Carbon and oxygen isotope geochemistry of chlorite-zone rocks of the Waterville limestone, Maine, USA

Journal Article · · American Mineralogist; (United States)

OSTI ID:5528788

Rumble, D III; Hoering, T C ^[1]; Oliver, N H.S. ^[2]; Ferry, J M ^[3]

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1. Geophysical Lab., Washington, D.C. (United States)
2. Monash Univ., Clayton, Victoria (Australia)
3. Johns Hopkins Univ., Baltimore, MD (United States)

Analyses of 266 samples of calcite and dolomite from veins and wall rocks of the Waterville limestone from the chlorite zone have been made for {delta}{sup 18}O and {delta}{sup 13}C. The least altered samples of limestone have {delta}{sup 18}O values of +19.5 to +20.5{per thousand} (SMOW) and {delta}{sup 13}C is {minus}1 to +1{per thousand} (PDB). The isotope values have been shifted by 3 to 7{per thousand} in {delta}{sup 18}O and 0 to 4{per thousand} in {delta}{sup 13}C relative to unaltered marine limestones of equivalent stratigraphic age. The shifts are similar to isotopic changes observed in unmetamorphosed but diagenetically altered limestones. The shifts are also consistent with the infiltration of H{sub 2}O-rich fluids during metamorphism. The authors cannot make a definite choice, at the present time, between the two explanations of changes in isotopic compositions, diagenetic or metamorphic. The limestone in the chlorite zone is crosscut by four generations of veins and two sets of solution cleavages. Two older generations of veins and one of solution cleavage preceded metamorphism. The growth of metamorphic minerals was accompanied by solution of calcite along solution cleavage and its precipitation in synmetamorphic veins. During a postmetamorphic episode of vein formation, isotope alteration halos with depletions of 1-2{per thousand} in {delta}{sup 18}O and of 4{per thousand} in {delta}{sup 13}C were imposed on wall rocks. The Waterville limestone therefore has had a protracted history of fluid infiltration, involving both pervasive and fracture flow, that was not limited just to the peak of regional metamorphism.

• OSTI ID: 5528788
• Journal Information: American Mineralogist; (United States), Vol. 76:5-6; ISSN 0003-004X
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GEOLOGIC DEPOSITS
GEOCHEMISTRY
MAINE
CALCITE
CARBON 13
CHLORITE MINERALS
DIAGENESIS
DISSOLUTION
DOLOMITE
GEOLOGIC HISTORY
ISOTOPE RATIO
LIMESTONE
METAMORPHISM
OXYGEN 18
PRECIPITATION
RESERVOIR FLUIDS
CARBON ISOTOPES
CARBONATE MINERALS
CARBONATE ROCKS
CHEMISTRY
DEVELOPED COUNTRIES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FLUIDS
ISOTOPES
LIGHT NUCLEI
MINERALS
NORTH AMERICA
NUCLEI
OXYGEN ISOTOPES
ROCKS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
SILICATE MINERALS
STABLE ISOTOPES
USA
580000* - Geosciences