View in EDS

An ANGSA Study: Crystal Size Distributions of Ilmenite in Basalts From Apollo 17 Drive Tube 73002.

Saved in:
Bibliographic Details
Title: An ANGSA Study: Crystal Size Distributions of Ilmenite in Basalts From Apollo 17 Drive Tube 73002.
Authors: Valenciano, Jessika L.1 (AUTHOR) jvalenc2@nd.edu, Neal, Clive R.1 (AUTHOR), Eckley, Scott A.2 (AUTHOR), Shearer, Charles K.3 (AUTHOR)
Source: Journal of Geophysical Research. Planets. Aug2025, Vol. 130 Issue 8, p1-14. 14p.
Subject Terms: *Particle size distribution, Ilmenite, Basalt, Lunar surface, Moon, Computed tomography, Thermal properties
Company/Entity: Apollo program (U.S.)
Abstract: Double drive tubes 73002 (upper) and 73001 (lower) were collected during Apollo 17 from a landslide deposit at the base of the South Massif in the Taurus‐Littrow valley. The drive tubes were opened for the first time as part of the Apollo Next Generation Sample Analysis (ANGSA) project, representing "new" samples from the Moon. Many lithic fragments (>1 mm in size) were extracted from the core during core dissection and preliminary examination (PE), including high‐Ti mare basalt clasts. Those >4 mm fragments were three‐dimensionally imaged using X‐ray computed tomography (XCT). The crystal size distributions of ilmenite were measured in 10 high‐Ti mare basalts and within the matrix of an impact melt breccia from drive tube 73002 using thin section "slices" from the 3D XCT scans. Residence times (of the crystals in the melt from which they grew) were estimated using experimental growth rates for each sample with all but 73002,2015 being relatively short (<1 year). Linear (constant) cooling rates were determined, expanding upon data already obtained from other Apollo 17 high‐Ti basalts showing that these ANGSA basalt clasts had similar cooling histories to those previously studied. Comparison with ilmenite cooling rate experiments estimated cooling rates of <10°C/h for each clast. Plain Language Summary: High‐Ti (>6 wt% TiO2) basalts are not found on Earth and are unique to the Moon. Ten high‐Ti mare (lunar) basalt clasts found in a previously unopened double‐drive tube 73002 collected during the 1972 Apollo 17 mission to the Moon were examined. These basalt fragments were analyzed to determine their cooling histories using the mineral ilmenite (FeTiO3) for crystal size distributions, a method that uses the lengths of crystals and their population density to determine a relative cooling rate for an igneous sample. These basalts cooled at different, but constant rates and all but one of these clasts are estimated to have taken less than a year to cool completely. It is possible that these basalt clasts originate from different areas of the same flow, but compositional and age data are still needed to confirm this. X‐ray computed tomography is a powerful tool for identifying the flow orientation of constituent crystals. Key Points: Ten high‐Ti mare basalt clasts are analyzed for ilmenite crystal size distribution analysis and display a range of cooling ratesBasalt clasts potentially originate from different areas of the same flow—compositional and age data are required to confirm thisX‐ray Computed Tomography of clasts from 73002 allows for non‐destructive quantitative textural analyses [ABSTRACT FROM AUTHOR]
Copyright of Journal of Geophysical Research. Planets is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: GreenFILE
Description
Abstract:Double drive tubes 73002 (upper) and 73001 (lower) were collected during Apollo 17 from a landslide deposit at the base of the South Massif in the Taurus‐Littrow valley. The drive tubes were opened for the first time as part of the Apollo Next Generation Sample Analysis (ANGSA) project, representing "new" samples from the Moon. Many lithic fragments (>1 mm in size) were extracted from the core during core dissection and preliminary examination (PE), including high‐Ti mare basalt clasts. Those >4 mm fragments were three‐dimensionally imaged using X‐ray computed tomography (XCT). The crystal size distributions of ilmenite were measured in 10 high‐Ti mare basalts and within the matrix of an impact melt breccia from drive tube 73002 using thin section "slices" from the 3D XCT scans. Residence times (of the crystals in the melt from which they grew) were estimated using experimental growth rates for each sample with all but 73002,2015 being relatively short (<1 year). Linear (constant) cooling rates were determined, expanding upon data already obtained from other Apollo 17 high‐Ti basalts showing that these ANGSA basalt clasts had similar cooling histories to those previously studied. Comparison with ilmenite cooling rate experiments estimated cooling rates of <10°C/h for each clast. Plain Language Summary: High‐Ti (>6 wt% TiO2) basalts are not found on Earth and are unique to the Moon. Ten high‐Ti mare (lunar) basalt clasts found in a previously unopened double‐drive tube 73002 collected during the 1972 Apollo 17 mission to the Moon were examined. These basalt fragments were analyzed to determine their cooling histories using the mineral ilmenite (FeTiO3) for crystal size distributions, a method that uses the lengths of crystals and their population density to determine a relative cooling rate for an igneous sample. These basalts cooled at different, but constant rates and all but one of these clasts are estimated to have taken less than a year to cool completely. It is possible that these basalt clasts originate from different areas of the same flow, but compositional and age data are still needed to confirm this. X‐ray computed tomography is a powerful tool for identifying the flow orientation of constituent crystals. Key Points: Ten high‐Ti mare basalt clasts are analyzed for ilmenite crystal size distribution analysis and display a range of cooling ratesBasalt clasts potentially originate from different areas of the same flow—compositional and age data are required to confirm thisX‐ray Computed Tomography of clasts from 73002 allows for non‐destructive quantitative textural analyses [ABSTRACT FROM AUTHOR]
ISSN:21699097
DOI:10.1029/2024JE008580