TY - JOUR
T1 - A common mantle plume source beneath the entire East African Rift System revealed by coupled helium-neon systematics
AU - Halldõrsson, Sæmundur A.
AU - Hilton, David R.
AU - Scarsi, Paolo
AU - Abebe, Tsegaye
AU - Hopp, Jens
PY - 2014/4/16
Y1 - 2014/4/16
N2 - 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 (3He/4He) ratios (i.e., greater than the depleted MORB mantle (DMM) range of 8-±-1RA) 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 (21Ne/ 22Ne)EX values (where (21Ne/ 22Ne)EX is the air-corrected 21Ne/ 22Ne ratio extrapolated to Ne-B) as low as 0.034, close to that of solar Ne-B (0.031). Coupling (21Ne/22Ne)EX with 4He/3He 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 3He/22NeS 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. Key Points He-Ne-Ar isotope data of xenoliths and lavas from the East Africa Rift System He-Ne systematics suggest a single mantle plume source The African Superplume influences magmatism throughout eastern Africa
AB - 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 (3He/4He) ratios (i.e., greater than the depleted MORB mantle (DMM) range of 8-±-1RA) 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 (21Ne/ 22Ne)EX values (where (21Ne/ 22Ne)EX is the air-corrected 21Ne/ 22Ne ratio extrapolated to Ne-B) as low as 0.034, close to that of solar Ne-B (0.031). Coupling (21Ne/22Ne)EX with 4He/3He 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 3He/22NeS 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. Key Points He-Ne-Ar isotope data of xenoliths and lavas from the East Africa Rift System He-Ne systematics suggest a single mantle plume source The African Superplume influences magmatism throughout eastern Africa
KW - Composition of the mantle
KW - Geochemistry
KW - Hotspots
KW - Intra-plate processes
KW - Mantle processes
UR - http://www.scopus.com/inward/record.url?scp=84897304528&partnerID=8YFLogxK
U2 - 10.1002/2014GL059424
DO - 10.1002/2014GL059424
M3 - Article
AN - SCOPUS:84897304528
SN - 0094-8276
VL - 41
SP - 2304
EP - 2311
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 7
ER -