Journal
LITHOS
Volume 97, Issue 3-4, Pages 307-322Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.lithos.2007.01.001
Keywords
nephrite; jade; greenstone; pounamu; Rb-Sr dating; strontium isotopes
Categories
Ask authors/readers for more resources
Nephrite jade occurs in three terranes (Dun Mountain-Maitai, Caples and Torlesse) in New Zealand, where it is associated with ultramafic and ophiolitic rocks in narrow metasomatic reaction zones at the margins of serpentinite (having harzburgite/gabbro/ dolerite precursors) with silicic metasediments and metavolcanics. True nephrite fabrics are developed only locally where marginal shearing is intense, and late in the metamorphic history. Sr-87/Sr-86 values of these nephrites do not display the primitive values of their gabbro/dolerite precursor component i.e. 0.7030-0.7035, as expected if formed during serpentinisation. Rather, the nephrites have more evolved Sr-87/Sr-86 values inherited from the metasediment component at a later stage, and which fall within particular terrane groups: Dun Mountain-Maitai 0.7045-0.7060, Caples 0.7058-0.7075 and Torlesse 0.7085-0.7110. Rb-Sr ages and initial Sr-87/Sr-86 ratios of the metasediment component from in situ nephrite localities, when compared with their counterparts throughout the host terrane, show that nephrite Sr isotopic compositions are characteristic of the host terrane. (c) 2007 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available