Conference PaperPDF Available

Is the moon still active?

Authors:
Conference on Planetary Sciences and Exploration , 12-14 Dec. 2011, PRL, Ahmedabad, India
97
IS THE MOON STILL ACTIVE?
N. Srivastava1*, D. Kumar1, R. P. Gupta2
1 PLANEX, Physical Research Laborato
ry, Ahmedabad - 380009, India,
2 Department of Earth Sciences, IIT Roorkee, Roorkee  247667, India.
*E-mail: sneeraj@prl.res.in
Introduction:
Unlike the dynamic Earth, which still clearly exhibits volcanic eruptions from time to time, it is
generally believed that the Moon had a rather short extrusive phase. Laboratory studies of lunar samples
from Apollo and Luna missions have indicated that the major episode of volcanic activity on the Moon
started ~ 4 b.y. but probably ceased ~ 3 b.y. due to reduction of heat producing radioactive elements,
cooling and contraction [1-3]. Global remote sensing observations using high resolution images from
recent missions have extended this time frame to ~ 1 b.y., at least for some of the places on the Moon [3
 5]. In addition to these, possibilities have been put forward for post-impact volcanic modifications in
certain Copernican craters (< 800 m.a.) [6-8] and evidences have been put forward for recent gas release
at certain places such as at Ina [9] and the ones where Lunar Transient Phenomenon (LTPs) have been
observed [10].
Here, we have carried out detailed investigations of a conspicuous resurfacing (figure 1a, b) inside the
Lowell crater (12.9°S, 103.1°W), located in the NW quadrant of Orientale basin, on the Western limb of
Moon, to understand the surface morphology and nature of this resurfacing.
Datasets Used:
LROC-NAC (Lunar Reconnaissance Orbiter) [11] and MI  VIS (Kaguya) [12] data with spatial
resolutions of ~ 1 m and 20 m respectively, have been used to study the surface morphology. For
compositional investigations, global mode hyperspectral M3 data from Chandrayaan-1 mission [13, 14]
have been used. The spectral range, spectral resolution and spatial resolution of the used M3 data are
460  2896 nm, 20- 40 nm and 140 m respectively. The I/F values have been derived from the radiance
values using cosine transformation for data normalisation [15].
Results:
Based on detailed morphological studies, it is interpreted that the conspicuous resurfacing inside
Copernican Lowell crater (figure 1 a, b) would have formed as a result of recent volcanic activity in the
region. Various features characteristic of a volcanic terrain have been found. Some of these include
volcanic cone, lava pond, fresh flows, lava piles, collapse pits etc. Compositionally, the volcanic unit is
found to be basaltic since its spectral reflectance signature shows distinct absorptions centred ~ 1 and
2.2 m indicating presence of High Ca-pyroxene in the unit (figure 1c: L1). The adjoining areas show
feldspathic to noritic character (L2). The unit exhibits high albedo possibly due to its fresh nature and
mixing of feldspathic crustal material.
Conference on Planetary Sciences and Exploration , 12-14 Dec. 2011, PRL, Ahmedabad, India
98
The surface of this unit is smooth (figure 1a) and has very few small depressions. These depressions do
not show characteristics of impact craters such as circular appearance, raised rims, and ejecta blanket
found in other adjacent areas. Thus, they may be either ghost craters or small pits on the basaltic surface.
We infer from this study that endogenic activities on the Moon might not have ceased completely as
believed earlier.
Acknowledgements: LRO - LROC, KAGUYA - MI and Chandrayaan-1 M3 data teams are gratefully
acknowledged for providing data through public access web portals.
References:
[1] Head J.W. (1976) Rev. Geophys. Space Phy., 14, 265-300. [2] Schultz P.H. and Spudis P.D. (1989)
Nature, 302, 233-236. [3] Hiesinger H. et. al. (2003) JGR 108, 5065 [4] Jolliff B.L. et al., (2011)
Nature Geoscience, doi: 10.1038/NGEO1212 [5] Whitten J., et al. (2011) J G R, 116, E00G09. [6]
Hartmann W.K. (1968), Commun. Lunar and Planetary Lab., Univ. Arizona 7, 145-156. [7] Storm R.G.
and Fielder G. (1968), Nature 217, 611-615. [8] Chauhan P. et al. (2011) LPSC 42, Abstract #1341. [9]
Schultz P.H. et al. (2006), Nature 444, 184  186. [10] Crotts A.P.S. and Hummels C. (2009), ApJ 707,
1506 doi:10.1088/0004-637X/707/2/1506. [11] Robinson M.S., et al. (2010), Space Sci. Rev. 150, 81-
124. [12] Ohtake M., et al. (2008) Adv. in Space Res. 42, 301304. [13] Goswami J. N. & Annadurai M.
(2009), Curr. Sci. 96, 486491. [14] Pieters C. M., et al.(2009) Curr. Sci. 96, 500505.[15] Isaacson P.
(2011) http://m3.jpl.nasa.gov/ pubs / Isaacson_ M3Data Worksho p _ LPSC.pdf .
