Remote sensing studies of the Lomonosov‐Fleming region of the Moon

Abstract

[1] Lomonosov-Fleming is a 620 km, pre-Nectarian impact basin centered at 19°N, 105°E. Clementine multispectral images and a variety of spacecraft photographs were used to investigate the composition and origin of geologic units in the region. Mare basalt deposits in the Lomonosov-Fleming region are small and exhibit varying degrees of highlands contamination. Four previously unrecognized dark mantle deposits of probable pyroclastic origin were identified and mapped. A major expanse of cryptomare was mapped in and around the Lomonosov-Fleming basin. Spectral and chemical data obtained for dark-haloed craters (DHC) established that these impact craters excavated mare basalt from beneath higher-albedo highlands-rich surface units. The buried basalts exposed by DHCs in the region exhibit a variety of compositions, which range from very low titanium basalt to intermediate TiO 2 mare basalt. Nectarian-aged units with subjacent cryptomare are much more extensive than Imbrian-aged deposits with underlying basalt. At least some of the buried mare basalts in the region may have been emplaced during pre-Nectarian time. While both impact basins and craters played a role in cryptomare formation by transporting highlands material to mare surfaces, the evidence indicates that most of the cryptomare inside the basin are of the distal basin ejecta type. The enhanced FeO and TiO 2 abundances exhibited by these cryptomare surfaces, usually light plains units, demonstrate that ballistic erosion and sedimentation played an important role in their formation.

Lunar cryptomaria: Mineralogy and composition of ancient volcanic deposits

“…Further geochemical and visible to near-infrared (VNIR) spectral analyses suggested that the compositions of DHCs were consistent with mare basalt material (Maxwell and Andre, 1981;Hawke and Spudis, 1980;Hawke and Bell, 1981;Bell and Hawke, 1984;Blewett et al, 1995;Giguere et al, 2003;Hawke et al, 2005;Lawrence et al, 2008). DHC VNIR spectral measurements are dominated by two pyroxene absorption features centered near 1 μm and 2 μm.…”

“…Frigoris, Hercules, and Tarunitus are relatively "young" cryptomaria, formed from the continuous ejecta deposits of Eratosthenian-and Copernican-aged craters overlying and partially covering exposed maria (Wilhelms and McCauley, 1971;Giguere et al, 2003), compared with the impact basin events that formed the larger cryptomaria. The formation mechanism for relatively "young" cryptomaria implies that the (Fig.…”

“…Ancient lunar volcanic deposits, known as cryptomaria (Head and Wilson, 1992), have been identified beneath basin ejecta deposits (e.g., Spudis, 1979, 1983;Hawke and Spudis, 1980;Hawke and Bell, 1981;Bell and Hawke, 1984;Hawke et al, 1993Hawke et al, , 2002Hawke et al, , 2005Hawke et al, , 2013Head et al, 1993;Antonenko et al, 1995;Blewett et al, 1995;Mustard and Head, 1996;Antonenko, 1999;Giguere et al, 2003;Campbell and Hawke, 2005;Lawrence et al, 2008). The name assigned to these ancient volcanic deposits, cryptomaria, implies that these ancient volcanic deposits are mare basalts.…”

“…At VNIR wavelengths, the center wavelength of the different absorption bands provides information about the composition of the pyroxene; longer wavelength 1 μm and 2 μm absorption features are associated with Fe-and Ca-rich pyroxenes (Adams, 1974;Cloutis and Gaffey, 1991) and are consistent with mare basalts. As a result of the systematic change in band center with mineral composition, many spectral studies of DHCs have focused on measuring the position of the pyroxene absorption band centers and comparing those values to the composition of known lunar samples (e.g., Bell and Hawke, 1984) or exposed mare basalt deposits from the same image scene (Blewett et al, 1995;Giguere et al, 2003;Hawke et al, 2005).…”

Volcanism and tectonism across the inner solar system: an overview

“…the youngest basin on the Moon) and the emplacement of its ejecta, which is an important stratigraphic marker horizon. Although Giguere et al (2003) and Hawke et al (2005) reported that the buried basalts in the Lomonosov -Fleming and the Balmer -Kapteyn regions are very-low-to intermediate-Ti basalts, sampling and subsequent analyses are required to understand the true nature of cryptomaria.…”