Phosphogenesis and weathering of shelf sediments from the southeastern United States: Implications for Miocene. delta. sup 13 C excursions and global cooling

Journal Article · Sat Dec 01 00:00:00 EST 1990 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1990)018<1227:PAWOSS>2.3.CO;2· OSTI ID:5798445

Compton, J S ^[1]; Snyder, S W ^[2]; Hodell, D A ^[3]

---

1. Univ. of South Florida, St. Petersburg (USA)
2. North Carolina State Univ., Raleigh (USA)
3. Univ. of Florida, Gainesville (USA)

The enormous phosphorite deposits of the southeastern United States indicate intense upwelling but contain small amounts of organic carbon. The authors propose that deposition of organic-rich sediment on continental shelves in the southeastern United States and elsewhere during marine transgressions in the late Oligocene and early to middle Miocene resulted in global positive {delta}{sup 13}C shifts and the formation of early diagenetic phosphorite. Multiple reworking and supergene weathering from subaerial exposure during Miocene marine regressions oxidized most of the organic carbon and resulted in the return of {delta}{sup 13}C to its preexcursion value. The estimated phosphorite content of the southeastern United States requires sufficient organic carbon burial (>10{sup 15} kg carbon) to support a 1{per thousand} {delta}{sup 13}C excursions, sea-level fluctuations, organic carbon burial, phosphogenic episodes, and possibly global cooling during the Cenozoic.

• OSTI ID: 5798445
• Journal Information: Geology; (USA), Vol. 18:12; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONTINENTAL SHELF
WEATHERING
FEDERAL REGION V
PHOSPHORITES
ORIGIN
CARBON 13
CARBON CYCLE
CLIMATES
COOLING
CORRELATIONS
DEPOSITION
ECOLOGICAL CONCENTRATION
GLOBAL ASPECTS
ISOTOPE RATIO
MIOCENE EPOCH
ORGANIC MATTER
OXIDATION
SEA LEVEL
SEDIMENTS
VARIATIONS
CARBON ISOTOPES
CENOZOIC ERA
CHEMICAL REACTIONS
CONTINENTAL MARGIN
EVEN-ODD NUCLEI
GEOLOGIC AGES
ISOTOPES
LEVELS
LIGHT NUCLEI
NORTH AMERICA
NUCLEI
PHOSPHATE ROCKS
ROCKS
SEDIMENTARY ROCKS
STABLE ISOTOPES
TERTIARY PERIOD
USA
580000* - Geosciences