کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4689150 | 1636034 | 2015 | 68 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
On the origin of a phosphate enriched interval in the Chattanooga Shale (Upper Devonian) of Tennessee-A combined sedimentologic, petrographic, and geochemical study
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: On the origin of a phosphate enriched interval in the Chattanooga Shale (Upper Devonian) of Tennessee-A combined sedimentologic, petrographic, and geochemical study On the origin of a phosphate enriched interval in the Chattanooga Shale (Upper Devonian) of Tennessee-A combined sedimentologic, petrographic, and geochemical study](/preview/png/4689150.png)
چکیده انگلیسی
Deposited atop a sequence boundary that separates the two shale units, the PhBS unit represents a transgressive systems tract and probably was deposited in shallower water than the underlying PBS interval. The higher phosphate content in the PhBS is interpreted as the result of a combination of lower sedimentation rates with reworking/winnowing episodes. Three types of phosphatic beds that reflect different degrees of reworking intensity are observed. Strong negative Ce anomalies and abundant secondary marcasite formation in the PhBS suggests improved aeration of the water column, and improved downward diffusion of oxygen into the sediment. The associated oxidation of previously formed pyrite resulted in a lowering of pore water pH and forced dissolution of biogenic phosphate. Phosphate dissolution was followed by formation of secondary marcasite and phosphate. Repeated, episodic reworking caused repetitive cycles of phosphatic dissolution and reprecipitation, enriching MREEs in reprecipitated apatite. A generally “deeper” seated redox boundary favored P-remineralization within the sediment matrix, and multiple repeats of this process in combination with wave and current reworking at the seabed led to the formation of larger phosphatic aggregates and concentration of phosphate nodules in discrete horizons.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Sedimentary Geology - Volume 329, November 2015, Pages 40-61
Journal: Sedimentary Geology - Volume 329, November 2015, Pages 40-61
نویسندگان
Yifan Li, Juergen Schieber,