Academic Journal
Petrography and geochemistry of carbonate rocks of the Paleoproterozoic Zaonega Formation, Russia:documentation of C-13-depleted non-primary calcite
| العنوان: | Petrography and geochemistry of carbonate rocks of the Paleoproterozoic Zaonega Formation, Russia:documentation of C-13-depleted non-primary calcite |
|---|---|
| المؤلفون: | Crne, A. E., Melezhik, V. A., Lepland, A., Fallick, A. E., Prave, A. R., Brasier, A. T. |
| المصدر: | Crne , A E , Melezhik , V A , Lepland , A , Fallick , A E , Prave , A R & Brasier , A T 2014 , ' Petrography and geochemistry of carbonate rocks of the Paleoproterozoic Zaonega Formation, Russia : documentation of C-13-depleted non-primary calcite ' , Precambrian Research , vol. 240 , pp. 79-93 . https://doi.org/10.1016/j.precamres.2013.10.005 |
| سنة النشر: | 2014 |
| مصطلحات موضوعية: | Paleoproterozoic, Carbon cycle, Non-primary calcite, Russia, Great oxidation event, Onega Basin, ATMOSPHERIC OXYGEN, ISOTOPIC EVIDENCE, NW RUSSIA, OIL-FIELD, GREENSCHIST FACIES, GREENSTONE-BELT, BALTIC SHIELD, ONEGA PLATEAU, GA, KARELIA |
| الوصف: | The ca. 2.0 Ga Zaonega Formation in the Onega Basin of NW Russia represents a deep-water, mixed siliciclastic-carbonate depositional system with voluminous mafic volcanism. It is typified by extremely organic-rich rocks (TOC > 40 wt%) and represents one of the earliest known episodes of oil/asphalt generation. These rocks have been inferred to archive one of the largest negative delta C-13 excursions in Earth history, one that followed and/or partially overlapped with the 2.2-2.06 Ga worldwide Lomagundi-Jatuli carbonate carbon isotopic excursion to high values and thought to be linked to the Paleoproteorozoic oxygenation of Earth's surface environments. In order to assess the post-depositional integrity of the carbonate carbon isotopic signal (delta C-13(carb)) of the Zaonega rocks, we examined in detail the petrography and geochemistry of eight carbonate beds (0.3-0.9 m thick) from different stratigraphic levels of the formation. The range of delta C-13 values for a single bed can be as much as 17 parts per thousand, with calcite being significantly depleted in C-13 relative to co-existing dolomite; the C-13-depleted calcite likely formed by involvement of carbon derived from diagenetic and catagenetic alteration of organic matter possibly abetted by volcanic CO2. The presence of calcite +/- talc +/- phlogopite +/- actinolite indicates metamorphic reaction of dolomite with quartz, or possibly K-feldspar, in the presence of water; commonly accompanied by degassing of C-13-enriched CO2, this caused further C-13 depletion of newly formed calcite. The least altered dolomite is documented in central parts of thick dolostone beds with variably calcitized margins. This dolomite is considered as the earliest and possibly primary carbonate phase, potentially recording the delta C-13 signal of the ambient seawater. The least-altered dolomite is found in two stratigraphic intervals exhibiting delta C-13 values of +8 and +4 parts per thousand for the middle part of the formation, and delta C-13 values of -2 and -4 parts ... |
| نوع الوثيقة: | article in journal/newspaper |
| اللغة: | English |
| DOI: | 10.1016/j.precamres.2013.10.005 |
| الاتاحة: | https://risweb.st-andrews.ac.uk/portal/en/researchoutput/petrography-and-geochemistry-of-carbonate-rocks-of-the-paleoproterozoic-zaonega-formation-russia(9971e9db-0e8f-4f63-a852-8901390a7648).html https://doi.org/10.1016/j.precamres.2013.10.005 |
| Rights: | info:eu-repo/semantics/restrictedAccess |
| رقم الانضمام: | edsbas.969C29B7 |
| قاعدة البيانات: | BASE |
| DOI: | 10.1016/j.precamres.2013.10.005 |
|---|