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Two Slowly Cooled and Chemically Diverse Basalt Clasts Identified in ANGSA Core 73001.

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Title: Two Slowly Cooled and Chemically Diverse Basalt Clasts Identified in ANGSA Core 73001.
Authors: Wilbur, Z. E.1,2 (AUTHOR) wilburz@si.edu, Tatsch, A. N.1 (AUTHOR), Barnes, J. J.1 (AUTHOR), Stadermann, A. C.3,4 (AUTHOR), Eckley, S. A.5 (AUTHOR), Erickson, T. M.5 (AUTHOR), Gross, J.3 (AUTHOR), Shearer, C. K.6 (AUTHOR), Zeigler, R. A.3 (AUTHOR), McCubbin, F. M.3 (AUTHOR)
Source: Journal of Geophysical Research. Planets. Sep2025, Vol. 130 Issue 9, p1-21. 21p.
Subject Terms: Basalt, Cooling, Lunar surface, Lava flows, Lunar exploration
Company/Entity: Apollo program (U.S.)
Abstract: The Apollo 17 mission returned a double drive tube, 73001/73002, which was opened after ∼50 years and made available to the community through the Apollo Next Generation Sample Analysis (ANGSA) program. Here, we investigate the petrogenesis of two basalt clasts separated from the 73001 core, samples 73001,1095B and 73001,1234B. During the preliminary examination by NASA Curation using X‐ray computed tomography, these clasts were categorized as high‐Ti and low‐Ti basalt clasts, respectively. Our subsequent investigation confirms a high‐Ti affinity for 73001,1095B, but very low‐Ti (VLT) affinity for 73001,1234B. We compare 73001,1095B to other high‐Ti samples and show that the basalt represents a Type1B basalt. Based on the sample's low vesicularity in 3D, coarse‐grained mineralogy in 2D and 3D, and complex exsolution features, this high‐Ti basalt likely cooled slowly in the thermally insulated core of a lava flow. As VLT basalts are rare or undersampled in the lunar sample collection, the investigation of 73001,1234B with 3D techniques represents the first of its kind and offers an opportunity to more robustly understand the volcanic histories of VLT lavas. We observed low vesicularity in 3D, coarse‐grained mineralogy, and coarse pyroxene exsolution in the VLT basalt in agreement with previous studies suggesting that VLT basalts likely represent samples from the slowest cooled lava flows on the lunar surface, or from a shallow intrusive body. We show from the combination of 2D and 3D studies applied to small returned samples lacking geologic context that a comprehensive interpretation of their crystallization histories can be obtained. Plain Language Summary: The Apollo Next Generation Sample Analysis (ANGSA) program offers researchers the opportunity to study samples collected from the Moon during the Apollo 17 mission that have been specially curated, preserved, and unstudied for 50 years. We studied two volcanic rock fragments from a newly opened core sample. These rocks represent two different types of lava that crystallized on the Moon: one high in Ti, and one very low in Ti (VLT). We combine traditional 2D methods with novel 3D techniques to classify these samples and demonstrate that these rocks cooled slowly on the Moon in their respective lava flows. The high‐Ti sample is similar to other high‐Ti basalts in the Apollo 17 sample collection. The VLT basalt differs from other VLT clasts in the Apollo, Luna, and meteorite collections and offers insight into slowly crystallized volcanic materials from the Moon. Key Points: We provide mineralogy, petrology, microstructural, and 3D morphology measurements of two lunar basalts as part of the ANGSA programWe classify the studied clasts as a characteristic, high‐Ti, Type IB basalt and a new, very low‐Ti basaltThe basalts both experienced slow cooling histories, and VLT basalts likely represent the slowest cooled mare lava flows [ABSTRACT FROM AUTHOR]
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Abstract:The Apollo 17 mission returned a double drive tube, 73001/73002, which was opened after ∼50 years and made available to the community through the Apollo Next Generation Sample Analysis (ANGSA) program. Here, we investigate the petrogenesis of two basalt clasts separated from the 73001 core, samples 73001,1095B and 73001,1234B. During the preliminary examination by NASA Curation using X‐ray computed tomography, these clasts were categorized as high‐Ti and low‐Ti basalt clasts, respectively. Our subsequent investigation confirms a high‐Ti affinity for 73001,1095B, but very low‐Ti (VLT) affinity for 73001,1234B. We compare 73001,1095B to other high‐Ti samples and show that the basalt represents a Type1B basalt. Based on the sample's low vesicularity in 3D, coarse‐grained mineralogy in 2D and 3D, and complex exsolution features, this high‐Ti basalt likely cooled slowly in the thermally insulated core of a lava flow. As VLT basalts are rare or undersampled in the lunar sample collection, the investigation of 73001,1234B with 3D techniques represents the first of its kind and offers an opportunity to more robustly understand the volcanic histories of VLT lavas. We observed low vesicularity in 3D, coarse‐grained mineralogy, and coarse pyroxene exsolution in the VLT basalt in agreement with previous studies suggesting that VLT basalts likely represent samples from the slowest cooled lava flows on the lunar surface, or from a shallow intrusive body. We show from the combination of 2D and 3D studies applied to small returned samples lacking geologic context that a comprehensive interpretation of their crystallization histories can be obtained. Plain Language Summary: The Apollo Next Generation Sample Analysis (ANGSA) program offers researchers the opportunity to study samples collected from the Moon during the Apollo 17 mission that have been specially curated, preserved, and unstudied for 50 years. We studied two volcanic rock fragments from a newly opened core sample. These rocks represent two different types of lava that crystallized on the Moon: one high in Ti, and one very low in Ti (VLT). We combine traditional 2D methods with novel 3D techniques to classify these samples and demonstrate that these rocks cooled slowly on the Moon in their respective lava flows. The high‐Ti sample is similar to other high‐Ti basalts in the Apollo 17 sample collection. The VLT basalt differs from other VLT clasts in the Apollo, Luna, and meteorite collections and offers insight into slowly crystallized volcanic materials from the Moon. Key Points: We provide mineralogy, petrology, microstructural, and 3D morphology measurements of two lunar basalts as part of the ANGSA programWe classify the studied clasts as a characteristic, high‐Ti, Type IB basalt and a new, very low‐Ti basaltThe basalts both experienced slow cooling histories, and VLT basalts likely represent the slowest cooled mare lava flows [ABSTRACT FROM AUTHOR]
ISSN:21699097
DOI:10.1029/2025JE009113