Topography and crustal thickness data from LOLA altimetry were used to test the validity of 98 candidate large lunar basins derived from photogeologic and earlier topographic and crustal thickness data, and to search for possible new candidates. We eliminate 23 previous candidates but find good evidence for 20 new candidates. The number of basins > 300 km diameter on the Moon is almost certainly a factor 2 (maybe 3?) larger than the number of named features having basin-like topography

Frey, Herbert V.

Meyer, H. M.

NASA Technical Reports Server

IMPROVING THE INVENTORY OF LARGE LUNAR BASINS: USING LOLA DATA TO TEST PREVIOUS 
CANDIDATES AND SEARCH FOR NEW ONES   H.V. Frey, Geodynamics Branch, Goddard Space Flight Center, Green-
belt, MD 20771, Herbert.V.Frey@nasa.gov, H.M. Meyer, Geology & Environmental Geosciences, College of Charleston, Char-
leston, SC, and G.C. Romine, Physics & Astronomy, San Francisco State University, San Francisco, CA. 
 
Summary:  Topography and crustal thickness data from 
LOLA altimetry were used to test the validity of 98 candidate 
large lunar basins derived from photogeologic and earlier 
topographic and crustal thickness data, and to search for 
possible new candidates. We eliminate 23 previous candi-
dates but find good evidence for 20 new candidates. The 
number of basins > 300 km diameter on the Moon is almost 
certainly a factor 2 (maybe 3?) larger than the number of 
named features having basin-like topography. 
Introduction: Unified Lunar Control Net 2005 data [1] 
and model crustal thickness data [2] were previously used to 
search for possible previously unrecognized large lunar im-
pact basins [3,4]. An inventory of 98 candidate topographic 
basins > 300 km in diameter was found [5]. This includes 33 
named features (only those having basin-like topography) out 
of the 45 listed by Wilhelms [6], 38 additional Quasi-
Circular Depressions (QCDs) found in the ULCN2005 topo-
graphy, and 27 Circular Thin Areas (CTAs) found in model 
crustal thickness data [2]. Most named features and adddi-
tional QCDs have strong CTA signatures, but there may be a 
class of CTAs that are not easily recognized in the old and 
low resolution ULCN2005 topography. 
Lunar Orbiter Laser Altimeter (LOLA) data have recent-
ly become publically available. We used these data to (a) 
refine the center and ring diameters of known basins, (b) test 
the viability of the candidate basins previously found (as 
described above), and (c) search for additional candidate 
basins not revealed by the earlier lower resolution data. We 
used the LOLA topography directly but also a recent new 
model crustal thickness data that includes Kaguya gravity 
data [7]. We repeated a “Topographic Expression” (TE) and 
a “Crustal Thickness Expression” (CTE) scoring exercise 
originally done with the basins found in ULCN and earlier 
model crustal thickness data [5]. Each candidate was scored 
on a scale from 0 (no topographic basin or circular thin area 
signature) to 5 (strong circular low or strong circular thin 
area signature). These were combined into a total score used 
to rank the probability for each candidate basin. We used the 
same GRIDVIEW software to stretch, contour and profile the 
LOLA and new crustal thickness data as was done with the 
ULCN2005 and older model crustal thickness data. 
Figure 1 compares ULCN2005 and LOLA topography 
for three named basins. LOLA data clearly shows better the 
circular basin and raised rim structure of obvious features 
like Orientale or Poincare. Orientale rates a 5 Topographic 
Expression (TE) score in both data sets. Poincare QCD struc-
ture, evident in the older data, is even more obvious in the 
higher resolution LOLA data. The TE scores for this basin 
are 3 and 4 for ULCN and LOLA topography, respectively. 
Australe was previously noted as not having basin-like struc-
ture in ULCN2005 topography [5]; the same is true in LOLA 
data. Australe could have had a TE score of -1 or -2 in 
ULCN data; from the LOLA data we give it a 0. 
Figure 2 shows a similar comparison between older [2] 
and more recent [7] crustal thickness data for the Lorenz 
Basin. The CTE score goes up considerably in the new data. 
 
 
Figure 1a. ULCN2005 (left) and LOLA (right) topogra-
phy for the area around the (top to bottom) Orientale 
(D=930 km), Poincare (D=331 km) and Australe (D=880 
km) Basins, all named in Wilhlems' [6] list. Contour in-
terval is 400 m for both. The much improved resolution of 
the LOLA data is obvious. Orientale and Poincare are 
obvious basins; Australe lacks basin-like structure. 
 
