Geochemistry of black shales from Breitbach Creek
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| Formato: | Dataset Open Access |
| Lenguaje: | en |
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PANGAEA
1999
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| _version_ | 1867170988496519168 |
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| author | Wortmann, Ulrich G Hesse, Reinhard Zacher, Katharina |
| author_facet | Wortmann, Ulrich G Hesse, Reinhard Zacher, Katharina |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Lower Cretaceous sediments are frequently characterized by a well expressed cyclicity. While the processes influencing environments above the carbonate compensation depth (CCD) are reasonably well understood, almost nothing is known about the deep ocean. Cretaceous sub-CCD sediments from the Tethys and Atlantic Oceans typically show rhythmic black/green shale successions. To gain insight into the nature of these black/green shale cycles, we performed detailed geochemical analyses (X-ray fluorescence, Rock-Eval and reactive iron analysis) on a 3 m long section of latest Aptian age. The major-element distribution of the analyzed shale sequence indicates a periodic change from a high-productivity and well-oxygenated green shale mode to a low-productivity oxygen-deficient black shale mode. It is proposed here that the preservation of organic matter was dependent on the strength of salinity-driven deepwater generation. Furthermore, the data show that the Corg content covaries with changes in the detrital composition. Therefore we hypothesize that Tethyan deepwater circulation was sensitive to changes in the monsoonal system. Time series analysis suggests that these changes are periodic in nature, although we are currently unable to prove that the dominant periodicity is related to the precession component of the Milankovitch frequencies. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_856738 |
| institution | PANGAEA |
| language | en |
| publishDate | 1999 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Geochemistry of black shales from Breitbach Creek Wortmann, Ulrich G Hesse, Reinhard Zacher, Katharina Aluminium; Barium/Aluminium ratio; Bavarian Alps, Germany; Breitenbach_Creek; Calcium/Aluminium ratio; Calcium carbonate; Iron/Aluminium ratio; Magnesium/Aluminium ratio; Manganese/Aluminium ratio; OUTCROP; Outcrop sample; Phosphorus/Titanium ratio; Potassium/Aluminium ratio; SECTION, height; Silicon/Titanium ratio; Sodium/Aluminium ratio; Strontium/Aluminium ratio; Sulfur, total; Titanium/Aluminium ratio; Zirconium/Aluminium ratio Lower Cretaceous sediments are frequently characterized by a well expressed cyclicity. While the processes influencing environments above the carbonate compensation depth (CCD) are reasonably well understood, almost nothing is known about the deep ocean. Cretaceous sub-CCD sediments from the Tethys and Atlantic Oceans typically show rhythmic black/green shale successions. To gain insight into the nature of these black/green shale cycles, we performed detailed geochemical analyses (X-ray fluorescence, Rock-Eval and reactive iron analysis) on a 3 m long section of latest Aptian age. The major-element distribution of the analyzed shale sequence indicates a periodic change from a high-productivity and well-oxygenated green shale mode to a low-productivity oxygen-deficient black shale mode. It is proposed here that the preservation of organic matter was dependent on the strength of salinity-driven deepwater generation. Furthermore, the data show that the Corg content covaries with changes in the detrital composition. Therefore we hypothesize that Tethyan deepwater circulation was sensitive to changes in the monsoonal system. Time series analysis suggests that these changes are periodic in nature, although we are currently unable to prove that the dominant periodicity is related to the precession component of the Milankovitch frequencies. |
| title | Geochemistry of black shales from Breitbach Creek |
| topic | Aluminium; Barium/Aluminium ratio; Bavarian Alps, Germany; Breitenbach_Creek; Calcium/Aluminium ratio; Calcium carbonate; Iron/Aluminium ratio; Magnesium/Aluminium ratio; Manganese/Aluminium ratio; OUTCROP; Outcrop sample; Phosphorus/Titanium ratio; Potassium/Aluminium ratio; SECTION, height; Silicon/Titanium ratio; Sodium/Aluminium ratio; Strontium/Aluminium ratio; Sulfur, total; Titanium/Aluminium ratio; Zirconium/Aluminium ratio |
| url | https://doi.org/10.1594/PANGAEA.856738 |