TY - JOUR
T1 - Provenance of Block Fields Along Lunar Wrinkle Ridges
AU - French, Renee A.
AU - Watters, Thomas R.
AU - Robinson, Mark S.
N1 - Funding Information:
We wish to thank Ernst Hauber and an anonymous reviewer for insightful comments and suggestions that greatly improved the paper. This work would not have been possible without the dedication and hard work of the LROC team, not only in data acquisition and distribution but in support as well. We thank groups at ASU and UA for processing of NAC stereo pairs to DEMs, data that are the backbone of this work. We gratefully acknowledge the LRO engineers and technical support personnel. This work was supported by the LRO Project and an ASU LROC Contract (TRW). Data are available on the Smithsonian Figshare site (https://dx.doi.org/10.25573/data.9955277).
Funding Information:
We wish to thank Ernst Hauber and an anonymous reviewer for insightful comments and suggestions that greatly improved the paper. This work would not have been possible without the dedication and hard work of the LROC team, not only in data acquisition and distribution but in support as well. We thank groups at ASU and UA for processing of NAC stereo pairs to DEMs, data that are the backbone of this work. We gratefully acknowledge the LRO engineers and technical support personnel. This work was supported by the LRO Project and an ASU LROC Contract (TRW). Data are available on the Smithsonian Figshare site ( https://dx.doi.org/10.25573/data.9955277 ).
Publisher Copyright:
Published 2019. This article is a U.S. Government work and is in the public domain in the USA.
PY - 2019/11/1
Y1 - 2019/11/1
N2 - Block fields and associated relatively high reflectance material along wrinkle ridge summits are revealed in meter-scale Lunar Reconnaissance Orbiter Camera images. Wrinkle ridges with block fields in Mare Australe, Crisium, Fecunditatis, Frigoris, Nubium, the northern half of Oceanus Procellarum, Serenitatis, and Tranquillitatis are evenly distributed, and block density generally increases with wrinkle ridge slope. The median cross-sectional area (proxy for diameter) of the 1,368 blocks measured in this study is ~7 m2, and 75% of these blocks are ≤~14 m2. We propose that the largest variation in cross-sectional area of the blocks is related to substrate physical properties of the mare basalt and not a function of the slope on which they occur, suggesting that physical properties rather than slope are a stronger control on block size. The maximum length of blocks may constrain the minimum basalt flow thickness or joint width; our block measurements suggest basalt flows ~2–14 m thick, agreeing with previous estimates. The data suggest that blocks originate from mare basalt layers that buckle and break as a result of movement along ridge-forming thrust faults. High reflectance material associated with wrinkle ridge blocks likely represents freshly exposed rock and soil. Meter-scale blocks may erode relatively quickly due to collisional disruption, indicating recent downslope movement of regolith exposing preexisting blocks or blocks formed and exposed by recent activity on ridge-forming faults.
AB - Block fields and associated relatively high reflectance material along wrinkle ridge summits are revealed in meter-scale Lunar Reconnaissance Orbiter Camera images. Wrinkle ridges with block fields in Mare Australe, Crisium, Fecunditatis, Frigoris, Nubium, the northern half of Oceanus Procellarum, Serenitatis, and Tranquillitatis are evenly distributed, and block density generally increases with wrinkle ridge slope. The median cross-sectional area (proxy for diameter) of the 1,368 blocks measured in this study is ~7 m2, and 75% of these blocks are ≤~14 m2. We propose that the largest variation in cross-sectional area of the blocks is related to substrate physical properties of the mare basalt and not a function of the slope on which they occur, suggesting that physical properties rather than slope are a stronger control on block size. The maximum length of blocks may constrain the minimum basalt flow thickness or joint width; our block measurements suggest basalt flows ~2–14 m thick, agreeing with previous estimates. The data suggest that blocks originate from mare basalt layers that buckle and break as a result of movement along ridge-forming thrust faults. High reflectance material associated with wrinkle ridge blocks likely represents freshly exposed rock and soil. Meter-scale blocks may erode relatively quickly due to collisional disruption, indicating recent downslope movement of regolith exposing preexisting blocks or blocks formed and exposed by recent activity on ridge-forming faults.
KW - Moon, surface
KW - geological processes
KW - tectonics
UR - http://www.scopus.com/inward/record.url?scp=85075259858&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85075259858&partnerID=8YFLogxK
U2 - 10.1029/2019JE006018
DO - 10.1029/2019JE006018
M3 - Article
AN - SCOPUS:85075259858
SN - 2169-9097
VL - 124
SP - 2970
EP - 2982
JO - Journal of Geophysical Research: Planets
JF - Journal of Geophysical Research: Planets
IS - 11
ER -