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Phosphate-rich sedimentary rocks: significance for organic facies and petroleum exploration

Journal Article:

Abstract

Phosphorus-bearing rocks and sediments can be divided into two genetically distinct classes: phosphatic shales or limestones and phosphorites. Phosphatic shales are primary sediments in which phosphate nodules or micronodules have formed diagenetically by precipitation of calcium phosphates derived mainly from organic phosphorus. The nodules form in reducing environments at shallow depths within the sediments, where loss of phosphate by diffusion to the overlying water column is minimized. Highly biogenic sediments containing large amounts of organic matter and some fine clastic debris provide ideal environments for the formation of phosphate nodules. Phosphorites, in contrast, represent concentrated accumulations of reworked phosphate nodules which originated in phosphatic shales or limestones. Currents, wave action, recrystallization, and erosion and resedimentation are important mechanisms in the concentration process. Phosphatic shales and limestones may become excellent oil source rocks if thermal maturity is achieved. They are useful facies indicators for anoxic or nearly anoxic depositional environments, and are often associated with restricted basins, or, during certain geologic periods, with broad shelves developed during transgressions. Phosphorites, in contrast, are often correlated with sea-level regressions or uplifts. They are modest source rocks because of their low organic carbon contents and the fact that they were reworked under oxidizing conditions.  More>>
Authors:
Publication Date:
Mar 01, 1982
Product Type:
Journal Article
Reference Number:
EDB-82-087443
Resource Relation:
Journal Name: J. Geochem. Explor.; (Netherlands); Journal Volume: 16:2
Subject:
02 PETROLEUM; 58 GEOSCIENCES; PETROLEUM DEPOSITS; EXPLORATION; PHOSPHATE ROCKS; RESOURCE POTENTIAL; CARBONACEOUS MATERIALS; CLASSIFICATION; LIMESTONE; SEDIMENTARY BASINS; SHALES; SOURCE ROCKS; CARBONATE ROCKS; GEOLOGIC DEPOSITS; GEOLOGIC STRUCTURES; MATERIALS; MINERAL RESOURCES; RESOURCES; ROCKS; SEDIMENTARY ROCKS; 020200* - Petroleum- Reserves, Geology, & Exploration; 580300 - Mineralogy, Petrology, & Rock Mechanics- (-1989)
OSTI ID:
5667269
Research Organizations:
Mobil Research and Development Corp., Dallas, TX
Country of Origin:
Netherlands
Language:
English
Other Identifying Numbers:
Journal ID: CODEN: JGCEA
Submitting Site:
HEDB
Size:
Pages: 135-160
Announcement Date:

Journal Article:

Citation Formats

Waples, D W. Phosphate-rich sedimentary rocks: significance for organic facies and petroleum exploration. Netherlands: N. p., 1982. Web.
Waples, D W. Phosphate-rich sedimentary rocks: significance for organic facies and petroleum exploration. Netherlands.
Waples, D W. 1982. "Phosphate-rich sedimentary rocks: significance for organic facies and petroleum exploration." Netherlands.
@misc{etde_5667269,
title = {Phosphate-rich sedimentary rocks: significance for organic facies and petroleum exploration}
author = {Waples, D W}
abstractNote = {Phosphorus-bearing rocks and sediments can be divided into two genetically distinct classes: phosphatic shales or limestones and phosphorites. Phosphatic shales are primary sediments in which phosphate nodules or micronodules have formed diagenetically by precipitation of calcium phosphates derived mainly from organic phosphorus. The nodules form in reducing environments at shallow depths within the sediments, where loss of phosphate by diffusion to the overlying water column is minimized. Highly biogenic sediments containing large amounts of organic matter and some fine clastic debris provide ideal environments for the formation of phosphate nodules. Phosphorites, in contrast, represent concentrated accumulations of reworked phosphate nodules which originated in phosphatic shales or limestones. Currents, wave action, recrystallization, and erosion and resedimentation are important mechanisms in the concentration process. Phosphatic shales and limestones may become excellent oil source rocks if thermal maturity is achieved. They are useful facies indicators for anoxic or nearly anoxic depositional environments, and are often associated with restricted basins, or, during certain geologic periods, with broad shelves developed during transgressions. Phosphorites, in contrast, are often correlated with sea-level regressions or uplifts. They are modest source rocks because of their low organic carbon contents and the fact that they were reworked under oxidizing conditions. Nevertheless, because phosphorites are derived from, and often grade into, phosphatic shales, they also are of potential utility in the search for oil source beds.}
journal = {J. Geochem. Explor.; (Netherlands)}
volume = {16:2}
journal type = {AC}
place = {Netherlands}
year = {1982}
month = {Mar}
}