Abstract
Recently groundmass samples of two high-K volcanic rocks (MDO- 31A, 36-I) and a low-K basalt (BB- 6) have been proposed for Quaternary KAr standardization. The ages given by the suppliers are ∼ 250 ka (MDO- 31A), 4 ka ( 36-I) and 450 ka (BB- 6). Sample 36-I could be used as zero-age sample for many purposes. 40 Ar 39 Ar incremental heating measurements reveal no severe distortions for the KAr systematics of the groundmass samples. Therefore they should be suitable for Quaternary KAr age standardization. The BB- 6 basalt standard shows a slightly distorted 40 Ar 39 Ar age spectrum and obviously contains mineral phases with excess 40Ar. These properties restrict the suitability of BB- 6 for KAr standardization to a certain degree. The geochemical biotite standard Mica-Fe showing both varying K and 40Ar concentrations and disturbed 40 Ar 39 Ar patterns should not be used as reference material in KAr chronometry. First K and Ar results on a recently prepared Tertiary biotite (HD-B 1) are presented. Four kg of this pure biotite ( t=25 Ma, K=8.0%, 40Ar ★=7.7 nl g −1 (STP) = 86% of total 40Ar) are provided for distribution to interested laboratories.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