 
 
 
 
 
 
 
 
 
 
Figure 2. Older [2] (left) and more recent [7] (right) mod-
el crustal thickness data for the area around the Lorenz 
Basin. A weak Circular Thin Area (CTA) structure was 
suggested by the older data (CTE score = 1) but is very 
obvious in the newer model (CTE score > 4). 
https://ntrs.nasa.gov/search.jsp?R=20120008059 2019-08-30T20:16:37+00:00Z
AN IMPROVED INVENTORY OF LARGE LUNAR BASINS:  H.V. Frey et al. 
 
Testing the previous candidates:  For all previous can-
didates two or more of us re-evaluated the TE score (HF, 
GR, HM) and the CTE score (HF, HM). We are in good 
agreement for nearly all candidates, and especially on which 
candidates should be eliminated from the earlier inventory. 
Named Basins: The earlier study [5] found no topographic 
basin structure for 10 named basins [6]. The same 10 are 
again eliminated because LOLA data also shows no basin-
like structure. In addition, Sikorsky-Rittenhouse is now 
dropped because LOLA data show that the diameter is ac-
tually < 300 km [8], the cutoff for our inventory. Additional 
QCDs: We eliminate 11 additional QCD candidates from the 
earlier study [5] mostly because the improved resolution of 
LOLA data show that both the apparent large circular struc-
ture and the depth of the proposed candidate basin can be 
explained by clusters of deep smaller craters [8] (see Figure 
3). Other CTAs: We also removed 11 CTA candidates from 
the earlier inventory. In some cases the new model crustal 
thickness data [7] fails to show the CTA signature found in 
the earlier model data; sometimes that area actually has posi-
tive topographic relief [8]. In other cases clusters of small 
and deep craters likely explain the apparent CTA structure 
previously observed [9]. Overall: We deleted a total of 23 
candidates from the earlier inventory [5] including all fea-
tures with summary scores (TE + CTE) < 3. Thus 75 of the 
original 98 candidates survive. To this we add a number of 
new candidate large basins as described below. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
New Candidate Basins: A number of new candidate ba-
sins were revealed by LOLA data [9, 10]. Though generally 
subtle, often overprinted by other more prominent basins, 
and small, at least one is of Imbrium size (Figure 4) and has 
both QCD and CTA structure. The newer crustal thickness 
data also suggests several new candidate basins [9], some of 
which do not have obvious QCD structure (Figure 5).  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Summary: LOLA based topographic and crustal thickness 
data suggest 23/98 candidate basins found using older data 
should be dropped. But these same data suggest there could 
be 20 new candidates that should be added to the inventory: 
these include 12 new QCDs and 8 new CTAs, all with sum-
mary scores > 3. There are 83 candidates with summary 
scores > 4 and 63 with summary scores > 5. The likely in-
ventory is at least a factor 2 (maybe a factor 3) greater than 
the number of named basins having basin-like structure. 
 
References. [1] Archinal, B.A. et al. (2006) USGS Open File 
Report 2006-1367. [2] Wieczorek, M.A. et al. (2006) New 
views of the Moon: Reviews in Mineralogy and Geochemi-
stry, vol. 60, 221-364, 2006. [3] Frey, H.V. (2008) LPSC 39, 
abstract #1344. Frey, H.V. (2008) Workshop on Early Solar 
System Impact Bombardment, Houston, TX. [4] Frey, H.V. 
(2009) LPSC 40, abstract #1687. [5] Frey, H.V. (2010) 
Chapter 2, GSA Special Publication Recent Advances and 
Current Research Issues in Lunar Stratigraphy. [6] Wil-
helms, D.E, (1987) The Geologic History of the Moon, 
USGS Professional Paper 1348. [7] Wieczorek, M.A., pri-
vate communication. [8] Romine, G. and H. Frey (2011) 
LPSC 42, abstract #1188. [9] Meyer, H. and H. Frey (unpub-
lished data). [10] Frey, H. and G. Romine (2011) LPSC 42 
abstract #1190. 
Figure 4. Candidate GL-7 
is an possible Imbrium-size 
basin found in LOLA data 
(above). Topographic con-
tours are 500 m; crustal 
thickness data (left) has 2.5 
km contours and shows a 
structure supporting the 
existence of this basin. 
 
 
Figure 3. ULCN (left) and LOLA (right) topographic 
data for the area near QCD T12 [5]. The apparent large 
roughly circular low can be explained by the cluster of 
small and deep craters revealed in the LOLA data, as 
indicated in the bottom panels. 
Figure 5 (below). Candidate CTA basin HM-15 [9] is  ~ 
304 km in diameter. The CTA signature in the new mod-
el crustal thickness data [7] is obvious, but the topo-
graphic signature is not convincingly basin-like. 
 
 
HM-15 
8N, 83W 


Improving the Inventory of Large Lunar Basins: Using Lola Data to Test Previous Candidates and Search for New Ones

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