2025-09-16 カリフォルニア大学サンディエゴ校（UCSD）
Web要約 の発言：
Coronae marked in dark green pock Venus’ surface amid larger and taller rises marked in orange. Image: Venus Quickmaps
＜関連情報＞
- https://today.ucsd.edu/story/an-explanation-for-the-look-of-venus-mysterious-surface
- https://www.pnas.org/doi/10.1073/pnas.2504491122
金星におけるガラス天井対流領域とコロナの起源・多様性 The glass-ceiling convective regime and the origin and diversity of coronae on Venus
Madeleine C. Kerr, Dave R. Stegman, Suzanne E. Smrekar, and Andrea C. Adams
Proceedings of the National Academy of Sciences Published:September 16, 2025
DOI:https://doi.org/10.1073/pnas.2504491122
Significance
Venus and Earth are considered to be “twin” planets, sharing roughly the same size, bulk density, and distance from the Sun. Despite our lacking substantial data of Venus’s interior, the planets’ surfaces indicate that they diverged substantially in their evolution. The presence of coronae features on Venus—in contrast to their absence on Earth—is a fundamental mystery in planetary science. This study explains a possible process for how convection in Venus’s mantle can produce small-scale upwellings (~60 to 1,000 km) which generate many coronae, large scale upwellings (~2,000 km) which generate the large volcanic rises, and the observed surface dynamic topography. The presence of the mineral phase transitions underpinning these dynamics argues for a mantle temperature over 200 K hotter than Earth’s.
Abstract
Venus and Earth are rocky planets of roughly the same size and bulk density, yet their surface volcanic and tectonic features appear substantially different. On Venus, the coexistence of large volcanic highlands—interpreted as the surface expression of long-lived mantle plumes—alongside coronae, smaller features thought to be caused by transient thermal diapirs, remains enigmatic. Using two-dimensional numerical models of mantle convection with sharp and broad mineral phase transitions for pyrolite, we show that both scales of upwellings can be generated in a stagnant lid planet with an interior temperature 250 to 400 K warmer than Earth’s. The smaller plumes originate from a ~600 km deep internal layer that exists as a consequence of the different sequence of mineral phase transitions that occur in warmer mantles less processed and differentiated by partial melting and volcanism. Future models that include melting will provide further tests of our hypothesis.
