Geochemical constraints on petrogenic processes on Venus

A volcanic origin for the outflow channels of Mars: Key evidence and major implications

“…Exotic magma compositions have previously been hypothesized as necessary for channel development on Venus (Baker et al, 1992b;Komatsu et al, 1992Komatsu et al, , 1993Kargel et al, 1994;Baker et al, 1997;Treiman, 2009), but the lunar record demonstrates that lavas of mafic composition can have the capacity for voluminous low viscosity flow, substantive vertical and lateral erosion, and extreme lengths for both open and channelized flows (Murase and McBirney, 1970;Hulme, 1973Hulme, , 1974Schaber et al, 1976;Wilhelms, 1987;Leverington and Maxwell, 2004;Leverington, 2006Leverington, , 2009. Venusian channels have not yet been directly visited by spacecraft, but surface compositions measured at the Venera and Vega landing sites are consistent with those expected of dry mafic lavas (e.g., Surkov, 1983;Surkov et al, 1987;Kargel et al, 1993;Fegley et al, 1997;Nikolaeva and Ariskin, 1999). Eruption of low viscosity, lunar-type basalts on Venus would not be unexpected or inconsistent with available geochemical data (Gregg and Greeley, 1993;Gregg, 1996).…”

Themis Regio, Venus: Evidence for recent (?) volcanism from VIRTIS data

“…Given their overall morphology (e.g., , the appearance of venusian plains in Venera lander images ( Garvin et al, 1984 ), and the basaltic composition determined by several plains landers ( Surkov, 1990;Nikolaeva and Ariskin, 1999 ), it can be assumed that the average venusian plains are lava flows that are basaltic in composition. The range of emissivity derived from VIR-TIS data of volcanic features without any indication of non-basaltic composition indicates a significant variability of surface composition ( Mueller et al, 2008 ).…”

Volcanism and volatile recycling on a one‐plate planet: Applications to Venus

“…The wide range of apparent magmatic viscosities demonstrated by these disparate volcanic forms is supported by data from Soviet landers indicating compositional variability in Venusian magmas. Rocks analyzed by the Venera 9 and 10 and Vega 1 and 2 landers have K less than 1 wt% and U less than 1 ppm, while rocks at the Venera 8 landing site have K contents as high as 4 ± 1.2 wt% and U as high as 2.2 ± 0.7 ppm [ Surkov , 1990; Nikolaeva and Ariskin , 1999]. Nikolaeva and Ariskin [1999] suggest that the Venera 8 composition may be the result of melting an eclogite, while the other magmas may be mantle melts.…”

“…Rocks analyzed by the Venera 9 and 10 and Vega 1 and 2 landers have K less than 1 wt% and U less than 1 ppm, while rocks at the Venera 8 landing site have K contents as high as 4 ± 1.2 wt% and U as high as 2.2 ± 0.7 ppm [ Surkov , 1990; Nikolaeva and Ariskin , 1999]. Nikolaeva and Ariskin [1999] suggest that the Venera 8 composition may be the result of melting an eclogite, while the other magmas may be mantle melts. The high alkali content of some Venusian compositions may also be the product of fractionation in magma chambers [ Bazilevsky , 1997].…”