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DETAILED MAPPING OF GRABENS IN A CORONA-RICH PORTION OF DALI CHASMA, 1000 KM SW
OF ATLA REGIO, VENUS. A. Hasanaine1, H. El Bilali2,3, R.E. Ernst2,3, N. Youbi1 1Department of Geology,
Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakesh, Morocco; rziki.23kech@gmail.com, 2Department
of Earth Sciences, Carleton University, Ottawa, Ontario, Canada; hafidaelbilali@cunet.carleton.ca;
richard.ernst@ernstgeosciences.com, 3Faculty of Geology and Geography, Tomsk State University, Tomsk, Russia;
Introduction: Although, corona can be abundant
along chasma (rifts) (e.g. [1-6]), the role of corona in the
evolution of chasma is not well understood. The present
contribution is a detailed (1:500,000 scale) geological
mapping of a section of this about 1000 km to the SW
of Atla Regio (Fig. 1). The mapping will graben
systems (interpreted to overlie dykes), normal faults
associated with rifting, and associated flows, all
integrated with topographic data. Herein we report on
progress in mapping graben systems.
The goal of this high resolution (1:500,000 scale
mapping) is an improved understanding of the
relationships between corona and rift segments, and in
particular to test the model of [6]. Based on detailed
mapping of graben fissure systems and interpreted rift
faults along a 1500 km long segment of Parga Chasma,
[6] recognized that many coronae represent the locus of
local triple junction rift centres, and extrapolated this
observation to the entire length of both Parga and
Hecate Chasmata.
Mapping Results: We have mapped 12,800
extensional lineaments (Fig. 2) and these have been
generalized and grouped into multiple systems based on
trend and geometry (radiating, circumferential and
linear) (Fig. 3).
For instance, in the lower left of the image, there is
centre 1 (Flidais Corona) which has both a yellow
arcuate swarm (part of a circumferential swarm) and a
radiating swarm (orangish yellow). Centre 2 also has
both radiating (orangish yellow) and circumferential
(green) swarms. Centre 3 has partial radiating (yellow
to the north) and partial circumferential (pink on the
north side) swarms. Centres 4-7 each have
circumferential swarms. Centre 8 has a radiating
swarm. In addition, there are major linear swarms,
notably the NE trending red set (labelled A).
Many of these radiating and circumferential graben
systems likely overlie dyke swarms [7,8], and therefore,
are important igneous component of their magmatic
centres. In addition, those major linear swarms that are
also overlying dykes (and not purely rift related) would
represent major dyke swarms belonging to more distal
magmatic centres, potentially up to more than 1000 km
away [7,8]
Future Work: After further work on generalizing
the graben systems and linking them to magmatic
centres, the next step will be assessing the age
relationships of the centres, through the cross-cutting
relationships of their graben systems.
Another important component of this research will
be detailed (1:500,000 scale) mapping of the flows and
integration of the flow relationships with the framework
built from the graben relationships.
The result will be a detailed and integrated
understanding of the magmatic and tectonic history of
this corona-rich portion of Dali Chasma.
References: [1] Hamilton, V.E., Stofan, E.R. (1996)
Icarus, 121, 171–194. [2] Martin, P., Stofan, E.R.
(2004). 35th LPSC, Abstract # 1576. [3] Martin, P., et
al. (2007). JGR, 112, E04S03. [4] Smrekar, S.E., et al.
(2010). 115, E07010. [5] Ivanov, M.A., Head, J.W.
(2015). Planet. Space Sci., 113-114, 10-32. [6] Graff,
J.R., et al. (2018). Icarus, 306, 122-138. [7] Grosfils
E.B., and Head J.W. (1994) GRL, 21, 701–704. [8]
Buchan K.L. and Ernst R.E. (2021) Gond. Res., 100, 25-
43. [9] Christensen P. R. et al. (2009) AGU Fall
Meeting, Abstract #IN22A-06.
Figure 1. Location of study area. Named Coronae:
A = Atahensik, F = Flidais, K = Khabuchi, N =
Nirmali, S = Sith, Z = Zemina. H = Henwen Fluctus, V-
D = Vibert-Douglas Patera, V = Vilakh Tholus, K-E =
Khotal-Ekva Tholi. Background Magellan SAR image
from JMARS [9].
1926.pdf53rd Lunar and Planetary Science Conference (2022)
Figure 2. Detailed mapping of grabens (12,800 lineaments mapped). Stars locate inferred magmatic centres,
many associated with circumferential grabens and therefore likely corona.
Figure 3. Generalized distribution of grabens grouped into distinct sets distinguished by colour. Labels are linked
to the discussion in the text.
1926.pdf53rd Lunar and Planetary Science Conference (2022)