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A common mantle plume source beneath the entire East African Rift System revealed by coupled helium‐neon systematics
Author(s) -
Halldórsson Sæmundur A.,
Hilton David R.,
Scarsi Paolo,
Abebe Tsegaye,
Hopp Jens
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl059424
Subject(s) - geology , east african rift , mantle (geology) , rift , plume , mantle plume , volcano , magmatism , geochemistry , neon , hotspot (geology) , xenolith , asthenosphere , lithosphere , geophysics , seismology , tectonics , physics , atomic physics , argon , thermodynamics
We report combined He‐Ne‐Ar isotope data of mantle‐derived xenoliths and/or lavas from all segments of the East Africa Rift System (EARS). Plume‐like helium isotope ( 3 He/ 4 He) ratios (i.e., greater than the depleted MORB mantle (DMM) range of 8 ± 1R A ) are restricted to the Ethiopia Rift and Rungwe, the southernmost volcanic province of the Western Rift. In contrast, neon isotope trends reveal the presence of an ubiquitous solar (plume‐like) Ne component throughout the EARS, with ( 21 Ne/ 22 Ne) EX values (where ( 21 Ne/ 22 Ne) EX is the air‐corrected 21 Ne/ 22 Ne ratio extrapolated to Ne‐B) as low as 0.034, close to that of solar Ne‐B (0.031). Coupling ( 21 Ne/ 22 Ne) EX with 4 He/ 3 He ratios indicates that all samples can be explained by admixture between a single mantle plume source, common to the entire rift, and either a DMM or subcontinental lithospheric mantle source. Additionally, we show that the entire sample suite is characterized by low 3 He/ 22 Ne S ratios (mostly < 0.2)—a feature characteristic of oceanic hot spots such as Iceland. We propose that the origin of these unique noble gas signatures is the deeply rooted African Superplume which influences magmatism throughout eastern Africa. We argue that the Ethiopia and Kenya domes represent two different heads of this common mantle plume source.