Structure in the secular variation of seawater sup 87 Sr/ sup 86 Sr for the Ivorian/Chadian (Osagean, Lower Carboniferous)
- State Univ. of New York, Stony Brook (USA)
The secular variations of {sup 87}Sr/{sup 86}Sr in seawater for the Ivorian/Chadian, (equivalent to the Osagean, Lower Carboniferous) were determined through detailed analysis of well-preserved marine cements from the Waulsortian facies of Ireland. The results indicate that marine cements have utility in characterizing marine paleochemistries. Marine cements were judged pristine on the basis of nonluminescent character and stable isotopic composition comparable to previous estimates of Mississippian marine calcite. Analysis of the marine cements yielded {sup 87}Sr/{sup 86}Sr ratios lower than previously reported values for the Ivorian/Chadian. Error resulting from chronostratigraphic correlation between different geographic areas was avoided by restricting the sample set to a single 1,406-ft-long core (core P-1). The P-1 core is estimated to represent a minimum of 8.7 m.y. of continuous Waulsortian Limestone deposition. The {sup 87}Sr/{sup 86}Sr ratios of 11 nonluminescent cements document a non-monotonic variation in seawater {sup 87}Sr/{sup 86}Sr along the length of the core. {sup 87}Sr/{sup 86}Sr ranges from a high of 0.707908 in the early Ivorian to a low of about 0.707650 in the late Ivorian and middle Chadian with an early Chadian maximum at 0.707800 (all data are adjusted to a value of 0.710140 for SRM 987). The indicated maximum rate of change in seawater {sup 87}Sr/{sup 86}Sr is {minus}0.00011/Ma, comparable in magnitude to Tertiary values. The secular variation curve of seawater {sup 87}Sr/{sup 86}Sr for the Ivorian/Chadian has previously been thought to decrease monotonically with decreasing age. These data suggest that the seawater {sup 87}Sr/{sup 86}Sr variation over this interval may be sinusoidal in nature and emphasize the importance of well-characterized intraformational isotopic base lines.
- OSTI ID:
- 7061389
- Report Number(s):
- CONF-900605-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
Similar Records
C-O isotopic composition of Devono-Carboniferous carbonates of Belgium and Ireland: evidence of basinal anoxia and global change
Geochemistry of Cambro-Ordovician Arbuckle limestone, Oklahoma: Implications for diagenetic. delta. sup 18 O alteration and secular. delta. sup 13 C and sup 87 Sr/ sup 86 Sr variation
Related Subjects
CHAD
CARBONATE ROCKS
IVORY COAST
CALCITE
CARBONIFEROUS PERIOD
ISOTOPE RATIO
SEAWATER
STRONTIUM 86
STRONTIUM 87
TERTIARY PERIOD
AFRICA
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
BETA DECAY RADIOISOTOPES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CENOZOIC ERA
DEVELOPING COUNTRIES
ELECTRON CAPTURE RADIOISOTOPES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
HOURS LIVING RADIOISOTOPES
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MINERALS
NUCLEI
OXYGEN COMPOUNDS
PALEOZOIC ERA
RADIOISOTOPES
ROCKS
SEDIMENTARY ROCKS
STABLE ISOTOPES
STRONTIUM ISOTOPES
WATER
580000* - Geosciences