Figure 1: a: LROC-NAC image of Lowell crater floor
showing the smooth resurfacing; b: M3 750 nm image
showing the extent of the volcanic resurfacing inside
Lowell crater; Yellow arrow indicates the resurfacing and
L1, L2 corresponds to locations for which reflectance
spectra have been derived; c: Single pixel spectra of L1and
L2 smoothened by moving average span of 3 .
... The region is geologically important since it is located inside Orientale basin, the proto-type multi-ring basin on the Moon. In addition to that, a distinct fresh resurfacing has been reported in the region (Srivastava et al., 2011), whose origin is been debated Wöhler et al., 2014;Plescia and Spudis, 2014;Gupta et al., 2014). Surface topography and morphology of the Lowell crater region and age-dating of Lowell crater have been the main aspects of the study. ...
... It occupies an area of ~64 km 2 . Based on its surface topography, surface morphology, surface composition, and extensional geological setting for the Lowell crater and Crater S,Srivastava et al. (2011 have proposed that at least a part of it represents ~ 2-10 Ma old recent volcanic activity in the region, after the impact melts from Crater S were emplaced. Using M 3 data, the flows were found to be basaltic in composition, in contrast to the noritic-feldspathic-spinel composition of the Crater S and its various ejecta units (impact melts and clastic ejecta emplaced towards the interior and exterior of the Lowell crater respectively). ...
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Surface topography, surface morphology and crater chronology studies have been carried out for the Lowell crater region (occupying ~198×198 km2 in the northwestern quadrant of the Orientale basin) using Kaguya TC-DTM, LRO-WAC data, and Chandrayaan-1 M3-750 nm image, to characterize and date Lowell impact event and to identify and assess the geological importance of the Lowell crater and effect of pre-existing geological conditions on the present day appearance of Lowell crater. The Lowell crater has been found to be polygonal in shape with an average diameter of 69.03 km. Its average rim height and depth from pre-existing surface are 1.02 km and 2.82 km respectively. A prominent central peak with average height of 1.77 km above the crater floor is present, which could have exposed undifferentiated mantle rocks. The peak exhibits a pronounced "V" shaped slumped zone on the eastern side and a distinct "V" shaped depression in the adjacent region on the crater floor. Several other peculiarities noticed and mapped here include W-E asymmetry in the degree of slumping of the walls and height of the topographic rim, N-S asymmetry in the proximal ejecta distribution with most of the material lying in the northern direction, concentration of exterior melt pools in the northeastern direction only, presence of several cross cutting pre-existing lineaments on the crater walls, presence of a superposed rayed crater on the eastern wall, and a geologically interesting resurfaced unit, which could be an outcome of recent volcanic activity in the region. It has been inferred that the Lowell crater formed due to impact of a ~5.7 km diameter bolide in the Montes Rook region. The impact occurred at an angle of ~30-45° from the S-SW direction. The age of the Lowell crater has been estimated as 374±28Ma, therefore it is a Younger Copernican crater consistent with the possibility expressed by McEwen et al. (McEwen, A.S., et al. [1993]. J. Geophys. Res. 98(E9), 17207-17231). Pre-existing topography and morphology has played a key role in shaping up the present day Lowell crater.
... However, by combining topographical, morphological with compositional studies in the geological context, we can derive some clues to the mechanism by which the flows have formed. Such a study has been carried out inside the~66 km diameter Lowell crater at 13.0°S, 103.4°W [43,70]. Here, the resurfacing extends from a small satellite crater on the eastern wall and terminates on the crater floor. ...
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  • W K Hartmann
  • R G Storm
  • G Fielder
  • P Chauhan
Hartmann W.K. (1968), Commun. Lunar and Planetary Lab., Univ. Arizona 7, 145-156. [7] Storm R.G. and Fielder G. (1968), Nature 217, 611-615. [8] Chauhan P. et al. (2011) LPSC 42, Abstract #1341. [9]
  • J W Head
Head J.W. (1976) Rev. Geophys. Space Phy., 14, 265-300. [2] Schultz P.H. and Spudis P.D. (1989) Nature, 302, 233-236.
  • H Hiesinger
Hiesinger H. et. al. (2003) JGR 108, 5065 [4] Jolliff B.L. et al., (2011) Nature Geoscience, doi: 10.1038/NGEO1212 [5] Whitten J., et al. (2011) J G R, 116, E00G09. [6]
  • W K Hartmann
Hartmann W.K. (1968), Commun. Lunar and Planetary Lab., Univ. Arizona 7, 145-156. [7] Storm R.G. and Fielder G. (1968), Nature 217, 611-615.
  • P H Schultz
Schultz P.H. et al. (2006), Nature 444, 184 – 186. [10] Crotts A.P.S. and Hummels C. (2009), ApJ 707, 1506 doi:10.1088/0004-637X/707/2/1506. [11] Robinson M.S., et al. (2010), Space Sci. Rev. 150, 81
  • M Ohtake
Ohtake M., et al. (2008) Adv. in Space Res. 42, 301304. [13] Goswami J. N. & Annadurai M. (2009), Curr. Sci. 96, 486491. [14] Pieters C. M., et al.(2009) Curr. Sci. 96, 500505.[15] Isaacson P. (2011) http://m3.jpl.nasa.gov/ pubs / Isaacson_ M3Data Worksho p _ LPSC.pdf.