MerCatSS README =============== MerCatSS – The Mercury Catalog of Shortening Structures was compiled at a mapping scale of 1:1,000,000 using stream mapping at a constant vertex placement of 2 km: Editor > Options > General > Stream Mode > Stream tolerance > Set to 2 km (=2000 map units as map units were defined accordingly) and grouped 5 points together > Start editing > Press F8 to activate streaming mode This line digitization process was carried out in ArcMap Desktop, as ArcGIS Pro did not provide this functionality as of the year 2025. Three categories of potential shortening structures were mapped: a) "Lobate scarp": Visible fault breaks of lobate scarps. This category includes compound scarps of "wrinkle ridges", i.e., fault breaks bounding high-relief ridges of likely tectonic origin. b) "Wrinkle ridge": In addition to mapping visible compound scarps of "wrinkle ridges", this category traces the crest of a high-relief ridge bound by fault breaks. If two antithetic scarps bounding a wrinkle ridge cannot be resolved on data (because they are too narrowly spaced), they were mapped only as one wrinkle ridge. c) "Tentative high-relief ridge": Traces of high-relief ridge crests of probable anticlines or scarps that lack visible fault breaks (either because there was no surface break or due to degradation). For "lobate scarps", the following parameters are included in its attribute table: "OBJECTID" ---------- - Automatically generated in a chronological way, i.e., higher numbers are features created later in the project's duration. Sequence has gaps as features were deleted and often remapped according to re-interpretations throughout the project. "SHAPE *" --------- - Automatically generated; defines shape type, which is Polyline for all mapped features. "Object_ID_copy" ---------------- - A copy of OBJECTID for maintenance purposes (only in *.lpkx) "type" ------ - Two different types: Certain & Tentative. If a fault break is certain in one area but tentative elsewhere, its entire trace is mapped as Certain. "byrne_2014" ------------ - Has the feature been recognized in the global structure map by Byrne et al. (2014)? > yes (verified Byrne et al.) or no (newly discovered) "lat" ----- - Latitude (in decimal degrees) of the central point, i.e., mid-point, on the line feature. - Calculate Geometry > Y (lat) Central point y-coordinate [coordinate system of data frame; Units: Decimal Degrees] "lon" ----- - Longitude (in decimal degrees) of the central point, i.e., mid-point, on the line feature. - Calculate Geometry > X (lon) Central point x-coordinate [coordinate system of data frame; Units: Decimal Degrees] "SHAPE_length" -------------- - SHAPE_length (in meters) is populated automatically, giving the planar length of a line feature on a global cylindrical projection (strong distortion at higher latitudes) "SHAPE_length_geodetic" ----------------------- - Calculate Geometry > column SHAPE_length_geodetic = Length (geodesic); unit is meters - Gives the "actual" length of the feature on the surface of a sphere "width_max" ----------- - Measured maximum width (in meters; in steps of 1000 m, corresponding to ~3 MDIS pixels) - Max. extent of scarp backarc until it reassumes background elevation or distance between front- and backscarp (might therefore be identical to widths of a co-assigned wrinkle ridge). - Performed measurement either visually in MDIS mosaic or in topographic profile, whatever worked better - For step-like scarps where a width cannot be determined: Left blank, i.e. value "width_relief_max" ------------------ - Same as width_max, but measurement taken at the location along the scarp that has the maximum relief (relief_max) "relief_max" ------------ - Measure max. relief (in meters; vertical accuracy of the DTMs is 50 m) - Measure at the point most representative of actual scarp relief, i.e., away from overprint by craters or background topography affecting relief etc. "relief_over_length" -------------------- - Calculate Field > relief_over_length = !relief_max! / !SHAPE_length_geodetic! - Used as proxy for displacement over length (D/L) "complex" --------- - Is the feature part of a complex or "cluster"? - Name of lobate scarp (LS) or wrinkle ridge (WR) complex the feature belongs to; nomenclature "[LS or WR]_Quadrangle number_[closest named crater/planum/planitia/albedo feature or already existing official scarp name; standardize any special characters]#", e.g., "WR_H-03_Brahms01" or “LS_H-11_Discovery_Rupes” (quadrangle based on where the majority of the complex is). - If a scarp is not part of an obvious complex, leave the field empty. - If a wrinkle ridge is part of a larger lobate scarp complex, it is embedded in the complex by using a second prefix-label, e.g., “LS_WR_H-02_Antoniadi-Endeavour-Victoria” are all wrinkle ridges and wrinkle-ridge-compound-scarps that are part of the larger complex “LS_H-02_Antoniadi-Endeavour-Victoria”. - A scarp is only included in a WR-complex if it aligns with a wrinkle ridge along more than ~50% of its length. "name" ------ - Is the feature already officially named? - Name will only be filled in for such features that trace the actual named line feature as displayed on the USGS Planetary Nomenclature website. This means that a complex named after a scarp that is officially named, e.g., LS_H-14_Belgica_Rupes, consists of 31 scarps, of which only three scarps actually bear that official name. "end-to-endpoint_bearing" ------------------------- - Bearing of line connecting endpoints of each polyline; 0° is north, 90° is east, 180° is south, 270° is west - re-project to mercator (no angular distortion) - Calculate Geometry > column end_to_endpoint_bearing = Line bearing "end-to-endpoint_distance" -------------------------- - Geodetic length (in meters) of the line connecting the end points of a scarp. "lobateness" ------------ - Divide total length of a scarp (SHAPE_length_geodetic) by the distance between its end points (end-to-endpoint_distance) - Calculate Geometry > lobateness = !SHAPE_length_geodetic! / !end_to_endpoint_distance! - Measure of the sinuosity of a scarp. Theoretical minimum value of 1 would be a perfectly linear scarp. "intracrater" ------------- - Is the feature located within an impact crater or morphologically distinct, closed basin (not an ancient basin as mapped by Orgel et al. (2020))? > Enter crater formation periods (pre-Tolstojan to Mansurian) derived from morphologic degradation state (according to Fig. 2 in Banks et al. (2015)). Leave the field blank if not (partially) within a crater. - Add suffix “_part” if the scarp is only partially within a crater; add “_cont” if the scarp segment is fully within a crater, but appears to be a continuation of a complex outside the crater, e.g., “pre-Tolstojan_part” or “Calorian_cont”. "basin_concentric" ------------------ - Is the feature concentric to a large impact basin according to the basin catalog by Orgel et al. (2020) (that we amended with six additional basins)? - If yes, parameter is the name of the basin according to Orgel et al. (2020), e.g., “Andal-Coleridge basin” or “b87 basin”. The six basins that we added have the prefix "nb" for new basin, e.g., "nb02 basin". - Only valid out to a maximum of 1 basin-radius away from the basin outline. "ghostcrater" ------------- - Does the scarp follow a quasi-circular trace or is it part of a cluster that trace a quasi-circular outline? "WR-LS transition" ------------------ - Is the feature associated with a transition between a "true lobate scarp" (not on smooth plains material) to a wrinkle ridge on an adjacent plain? > type in “yes”, otherwise leave blank Will be added in future releases: --------------------------------- * For lobate scarp: D/L, where displacement D is approximated by estimating angle of faulting based on max. back-arc extent (width_max) of a scarp * For lobate scarp: Ages and age errors, derived as absolute model ages (AMAs) from crater size-frequency distribution measurements on suitable floors of craters superposed by a scarp * For wrinkle ridges and tentative high-relief ridges: Add more of the parameters that are already present for lobate scarps.