block tectonics on Venus p a u l b y r n e r i c h a r d g h a i l a. m. c e l â l s e n g ö r c h r i s t i a n k l i m c z a k r e b e c c a h a h n s e a n s o l o m o n VEXAG meeting #15 byrne et al. 2017.11.15 1
we have long known Venus is a tectonic world byrne et al. 2017.11.15 2
the planet hosts deformation belts and ridge belts Vaidilute Rupes positive-relief landform broad arch smaller-wavelength ridges constant strike for 100s km result of crustal shortening ASTKHIK PLANUM 100 km byrne et al. 2017.11.15 3
as well as groove belts unnamed groove belt negative-relief landforms sub-parallel normal faults evidence for fault linkage result of crustal extension 50 km byrne et al. 2017.11.15 4
Venus hosts many low-lying, belt-bound plains example 1 147 E, 25 S 1,200 km east west 770 km north south heavily tectonized margins BONA CORONA O CONNOR ARTEMIS CORONA MAYAUEL CORONA 500 km byrne et al. 2017.11.15 5
Venus hosts many low-lying, belt-bound plains example 1 147 E, 25 S 1,200 km east west 770 km north south heavily tectonized margins (relatively) undeformed interior BONA CORONA O CONNOR ARTEMIS CORONA MAYAUEL CORONA 500 km 2.5 5.8 km byrne et al. 2017.11.15 6
Venus hosts many low-lying, belt-bound plains example 1 147 E, 25 S 1,200 km east west 770 km north south heavily tectonized margins (relatively) undeformed interior parallel sets of wrinkle ridges 50 km byrne et al. 2017.11.15 7
Venus hosts many low-lying, belt-bound plains example 2 347 E, 42 S 200 km east west 135 km north south 100 km byrne et al. 2017.11.15 8
Venus hosts many low-lying, belt-bound plains example 2 347 E, 42 S 200 km east west 135 km north south elevated margins 100 km 0.8 0.6 km byrne et al. 2017.11.15 9
Venus hosts many low-lying, belt-bound plains example 2 347 E, 42 S 200 km east west 135 km north south elevated margins evidence for lateral shear 100 km byrne et al. 2017.11.15 10
many of these belts show evidence for lateral shear unnamed ridge belt 343 E, 48 S strikes NE sigmoidal ridges proximal curved lineations sinistral (left-lateral) transpression 50 km byrne et al. 2017.11.15 11
many of these belts show evidence for lateral shear Tellervo Chasma 128 E, 58 S strikes NE sigmoidal graben proximal curved lineations dextral (right-lateral) transtension 100 km byrne et al. 2017.11.15 12
leading to low-lying plains with strike-slip margins example 2 347 E, 42 S 200 km east west 135 km north south elevated margins evidence for lateral shear 100 km byrne et al. 2017.11.15 13
this deformation also appears to post-date plains emplacement example 2 347 E, 42 S 200 km east west 135 km north south elevated margins evidence for lateral shear structures superpose plains deposits 50 km byrne et al. 2017.11.15 14
we see something like this type of deformation on Earth Sichuan Basin, China 106 E, 30 S 480 km east west 310 km north south elevated margins 200 km byrne et al. 2017.11.15 15
we see something like this type of deformation on Earth Tarim Basin, China 83 E, 40 S 980 km east west 460 km north south elevated margins evidence for lateral shear 400 km byrne et al. 2017.11.15 16
we see something like this type of deformation on Earth Tarim Basin, China 83 E, 40 S 980 km east west 460 km north south elevated margins evidence for lateral shear 400 km byrne et al. 2017.11.15 17
regionally, Venus has networks of ridge/groove belts Lavinia Planitia 347 E, 47 S multiple, intersecting ridge belts MOLPADIA LINEA 500 km byrne et al. 2017.11.15 18
regionally, Venus has networks of ridge/groove belts Lavinia Planitia 347 E, 47 S multiple, intersecting ridge belts delineate low-lying plains MOLPADIA LINEA 500 km 1.2 1.3 km byrne et al. 2017.11.15 19
that feature widespread evidence for lateral motion Lavinia Planitia 347 E, 47 S multiple, intersecting ridge belts delineate low-lying plains evidence for strike-slip motion MOLPADIA LINEA 500 km byrne et al. 2017.11.15 20
that feature widespread evidence for lateral motion Lavinia Planitia 347 E, 47 S multiple, intersecting ridge belts delineate low-lying plains evidence for strike-slip motion MOLPADIA LINEA 500 km Fernández et al. (2010) byrne et al. 2017.11.15 21
that feature widespread evidence for lateral motion Lavinia Planitia 347 E, 47 S multiple, intersecting ridge belts delineate low-lying plains evidence for strike-slip motion MOLPADIA LINEA 500 km Fernández et al. (2010) byrne et al. 2017.11.15 22
that feature widespread evidence for lateral motion Lavinia Planitia 347 E, 47 S multiple, intersecting ridge belts delineate low-lying plains evidence for strike-slip motion MOLPADIA LINEA 500 km Koenig and Aydin (2010) byrne et al. 2017.11.15 23
these networks are distributed across the planet 3 12 km byrne et al. 2017.11.15 24
of which many are situated in geoid lows 66 152 m byrne et al. 2017.11.15 25
what could be driving lateral motion on Venus? Venus may experience subcrustal lid rejuvenation high surface T leads to weak detachment at shallow crustal depths ( 15 km) Venus crust is thus partly mechanically decoupled from the upper mantle portions of the crust could therefore be relatively free to move Ghail (2015) byrne et al. 2017.11.15 26
what we can say so far numerous narrow bands of tectonic deformation bound low-lying plains on Venus these plains have relatively little interior deformation and may demarcate fault-bound crustal blocks many of the belts show evidence for strike-slip faulting these crustal blocks thus appear to have been translated and rotated, akin to continental lithosphere in China byrne et al. 2017.11.15 27
and what we have yet to answer how are these belts kinematically related? how much strain do they accommodate and how far have these blocks moved and/or rotated? how does this deformation relate (if at all) to the geoid? when did this deformation occur? byrne et al. 2017.11.15 28