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Lineae are elongated features that are associated with abundant additional parallel lineaments that occur together in narrow elongated topographic highs. Lineae have also been termed fracture belts, densely lineated material, and more recently, groove belts (see summary of nomenclature in [1,2]). Excellent examples of groove belts (Antiope, Hippolyta, and Molpadia Lineae) are described from Lavinia Planitia (e.g. [3,4]). Key outstanding questions about groove belts include the nature of the lineae (fractures, graben?), their origin (tectonic, surface manifestation of dykes?), the origin of their associated linear elevated topography (extension, compression, shear?), their relationship to surrounding regional and global geologic units (prior to, simultaneous, post-dating?) the nature of the material being deformed (similar to or different than surrounding units?), and establishing their relationship to other associated features (coronae, novae, rift zones, shield volcanoes, etc.). Key questions for our ongoing mapping include 1) distinguishing the radial and belt parallel grabens in more detail, 2) assessing their dyke-related versus purely tectonic origin (e.g., presence of pit craters, feeding of flows, etc.), 3) examining stratigraphic and morphological relationships with the more regional components of the groove belts (mapped in green and blue in Fig. 2), and 4) assessing the relationship of these central features to coronae, novae and related features located in adjacent areas to the groove belt (cf. in Wawalag Planitia to the south [10]). Jokwa linea extends for 1700 km from within southeastern Stanton Quadrangle, V-38 and eastward into the adjacent Taussig Quadrangle, V-39, where it has been mapped at 1:5,000,000 scale [5]. However, no Quadrangle scale mapping exists for V-38. For our geological mapping study of Jokwa Linea, we used full-resolution (75 m/pixel) Magellan SAR images and its altimetry data in ArcGIS ArcMap v. 10.3; JMARS (Java Mission-planning and Analysis for Remote Sensing) [6] and ArcGIS 10.3 ArcScene were used to create topographic profiles and digital elevation models (DEMs), respectively. Geological units are distinguished based on changes in radar properties, topography, morphology and stratigraphic relationships (e.g., [1]). Our initial mapping reported here is from a 620 km long section of the western half of Jokwa Linea. Multiple sets of lineaments have been mapped (so far more than 17,000). Our mapping includes identifying, distinguishing rift-faulting from graben-related dykes using criteria in [7], and assessing their relationships and timing. Our mapping has also identified and characterized 9 magmatic centres in western Jokwa linea (comprising corona and nova and corona-nova [8, 9]). In the eastern portion of the map, circumferential grabens (interpreted to overlie subsurface dykes) are associated with coronae. There are multiple radiating graben sets (each interpreted to represent the surface expression of dykes on the basis of associated lava flows and pit craters) in the west, some extending for more than 400 kilometers. Major parts of these radiating graben systems (dyke swarms) curve into the strike of the broader groove belt and match its regional trend, which we interpret to indicate the role of regional stresses in dyke propagation direction. Age relationships between swarms and associated magmatic centres (from cross cutting relationships), and flows fed from graben. References: [1] Ivanov, M.A., Head, J.W. Space Sci., 2011, V. 59, P.1559-1600.[2] Ivanov, M.A., Head, J.W (2015), 113-114, 10–32. [3] Ivanov, M.A., Head, J.W. (2001) USGS Scientific Inves-tigations Map 2684. [4] Fernández, C. et al (2010) Icarus, 206, 210-228. [5] Brian, A.W. et al (2005) USGS, SIM 2813. [6] Christensen, P. R. et al. (2009) AGU Fall Meeting, Abstract #IN22A-06. [7] Graff, J.R. et al (2018) Icarus, 306, 122-138. [8] Buchan, K.L., Ernst, R.E. (2021) Gond. Res., 100, 25–43. [9] Grosfils, E.B., Head, J.W (1994) GRL, 21, 701–704. [10] Ounar J. et al. (2022) 53rd LPSC. |
