Geological Mapping of the Fortuna Tessera Quadrangle

Introduction: The Fortuna Tessera quadrangle (V–2, Fig. 1) is in the northern hemisphere of Venus and extends from 50° to 75° N. and from 0° to 60° E. In a regional context, this territory represents a large region of tessera terrain [1] that includes the major portion of Fortuna Tessera in the northern half of the map area and Laima Tessera in the SE corner of the quadrangle. The tessera regions are separated by two deformational belts, Sigrun-Manto Fossae and Ausra Dorsa, each characterized by different tectonic styles. The highest mountain belt on Venus, Maxwell Montes, characterizes the western edge of the quadrangle. Two basin-like features flank Maxwell from the south and north and contain unusual corona-like structures. Highly deformed Maxwell Montes, tesserae, and the deformational belts coincide with regions of high topography surrounded by broad low-lying areas, Sedna Planitia to the southwest , Snegurochka Planitia to the north, and Audra Planitia to the east. Mildly deformed plains materials cover the surface of the Planitiae. The set of specific geologic/topographic features within the V-2 quadrangle offers the possibility to address several important questions related to the geology of Venus: (1) the timing and processes of crustal thickening/thinning, (2) the nature and origin of tesserae and deformation belts and their relation to crustal thickening processes, (3) mechanisms of emplacement of broad volcanic provinces, (4) the presence or absence of major evolutionary trends of volcanism and tectonics, and (5) similarities to and difference from te Archean of Earth. Topographic characteristics: The topographic differences within the quadrangle may reflect variations of the crustal thickness [2]. The most prominent topography in the region corresponds to the broad highlands of Ishtar Terra that in the V-2 quadrangle consists of the vast expanse of Fortuna Tessera and the major mountain belt of Maxwell Montes. These topographic elements of the map area clearly represent large domains of thickened crust [3-6]. In the western portion of Fortuna, its structures broadly wrap around the eastern edge of Maxwell Montes. Topographically the tessera consists of two distinctive parts. The western part resembles a shoulder-like feature, which is about 2 km higher than the eastern part of the tessera. A broad depression separates western and eastern Fortuna. This may indicate that the eastern domain is more related to Laima and Meskhent Tesserae than to the Maxwell-dominated western domain. Topographically, Laima Tessera is similar to the eastern part of Fortuna and also …