Rare earth elements as indicators of different marine depositional environments in chert and shale

Journal Article · Thu Mar 01 04:00:00 EST 1990 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1990)018<0268:REEAIO>2.3.CO;2· OSTI ID:6314596

Murray, R W; Jones, D L ^[1]; Bruchholtz ten Brink, M R; Gerlach, D C; Russ, III, G P ^[2]

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1. Univ. of California, Berkeley (USA)
2. Lawrence Livermore National Laboratory, CA (USA)

Differences in rare earth element (REE) relative fractionations and total abundances in marine cherts and shales reflect the depositional location of the sediments. Based on cerium anomaly (Ce/Ce{asterisk}) and total REE abundance ({Sigma}REE) variations preserved in interbedded chert and shale sequences of the Franciscan assemblage, the Claremont Formation, and the Monterey Formation of coastal California, we can resolve three depositional regimes: spreading ridge proximal, ocean-basin floor, and continental margin. This resolution of depositional environment, previously unattainable in otherwise physically indistinct marine sedimentary rocks, provides a potentially powerful new tool for tectonic and stratigraphic reconstructions. Chert and shale deposited near the spreading ridge (within {approximately} 400 km) under the influence of metalliferous activity are characterized by extremely low Ce anomalies (Ce/Ce{asterisk} {approximately} 0.29), those from an ocean-basin floor setting by well-developed yet less extreme Ce anomalies (Ce/Ce{asterisk} {approximately} 0.55), and those from continental margin regimes by no or slight anomalies (Ce/Ce{asterisk} {approximately} 0.90 to 1.30). {Sigma}REE in chert and shale are extremely low in regimes greatly influenced by continental input, owing to the high sedimentation rats, which minimizes exposure time to seawater and, thus, the adsorption of REE. Preliminary results indicate that the effect of diagenesis does not mask the primary REE depositional signature.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6314596
• Journal Information: Geology; (USA), Journal Name: Geology; (USA) Vol. 18:3; ISSN GLGYB; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ABUNDANCE
ADSORPTION
CALIFORNIA
CERIUM
CHEMISTRY
CHERT
COASTAL REGIONS
CONTINENTAL MARGIN
CORRELATIONS
DEPOSITION
DIAGENESIS
EARTH CRUST
ELEMENTS
FEDERAL REGION IX
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGY
HYDROGEN COMPOUNDS
MEASURING METHODS
METALS
NORTH AMERICA
OCEANIC CRUST
OXYGEN COMPOUNDS
RARE EARTHS
ROCKS
SEA-FLOOR SPREADING
SEAWATER
SEDIMENTARY ROCKS
SEDIMENTATION
SHALES
SORPTION
STRATIGRAPHY
TECTONICS
USA
VARIATIONS
WATER