CHARACTERISTICS OF IMPACT CRATERS IN THE MAHUEA THOLUS QUADRANGLE (V-49), VENUS

The Mahuea Tholus quadrangle (V-49), Venus, extends from 25-50°S and 150-180°E and encompasses approximately 6,500,000 km². The quadrangle has largely been affected by volcanic and tectonic processes, but also contains 13 confirmed impact craters (Table 1), which accounts for ~1% of the total number of craters on Venus; 12 of the craters occur entirely within V-49 and one crater, Austen, straddles the boundary between V-49 and V-37 to the north. In addition to impact structures, at least four radar dark circular splotches that do not host an impact crater occur within V-49. We interpret these splotches as the result of air burst events that did not create a crater structure; two of these splotches (splotches A and B) are spatially associated with Qarlygha and Kaikilani impact craters and may be tied to their occurrence. Impact craters range from 12-100 km in diameter with an average diameter of ~20 km. All craters are associated with ejecta blankets and at least three craters – Howe, Onissya, and Valadon – also host fluidized ejecta materials. Onissya appears to represent a possible double crater. Located east of Howe, and potentially associated with its formation, is a radar-bright, ‘streaky’ patch that could be either ejecta or additional fluidized material. Seven craters exhibit radar-dark floors. Five craters exhibit a central peak and the occurrence of a central peak is indeterminate for five craters (in Table 1). Ten craters appear to have occurred after tectonism within V-49 and the remaining three craters have been deformed by wrinkle ridges and fractures meaning they predate at least some tectonic activity in V-49. Future work will further attempt to constrain crater stratigraphy within V-49.

Table 1. Impact features of V-49

Crater name	Latitude (deg N.)	Longitude (deg E.)	Diameter (km)	Halo	Central Peak	Deformation
Austen	-25	168.4	45.1	N	Y	Y
Ayana	-29.2	175.5	13.8	Y	?	N
Howe	-45.7	174.8	38.6	Y	Y	N
Kaikilani	-32.8	163.2	19.9	Y	Y	N
Onissya	-25.6	150.2	8.2	Y	N	N
Pavlinka	-25.5	158.7	7.5	N	N	Y
Philomena	-40.7	151.9	14.8	Y	?	N
Qarlygha	-33	162.9	9.3	Y	N	N
Radhika	-30.3	166.4	7.9	Y	N	N
Whitney	-30.2	151.3	42.5	N	Y	Y
Ulpu	-35.7	179	7	Y	?	N
Valadon	-49	167.7	25.2	Y	Y	N
Yasuko	-26.1	169	10.6	Y	?	N
Zemfira	-46.2	157.7	11.4	Y	?	N
Splotch A	-33.3	161.9	38.1
Splotch B	-33.4	162.8	19.5
Splotch C	-36.4	162.5	61.9
Splotch D	-41.7	158.2	52.9