Enhanced mantle conductivity from sulfide minerals, southern Sierra Nevada, California

Citation
Mn. Ducea et Sk. Park, Enhanced mantle conductivity from sulfide minerals, southern Sierra Nevada, California, GEOPHYS R L, 27(16), 2000, pp. 2405-2408
Citations number
18
Categorie Soggetti
Earth Sciences
Journal title
GEOPHYSICAL RESEARCH LETTERS
ISSN journal
00948276 → ACNP
Volume
27
Issue
16
Year of publication
2000
Pages
2405 - 2408
Database
ISI
SICI code
0094-8276(20000815)27:16<2405:EMCFSM>2.0.ZU;2-2
Abstract
Petrographic studies of peridotitic xenoliths entrained in late Quaternary basalts from beneath the southern Sierra Nevada have revealed the presence of accessory sulfide minerals along grain boundaries and fractures. Equilib ration temperatures from the xenoliths are sufficiently high that the molte n sulfides coexist with the basaltic melt. Sulfides are extremely conductiv e relative to the solid matrix or the basaltic melt, so a small fraction ca n increase the bulk conductivity of the mantle appreciably. Previous estima tes of 2-5% partial melt from magnetotelluric measurements can be plausibly reduced to less than 1%. Such low melt percentages have longer residence t imes in the mantle and are more consistent with the volumetrically minor la te Quaternary basalt flows and the primitive basalt compositions.