authors: | Coimbra, Rute Marques, Beatriz Olóriz, Federico |
Keywords: | Palaeoenvironment; Carbonate chemostratigraphy; Shallow-water carbonates; Diagenesis; Kimmeridgian | Issue Date: | 2019 | Publisher: | Elsevier | Project: | This research was supported by Projects CGL2008-05251-E and CGL2012-39835 (MINECO) and the Research Group RNM-178, Junta de Andalucía, Spain. R. Coimbra is currently supported by the Post- Doctoral Fellowship SFRH/BPD/92376/2013 (Fundação para a Ciência e a Tecnologia, Portugal) and the research units GeoBiotec - UID/GEO/04035/2013 and MARE- UID/MAR/04292/2013. | Serial title, monograph or event: | Geoscience Frontiers | Volume: | 10 | Issue: | 6 | Abstract: | Shallow-platform settings with marked differences in paleoplatform bottom physiography influence the degree of connection with oceanic waters and overall circulation patterns, even when sharing the same palaeoclimatic conditions. Two Kimmeridgian shallow-marine settings have been explored to test the sensitivity and reliability of carbonate chemostratigraphy to detect such differences. An integrated overview of the obtained elemental trends depicted four major facies, shared along specific stratigraphic intervals of both depositional records. Diagenesis obliterated original geochemical signals only throughout the siliciclastics-rich interval, corresponding to the most landward setting. For the remaining facies, elemental features could be attributed to the differential action of forcing mechanisms operating along the south-Iberian paleomargin during Kimmeridgian times. The highest degree of continental influence can be recognized by a strong relationship between Fe and Mn for the most proximal setting, which fades out along the mixed carbonate-fine siliciclastic rhythmic deposition in more open settings. A characteristic geochemical signature of progressively more positive d13C values and significantly higher Sr content is identified for the interval dominated by biogenic sponge buildups. Such a local response is related to local forcing by upwelling in the surroundings of a coral fringe. The geochemical signature of a hydrothermal origin can be clearly differentiated from the influence of mere terrigenous pulses. Accordingly, the decoupling of Fe and Mn along marginal settings is the clue to detecting major events of palaeogeographic restructuring. Observed temporal variations in Mg content along both studied sections are attributed to tectonic activity influencing nearshore/coastal water masses. By integrating chemostratigraphic information and complementary evidence, the palaeoenvironmental mechanisms promoting differentiated sedimentary records along ancient subtropical, shallow, coastal settings can be disentangled. | URI: | https://hdl.handle.net/10316/107004 | ISSN: | 16749871 | DOI: | 10.1016/j.gsf.2019.03.006 | Rights: | openAccess |
Appears in Collections: | I&D MARE - Artigos em Revistas Internacionais FCTUC Ciências da Terra - Artigos em Revistas Internacionais |
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Testing carbonate chemostratigraphy across differentiated ancient shallow-platform environments.pdf | 5.41 MB | Adobe PDF | View/Open |
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