Sr isotope study of vein and cave calcites from southern Israel

Saved in:
Authors:Avigour, A.; Magaritz, M.; Issar, A.; Dodson, M. H.
Author Affiliations:Primary:
Ben Gurion Univ., Dep. Geol. and Mineral., Beer Sheva, Israel
Weizmann Inst. Sci., Israel
Jacob Blaustein Inst. Desert Res., Israel
Univ. Leeds, United Kingdom
Volume Title:Chemical Geology
Source:Chemical Geology, 82(1-2), p.69-81. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0009-2541
Publication Date:1990
Note:In English. 42 refs.; illus. incl. 1 table, sketch map
Summary:The Sr isotope compositions of secondary calcites from the Negev, southern Israel, were compared to those of the marine carbonate host rocks, which range from Triassic to Eocene, in order to understand fluid source and migration through fractures in dominantly carbonate strata. The Sr isotopes of these calcite clusters are divided into two groups: 1) calcites with 87 Sr/ 86 Sr values greater than those of the host carbonates; and 2) calcites with 87 Sr/ 86 Sr values close to those of the host carbonate. These secondary calcites were found on the main tectonic lines of the Negev (faults and fold axes) and are enriched in Sr relative to the marine carbonate country rocks. These calcites are associated with, or crossed by, thin veins filled by Fe- and Mn-oxides. Secondary calcites with 87 Sr/ 86 Sr values close to those of the marine country rocks are found in karstic caves and veins, and are located in sites which are not on the major faults and fold axes. These calcites are not crossed by Fe- and Mn-oxides. The isotopic results indicate that the solutions from which the secondary minerals of the first group precipitated were not in isotopic equilibrium with the marine host rocks. Possible sources of the precipitating solutions can be surface rain descending through the fault system or ascending groundwaters from the Nubian aquifer (Palaeozoic to early Cretaceous). In both cases there would be a limited interaction with the host sandstone rock which usually is depleted in Sr. The similarity of the 87 Sr/ 86 Sr values to those of the host rocks in the second group suggests that the main source of Sr in these calcite crystals was from the dissolution of the marine carbonate country rocks by rain- and flood-waters. [P.Br.]
Subjects:Alkaline earth metals; Aquifers; Calcite; Carbonates; Caves; Geochemistry; Ground water; Isotopes; Metals; Minerals; Precipitation; Secondary minerals; Sr-87/Sr-86; Stable isotopes; Strontium; Veins; Asia; Israel; Middle East; Negev
Abstract Numbers:90M/4328
Record ID:1990048321
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
Tags: Add Tag
No Tags, Be the first to tag this record!
Be the first to leave a comment!
You must be logged in first