Other
Scientific paper
Dec 1992
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992e%26psl.114..193s&link_type=abstract
Earth and Planetary Science Letters, Volume 114, Issue 1, p. 193-209.
Other
30
Scientific paper
Phanerozoic alkali basalts from Israel, which have erupted over the past 200 Ma, have isotopic compositions similar to PREMA (``prevalent mantle'') with narrow ranges of initial ɛNd(T) = +3.9-+5.9 87Sr/86Sr(T) = 0.70292-0.70334 206Pb/204Pb(T) = 18.88-19.99 207Pb/204Pb(T) = 15.58-15.70 and 208Pb/204Pb(T) = 38.42-39.57. Their Nb/U (43 +/- 9) and Ce/Pb (26 +/- 6) ratios are identical to those of normal oceanic basalts, demonstrating that the basalts are essentially free of crustal contamination. Overall, the basalts are chemically and isotopically indistinguishable from many ordinary plume basalts, but no plume track can be identified.
We propose that these and other, similar, magmas from the Arabian plate originated from a ``fossilized'' head of a mantle plume, which was unable to penetrate the continental lithosphere and was therefore trapped and stored beneath it. The plume head was emplaced some time between the late Proterozoic crust formation and the initiation of the Phanerozoic magmatic cycles. Basalts from rift environments in other continental localities show similar geochemistry to that of the Arabian basalts and their sources may also represent fossil plume heads trapped below the continents. We suggest that plume heads are, in general, characterized by the PREMA isotopic mantle signature, because the original plume sources (which may have HIMU or EM-type composition) have been diluted by overlying mantle material, which has been entrained by the plume heads during ascent.
On the Arabian plate, rifting and thinning of the lithosphere caused partial melting of the stored plume, which led to periodic volcanism. In the late Cenozoic, the lithosphere broke up and the Red Sea opened. N-MORB tholeiites are now erupting in the central trough of the Red Sea, where the lithosphere has moved apart and the fossil plume has been exhausted, whereas E-MORBs are erupting in the northern and southern troughs, still tapping the plume reservoir. Fossil plumes, which are temporarily trapped at the base of the lithosphere, may explain why the uppermost mantle normally appears enriched when it is sampled by continental rift zones but depleted when it is sampled by MORB.
Hofmann Albrecht W.
Stein Mordechai
No associations
LandOfFree
Fossil plume head beneath the Arabian lithosphere? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Fossil plume head beneath the Arabian lithosphere?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fossil plume head beneath the Arabian lithosphere? will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1114308