 Devana Chasma, middle.Theia Mons, a major shield volcano, is at the bottom left | |
| Coordinates | 22°00′N183°30′E / 22°N 183.5°E /22; 183.5 |
|---|---|
| Diameter | 2000 km |
| Eponym | Devana |
Devana Chasma is a weak extensionalrift zone onVenus, with a length of 4000 km, a width of 150–250 km, and a depth reaching 5 km. Most of the faults are facing north–south. The rift is located inBeta Regio, a 3000 km rise created by volcanic activity. Mantle plumes rising from the bottom are the reason behind the formation of the rift zone. The slow extension rates in the rift may be driven by the same reason.[1][2][3]
General history of the region[1]The formation of the region went through different events with time:
Rift zones are features that related to volcanoes in general andshield volcanoes specially, this feature consists of linear opening in the ground where the lava can spread from the side of the volcano not only from the summit. Repeated eruptions causes more lava to come and activate the rift zone which causes the extension of the crust.[4]
The Devana Chasma formed along theBeta Regio andPhoebe Regio volcanic rises,[5] these different volcanic highlands formed due different mantle plumes. These extensional faults are 4000 km long and can be divided to two main parts, the northern part which covers around 700 km betweenTheia Mons andRhea Mons[6] which formed viaBeta Regio mantle plume. The southern part cover the rest and formed duePhoebe Regio mantle plume. Arecibo radar images and Magellan spacecraft helped in studying theBeta Regio region and shading the light on the Devana Chasma rift system.[2][3]
The lack of erosion and deformation processes record the history and development ofVenus.[7] Evidences from the images of theBeta Regio shows the history behind the region, the rise of the region is caused by an uplift of the mantle plume, which caused the formation ofTheia Monsshield volcano. The Devana Chasma rift system were also constructed by the uplift, and became active due to the Theia Mons volcano. Furthermore, these evidences proposed several aspects concerning the development and history of the rift zone. Nowadays, the rift zone is still active but the rifting is much slower because of the relative cold mantle plume. In previous centuries, the mantle plumes were hotter and the rifting rate were faster, but the mantle got colder and that consistent with the current cold plate of Venus.[7][8]
Due to the similarities between Earth and Venus, it is suggested that they have a similar lithospheric elastic thickness of ~30 km.East African Rift is the only rift that can be compared to Devana Chasma.[9] Both rifts have fault segments length around ~100 km, which makes them stronger than any extensional system onEarth.[10] However, they differ in theirhalf grabens,East African Rifts'half grabens are around 50 km wide while onVenus it is around 150 km. InEast African Rift, the higherelastic thickness can explain the widehalf grabens. However, onVenus the main force is the highshear stress due to the coldlithosphere, which require the faults to be stronger in order to move. As a result, it has a widerhalf grabens than the one on Earth.[7][10] Studying and comparing these two rift systems help us to understand how volcanism and tectonic activities affected the development and formation of theBeta Regio region onVenus.[11][12]
