A New View of the Stratigraphic History of Venus

Guest, J. E.; Stofan, E. R.

doi:10.1006/icar.1999.6091

Cited by 138 publications

(136 citation statements)

References 47 publications

Supporting

Mentioning

128

Contrasting

Unclassified

Order By: Relevance

“…CSPF are generally overlain by small volcanic structures ( Figure 3) and we believe there are few, if any, good examples in our study area of deformation of small volcanic structures by CSPF. This is in contrast to Guest and Stofan [1999] who interpret some small edifices in this region as being cut by fractures. However, some later sinuous lineaments that seem to be controlled in their morphology by the preexisting CSPF do appear to postdate small-scale volcanism (Figure 3).…”

Section: Age Relationscontrasting

confidence: 76%

Experimental and theoretical fracture mechanics applied to fracture of the crust of Venus

et al. 2004

View full text Add to dashboard Cite

[1] Mapping of closely spaced, parallel extensional fractures in the Guinevere and Sedna Planitia regions of Venus reveals a concentric pattern of fractures around the edge of the large topographic rise of Western Eistla Regio. We have constructed 13 transects through these closely spaced parallel fractures (CSPF) and find a mean spacing of between 0.8 and 1.2 km. A two-dimensional, nonlayered, fracture mechanics computer model for the formation of CSPF is described. For cracks extended by a remote tensile stress the stress intensity factor controls the depth of penetration, which in turn, governs the spacing between adjacent cracks based upon the stress-shadow principle. The stress required to initiate cracks depends upon the strength of the material; thus spacing of CSPF depends only on the physical properties of the preexisting rock mass. Using a new fracture mechanics apparatus designed to simulate Venusian conditions (90 bar CO 2 , 450°C) the fracture toughness of basalt was measured for confining pressures up to 20 MPa and for temperature up to 600°C. Fracture toughness was found to increase from $2.4 MPam 1/2 at ambient pressure to $3.0 MPam 1/2 at 10 MPa confining pressure. Fracture toughness showed no clear trend with temperature. The experimental results for fracture toughness suggest that the preexisting rock mass that fits best with observations contains an inverse square distribution of flaws with maximum sizes of only $20-80 cm and that a remote tensile stress of $3-6 MPa is required to form the observed CSPF.

show abstract

Section: Age Relationscontrasting

confidence: 76%

Experimental and theoretical fracture mechanics applied to fracture of the crust of Venus

et al. 2004

View full text Add to dashboard Cite

show abstract

“…In the map area, we find no evidence to support a directional geologic history of Venus (Basilevsky and Head, 1995;Guest and Stofan, 1999). The directional model predicts that specific types of geologic units (coronae, small edifices) formed at distinct time periods Head, 1995, 1998).…”

Section: Geologic Historycontrasting

confidence: 59%

Geologic map of the Themis Regio quadrangle (V-53), Venus

Stofan¹,

Brian²

2012

Scientific Investigations Map

Self Cite

View full text Add to dashboard Cite

“…In the sense of volcanism, it was a directional change from a rather high-rate (although in a net sense not essentially higher than the recent mid-ocean ridge basaltic volcanism of Earth) plains-forming¯oods forming units of global lateral extent to more localized¯oods and formation of large volcanoes with a signi®cantly lower net rate. It is necessary to emphasize that on the background of this large-scale directionalism there are smaller-scale¯uctu-ations which locally may give the impression of a nondirectional fashion of operation of geologic processes (e.g., Guest and Stofan, 1999). For example, the Magellan images show not only young post-Pwr rift zones (our unit RT) but some pre-Pwr rifts too (our unit FB, sometimes part of Pdf).…”

Section: Discussionmentioning

confidence: 97%

“…In the comparable time period, Venus shows no certain signature of plate tectonics, particularly in post-tessera time, and the density of deformational structures and probably the strain rate (Grimm, 1994) were de®nitely declining with time. In the observed part of the geologic history of Venus, its global tectonic environment passed from an initial dominance of contraction, through extension, then again contraction, and ®nally extension thus showing a directional style of evolution of Venus, in contrast to a non-directional style (e.g., Guest and Stofan, 1999).…”

Section: Discussionmentioning

confidence: 99%