The Karoo Province of Southern Africa; origin of trace element enrichment patterns

Saved in:
Authors:Cox, K. G.
Author Affiliations:Primary:
Dep. Geol. Mineral., Oxford OX1 3PR, United Kingdom
Volume Title:Continental basalts and mantle xenoliths; papers prepared for a UK Volcanic Studies Group meeting at the University of Leicester
Volume Authors:Hawkesworth, C. J.; Norry, M. J.
Source:p.139-157; UK Volcanic Studies Group meeting; Continental basalts and mantle xenoliths, Leicester, United Kingdom, Jan. 1983, C. J. Hawkesworth and M. J. Norry. Publisher: Shiva Publ., Nantwich, United Kingdom. ISBN: 0-906812-34-8
Publication Date:1983
Note:In English; illus. incl. 10 anal., 3 tables, sketch map, geol. sketch map
Summary:Enrichment patterns involving K, Rb, Ba, Sr, Zr, Nb, P, Ti and Y are presented for Karoo lavas relative to MORB. The most enriched types (picrite basalts from SE Zimbabwe and N Lebombo) are enriched by a factor of 80 in Ba, 10-40 for Sr, Rb and K, and factors of approx 5-6 in Zr, Nb and P; Ti is only enriched by a factor of 2 and Y by = or <1.5. In contrast, the least enriched rocks (basaltic lavas and dykes) are enriched in K, Rb and Ba by factors of only 5-10. This great range cannot be explained by varying degrees of fractionation en route to the surface; nor is crustal contamination a major factor in generating the observed patterns. Detailed studies of the picrite basalts indicate that two end-member primitive magmas are required; these may be identified as basalt-depleted/trace-element-enriched and basalt-less-depleted/-trace-element-less-enriched. Thus it is suggested that trace-element heterogeneity in the mantle is the principal controlling factor in determining trace-element levels in the lavas. [R.A.H.]
Subjects:Basalts; Crust; Enrichment; Geochemistry; Igneous rocks; Isotopes; Karoo Supergroup; Magmas; Major elements; Mantle; Partial melting; Partitioning; Petrology; Plutonic rocks; Pollution; Trace elements; Ultramafics; Volcanic rocks; Africa; South Africa; Southern Africa
Abstract Numbers:84M/1706
Record ID:1986079636
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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