Geological history of Theia Mons, Beta Regio plume, Venus: Recognition of two main magmatic centers for flows, radiating dyke swarms and triple junction rifting

IF 1.8 4区物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS

Planetary and Space Science Pub Date : 2025-01-27 DOI:10.1016/j.pss.2025.106050

A.S. Shimolina , R.E. Ernst , H. El Bilali , D.G. Malyshev , V.E. Rozhin , E.G. Antropova

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Abstract

Theia Mons (centered at 23.4° N, 79.4° W) is the main volcanic center for the Beta Regio plume, of the Beta-Atla-Themis (BAT) region, Venus. Synthetic aperture radar data (SAR) and altimetry data from the 1989–1994 NASA Magellan mission were used to produce a geological map and history of Theia Mons, revealing two distinct magmatic centers (200 km apart), each the focus of basaltic lava flows, extensional lineaments (representing the surface expression of dyke swarms), and associated rift zones. The study area spans 88°W to 72°W, 16°45′N to 29°45′N, and mapping was at 1:500,000 scale. Our detailed mapping makes this area a prime target for the future Venus missions (orbital and lander), also given that Beta Regio is a strong candidate for ongoing volcanic activity.

Lava (basaltic) flow units (88 distinguished on the basis of variation in radar backscatter) belonging to Theia Mons volcano were combined into 19 Flow Groups and then into 3 Flow Packages. The lava flows appear to diverge from two distinct magmatic centers, labelled Center 1 (24.5°N, 78.1°W) and Center 2 (23.4° N, 79.4°W), with the older Center 1 being obscured by the volcanism of the younger Center 2. Center 1 consists of flows with low radar brightness and which extend to a maximum to 830 km from the center. Center 2 coincides with the currently preserved central caldera and consists of lava flows of low radar brightness with a maximum length of 620 km, followed by a second pulse of radar-bright flows that are less extensive and concentrated near the center.

About 10,000 extensional lineaments (grabens, fissures, and fractures) were mapped and grouped into 19 systems, of which 15 are interpreted to overlie dyke swarms: 2 radiating systems are associated with Centers 1 and 2, and 13 other systems belong to other (older and likely unrelated) magmatic centers in the region. A partial circumferential swarm may also be present, associated with Center 2.

Four other extensional lineaments sets are inferred to represent sets of normal faults associated with rift zones (Devana and Zverine, and additional rift zones). These rift zones exhibit two sets of ‘triple junction’ geometry, which are approximately also focussed on the same Centers 1 and 2, revealed by the lava flows and rift zones.

An underlying mantle plume is interpreted to be responsible for the dykes, flows and triple junction rifting. The cause of the shift between Centers 1 and 2 (200 km to SW) is unknown, but plausible mechanisms include a shift of the lithospheric plate above a stationary single plume, or a bending of the mantle plume (e.g. in a mantle wind) between timing of Center 1 and Center 2 activity.

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来源期刊

Planetary and Space Science 地学天文-天文与天体物理

CiteScore

5.40

自引率

4.20%

发文量

126

审稿时长

15 weeks

期刊介绍： Planetary and Space Science publishes original articles as well as short communications (letters). Ground-based and space-borne instrumentation and laboratory simulation of solar system processes are included. The following fields of planetary and solar system research are covered: • Celestial mechanics, including dynamical evolution of the solar system, gravitational captures and resonances, relativistic effects, tracking and dynamics • Cosmochemistry and origin, including all aspects of the formation and initial physical and chemical evolution of the solar system • Terrestrial planets and satellites, including the physics of the interiors, geology and morphology of the surfaces, tectonics, mineralogy and dating • Outer planets and satellites, including formation and evolution, remote sensing at all wavelengths and in situ measurements • Planetary atmospheres, including formation and evolution, circulation and meteorology, boundary layers, remote sensing and laboratory simulation • Planetary magnetospheres and ionospheres, including origin of magnetic fields, magnetospheric plasma and radiation belts, and their interaction with the sun, the solar wind and satellites • Small bodies, dust and rings, including asteroids, comets and zodiacal light and their interaction with the solar radiation and the solar wind • Exobiology, including origin of life, detection of planetary ecosystems and pre-biological phenomena in the solar system and laboratory simulations • Extrasolar systems, including the detection and/or the detectability of exoplanets and planetary systems, their formation and evolution, the physical and chemical properties of the exoplanets • History of planetary and space research