Record Details

Record 1 of 1
K-Ca Dating of Alkali-Rich Fragments in the Y-74442 and Bhola LL-Chondritic Breccias
NTRS Full-Text: Click to View  [PDF Size: 244 KB]
Author and Affiliation:
Yokoyama, T(Graduate Univ. for Advanced Studies (SOKENDAI), Tachikawa, Japan);
Misawa, K.(Graduate Univ. for Advanced Studies (SOKENDAI), Tachikawa, Japan);
Okano, O(Okayama Univ., Japan);
Shih, C. -Y.(Jacobs Technologies Engineering Science Contract Group, Houston, TX, United States);
Nyquist, L. E.(NASA Johnson Space Center, Houston, TX, United States);
Simon, J. I.(NASA Johnson Space Center, Houston, TX, United States);
Tappa, M. J.(Jacobs Technologies Engineering Science Contract Group, Houston, TX, United States);
Yoneda, S.(National Museum Natural and Science, Tukuba, Japan)
Abstract: Alkali-rich igneous fragments in the brecciated LL-chondrites, Krahenberg (LL5) [1], Bhola (LL3-6) [2], Siena (LL5) [3] and Yamato (Y)-74442 (LL4) [4-6], show characteristic fractionation patterns of alkali and alkaline elements [7]. The alkali-rich fragments in Krahenberg, Bhola and Y-74442 are very similar in mineralogy and petrography, suggesting that they could have come from related precursor materials [6]. Recently we reported Rb-Sr isotopic systematics of alkali-rich igneous rock fragments in Y-74442: nine fragments from Y-74442 yield the Rb-Sr age of 4429 plus or minus 54 Ma (2 sigma) for lambda(Rb-87) = 0.01402 Ga(exp -1) [8] with the initial ratio of Sr-87/Sr-86 = 0.7144 plus or minus 0.0094 (2 sigma) [9]. The Rb-Sr age of the alkali-rich fragments of Y-74442 is younger than the primary Rb-Sr age of 4541 plus or minus 14 Ma for LL-chondrite whole-rock samples [10], implying that they formed after accumulation of LL-chondrite parental bodies, although enrichment may have happened earlier. Marshall and DePaolo [11,12] demonstrated that the K-40 - Ca-40 decay system could be an important chronometer as well as a useful radiogenic tracer for studies of terrestrial rocks. Shih et al. [13,14] and more recently Simon et al. [15] determined K-Ca ages of lunar granitic rocks, and showed the application of the K-Ca chronometer for K-rich planetary materials. Since alkali-rich fragments in the LL-chondritic breccias are highly enriched in K, we can expect enhancements of radiogenic Ca-40. Here, we report preliminary results of K-Ca isotopic systematics of alkali-rich fragments in the LL-chondritic breccias, Y-74442 and Bhola.
Publication Date: Mar 18, 2013
Document ID:
20130009992
(Acquired Feb 25, 2013)
Subject Category: LUNAR AND PLANETARY SCIENCE AND EXPLORATION
Report/Patent Number: JSC-CN-27972
Document Type: Conference Paper
Meeting Information: 44th Lunar and Planetary Science Conference; 18 - 22 Mar. 2013; The Woodlands, TX; United States
Meeting Sponsor: Lunar and Planetary Inst.; Houston, TX, United States
Universities Space Research Association; Houston, TX, United States
Financial Sponsor: NASA Johnson Space Center; Houston, TX, United States
Organization Source: NASA Johnson Space Center; Houston, TX, United States
Description: 2p; In English; Original contains color illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: ABUNDANCE; ALKALIES; BRECCIA; CALCIUM ISOTOPES; CHONDRITES; FRAGMENTS; GEOCHRONOLOGY; IGNEOUS ROCKS; ISOTOPE RATIOS; POTASSIUM ISOTOPES; RADIOGENIC MATERIALS; RUBIDIUM ISOTOPES; STRONTIUM 87
› Back to Top
Facebook icon, External Link to NASA STI page on Facebook Twitter icon, External Link to NASA STI on Twitter YouTube icon, External Link to NASA STI Channel on YouTube RSS icon, External Link to New NASA STI RSS Feed
Find Similar Records
 
NASA Logo, External Link

NASA Official: Gerald Steeman
Sponsored By: NASA Scientific and Technical Information Program
Site Curator: STI Support Services
Last Modified: April 09, 2013

Privacy Policy & Important Notices Disclaimers, Copyright, Terms of Use Freedom of Information Act USA.gov NASA.gov NASA OCIO Free Adobe PDF Reader Free MS Word Viewer