DOI: 10.5061/dryad.dr7sqvb63
title: High-Ti melts from the Taurus-Littrow Valley (TLV). A product of volcanism or impact? An ANGSA investigation using the station 3 double drive tube 73001/73002

description: The ANGSA initiative examined an unopened Apollo 17 double drive tube that
 penetrated a “light mantle” surface feature that represents a landslide
 deposit originating from the South Massif in the Taurus Littrow Valley.
 Within this double drive tube are several lunar lithologies not identified
 in the Apollo, Luna, Chang’e 5 or lunar meteorite collections. One such
 lithology is lithic fragment 73002,27G. It consists of a fine-grained,
 high-Ti melt lithology which hosts lithic clasts and mineral fragments
 derived from a variety of high-Ti basalts. This lithology represents
 either a quickly cooled mare basalt with xenocrysts produced by thermal
 erosion of older crystalline high-Ti basalts, or a high-Ti impact melt
 with remnants of the target lithologies. Both types of lithologies are
 rare to non-existent, so this new sample has the potential to shed light
 on either the dynamical near-surface interactions between erupting magmas
 and previously erupted flows, or impact processes involving high-Ti mare
 basalt targets. Although not entirely unambiguous, numerous lines of
 evidence support an impact origin for this rock type. Based on crystal
 size distribution,  the interclast melt experienced rapid
 cooling, exceeding rates documented in most high-Ti mare basalts. Mineral
 and bulk chemistry and preferred orientations of matrix grains indicate
 that the rapidly-cooled portion of this lithology contains remnants of a
 variety of mare basalts. It seems unlikely that basalt flow would contain
 such a variety of xenoliths at its chilled surface. Although the
 interclast melt falls on an appropriate liquid-line-of-descent, its
 composition has characteristics distinct from other high-Ti basalts.
description: A variety of lithic fragments were separated from the 73001 and
 73002 cores during dissection and preliminary examination (PE). These
 curation activities were done in a nitrogen glove box at the Pristine
 Lunar Sample Laboratory Facility at the Johnson Space Center (JSC).  In
 the first two passes of each core, the core was dissected in 0.5 cm
 sampling intervals, and each segment was sieved into &lt;1 mm and
 &gt;1 mm size fractions (Fig. 3a,b). The &gt;1 mm lithic fragments
 were divided into 1-2 mm, 2-4 mm, and &gt;4 mm size fractions (Fig.
 3c). Individual &gt;4 mm lithic fragments were triple-sealed in Teflon
 bags (Fig. 3d), removed from the nitrogen glove box, and scanned by X-ray
 Computed Tomography in the X-FaCT Lab at NASA JSC with a Nikon XTH 320
 equipped with a 180 kV nano-focus transmission target source (Fig. 3e).
 See Gross et al. (2024) and Zeigler et al. (2024) (both in this special
 issue but not in the reference list) for detailed descriptions about the
 PE and XCT scanning, respectively, of 73001 and 73002. The sample
 identified by XCT imaging and considered in this study was lithic fragment
 27G (Fig. 3f). Lithic fragment 27G was recovered from the 1.5-2.0 cm depth
 interval from the top of drive tube 73002. Its initial sample mass was
 0.035g. An XCT video of this lithic fragment is available (presented in
 supporting information). The XCT data of 27G were used to guide the
 preparation of a thick section (73002,480) at Johnson Space Center that
 specifically exposed the two largest high-Ti clasts. Mineral data
 collected by SEM and EMPA is also available. This data was collected at
 the University of New Mexico SEM - EPMA lab.
description: # High-Ti melts from the Taurus-Littrow Valley (TLV). A product of
 volcanism or impact? An ANGSA investigation using the station 3 double
 drive tube 73001/73002
 [https://doi.org/10.5061/dryad.dr7sqvb63](https://doi.org/10.5061/dryad.dr7sqvb63) XCT Video of lithic fragment 73002,27G Mineral data are presented as an Excel file. ## Description of the data and file structure Mineral data are individual electron microprobe spot analyses of mineral grains. Lithology represents different rock units in the thin section. These units are described in the manuscript. Sample refers to the Apollo double drive tube core collected during the Apollo 17 mission at Station 3 (73002).  Mieral analyses refers to individual points on Olivine (Ol), pyroxene (Py), plagioclase (Plag), and ilmenite (Ilm). The oxide totals (SiO2, TiO2, Cr2O3.......) are presented in weight percent. For Olivine (Forsterite Fo, Fayalite Fa), Pyroxene (Enstatite En, Wollastonite Wo, Ferrosilite Fs), and Plagioclase (Albite Ab, Anorthite An, Orthoclase Or) the % of individual components are presented. ## Sharing/Access information Data was derived from the following sources: * X-ray Computed Tomography (XCT) in the X-FaCT Lab at NASA JSC with a Nikon XTH 320 equipped with a 180 kV nano-focus transmission target source * The thick section of 27G was examined, imaged, and analyzed by optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) at the University of New Mexico (UNM). Backscattered electron imaging and energy-dispersive analysis (both qualitative and quantitative) were accomplished with a TESCAN Lyra3 scanning electron microscope equipped with an IXRF silicon-drift energy-dispersive X-ray detector running Iridium Ultra software. Broad beam analyses were conducted with this SEM in 100 x 100 µm and 50 x 50 µm areas of two of the larger lithic clasts and the interclast regions to produce major and minor element analyses. CIPW norms, liquid density, liquid viscosity, and liquidus temperatures were calculated using a spreadsheet from K.T. Hollocher (2004; [https://view.officeapps.live.com/op /view.aspx](https://view.officeapps.live.com/op%20/view.aspx)? src=https%3A%2F%2Fgeologynet.com%2Fprograms%2Fcipwnormexcel.xls&wdOrigin= BROWSELINK). Quantitative wavelength-dispersive analyses of individual minerals were obtained with a fully automated JEOL 8200 electron microprobe operated at 15kV with a focused beam, a beam current of 20 nA, calibrated with pure oxide and natural mineral standards (Simon et al., 2022).