FN Archimer Export Format
PT J
TI Tracing helium isotope compositions from mantle source to fumaroles at Oldoinyo Lengai volcano, Tanzania
BT 
AF MOLLEX, Gaelle
   FURI, Evelyn
   BURNARD, Pete
   ZIMMERMANN, Laurent
   CHAZOT, Gilles
   KAZIMOTO, Emmanuel O.
   MARTY, Bernard
   FRANCE, Lyderic
AS 1:1;2:1;3:1;4:1;5:2;6:3;7:1;8:1;
FF 1:;2:;3:;4:;5:;6:;7:;8:;
C1 Univ Lorraine, CNRS, UMR 7358, CRPG, 15 Rue Notre Dame Pauvres, F-54501 Vandoeuvre Les Nancy, France.
   Univ Brest, CNRS, UMR Domaines Ocean 6538, Inst Univ Europeen Mer, Pl Copernic, F-29280 Plouzane, France.
   Univ Dar Es Salaam, Dept Geol, POB 35052, Dar Es Salaam, Tanzania.
C2 UNIV LORRAINE, FRANCE
   UBO, FRANCE
   UNIV DAR ES SALAAM, TANZANIA
UM LGO
IF 3.618
TC 17
UR https://archimer.ifremer.fr/doc/00638/74994/75820.pdf
LA English
DT Article
DE ;Carbonatite;Neon;2007-2008 eruption;SCLM;Cognate xenoliths;Helium;Neon;Argon
AB Oldoinyo Lengai is the only volcano on Earth currently erupting natrocarbonatites, of which the source and genesis remain controversial. Cognate xenoliths and fumaroles were sampled at the summit of Oldoinyo Lengai, and deep crustal xenoliths from Oltatwa maar, in 2010 and 2014, after the 2007-2008 sub-Plinian eruption. The summit cognate xenoliths provide direct information on the isotopic composition of the mid-crustal magma chamber that was active during the 2007-2008 explosive eruption. Cognate xenolith-hosted pyroxenes from Oldoinyo Lengai have an average He-3/He-4 = 6.58 +/- 0.46 R-A, similar to values from nearby silicate volcanoes (4.95-7.30 R-A), and reflecting a sub-continental lithospheric mantle (SCLM) signature. This similarity implies that Oldoinyo Lengai carbonatites form from a similar mantle reservoir as the nearby silicate volcanoes. We identify SCLM, metasomatized by fluids/melts derived from the depleted convective mantle, as the common source of magmas in the Arusha volcanic province. Fumarole measurements highlight that fumarolic He-3/He-4 values have been relatively constant since at least 1988, indicating that dramatic changes to the crater region morphology during the 2007-2008 eruption did not affect the architecture of the hydrothermal system, which is probably connected to the crustal magma chamber(s). Moreover, the similarity between He-3/He-4 values from the mid-crustal magma chamber (6.58 +/- 0.46 R-A) and fumaroles (7.31 +/- 0.24 R-A) of Oldoinyo Lengai attests that helium is not subjected to atmospheric contamination or crustal assimilation during transport to the surface. 
PY 2018
PD MAR
SO Chemical Geology
SN 0009-2541
PU Elsevier Science Bv
VL 480
UT 000428012200008
BP 66
EP 74
DI 10.1016/j.chemgeo.2017.08.015
ID 74994
ER

EF