Trace element of Sr and Nd isotopic composition of mantle xenoliths from the Big Pine volcanic field, California

Saved in:
Online Access: Get full text
doi: 10.1029/94JB02883
Authors:Beard, Brian L.; Glazner, Allen F.
Author Affiliations:Primary:
University of North Carolina, Department of Geology, Chapel Hill, NC, United States
Volume Title:Journal of Geophysical Research
Source:Journal of Geophysical Research, 100(B3), p.4169-4179. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148-0227
Publication Date:1995
Note:In English. 43 refs.; illus., incl. 1 plate, 5 tables, geol. sketch map
Summary:Mantle xenoliths from the Quaternary Big Pine volcanic field of eastern California provide direct evidence for the presence of isotopically enriched mantle beneath the Sierran Province of the western United States. Sr and Nd isotopic compositions determined on five bulk rock and five clinopyroxene separates are negatively correlated; εNd values range from +13.8 to -3.4, and 87Sr/86Sr ratios range from 0.7022 to 0.7065. The measured Sr and Nd contents and Ce/Yb ratios of mantle xenoliths in the Big Pine volcanic field are well correlated with Sr and Nd isotopic compositions, and these xenoliths define an 820-m.y.-old Sm-Nd isochron. The Big Pine mantle xenoliths have similar textures and mineral compositions, and we interpret the large range in isotopic and trace element compositions to be a result of cryptic mantle metasomatism. The timing of this mantle metasomatic event is unclear but a maximum Late Proterozoic age can be inferred from the 820 Ma Sm-Nd isochron. If the Sm-Nd isochron is interpreted as a result of recent metasomatism then the metasomatising agent was similar in composition to the Big Pine basalts. If the isochron is interpreted to have age significance then this mantle metasomatism was associated with late Proterozoic rifting of the western margin of North America. Although production of isotopically enriched mantle is generally attributed to ancient subduction, these data are inconsistent with such an interpretation. Copyright 1995 by the American Geophysical Union.
Subjects:Alkaline earth metals; Basalts; Chemical composition; Genesis; Igneous rocks; Inclusions; Isotope ratios; Isotopes; Mantle; Metals; Metasomatism; Models; Neodymium; Rare earths; Rifting; Sr-87/Sr-86; Stable isotopes; Strontium; Trace elements; Volcanic rocks; Xenoliths; California; Owens Valley; United States; Big Pine volcanic field; Eastern California
Abstract Numbers:95M/4484
Record ID:1995052980
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
Tags: Add Tag
No Tags, Be the first to tag this record!
Be the first to leave a comment!
You must be logged in first