Global tectonic evolution of Venus, from exogenic to endogenic over time, and implications for early Earth processes

Hansen, Vicki L.

doi:10.1098/rsta.2017.0412

Cited by 31 publications

(19 citation statements)

References 135 publications

(248 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We estimated model‐predicted topography from the normal stresses at the surface. Without ACPs, the predicted topography range is mostly within [−1, 1] km and thus broadly representative of Venus' lowland and mesoland (Hansen, 2018), but no large‐scale highlands were observed. During overturn episodes, the predicted range is typically broader, especially due to up to 5 km deep trenches forming at the major recycling sites, which are not seen on present' Venus, but pronounced highland regions are still not observed.…”

Section: Discussionmentioning

confidence: 99%

“…The ACPs therefore correlate with topography lows in our model, which seems unrealistic compared to Venus' crustal highlands. Reducing their intrinsic density in future models should result in their uplift and a topography comparable to Venus' highlands, where also many (not all) of the planets' tesserae are hosted (see, e.g., Hansen, 2018).…”

Section: 1029/2019je006340mentioning

confidence: 99%

See 1 more Smart Citation

Implications of Anomalous Crustal Provinces for Venus' Resurfacing History

et al. 2020

View full text Add to dashboard Cite

Current Venus tectonics suggests a stagnant lid mode of mantle convection. However, the planet is debated to enter an episodic regime after long quiescent periods, driven by resurfacing due to rapid subduction and global crustal recycling. Tessera regions that cover approximately 10% of Venus' surface appear to be strongly deformed, which suggests that they have survived at least the latest resurfacing event, although the composition and age of the tesserae are unknown. Based on mantle convection modeling, we studied the effects of anomalous crustal provinces (ACPs) on mantle dynamics and postoverturn lithospheric survival. As a hypothesis, we assume ACPs to be thick, compositionally anomalous, and rheologically strong units, similar to terrestrial cratons. We model Venus with a varying number of preimposed ACP units and differing lithospheric yield stress in 2-D and 3-D spherical geometry. The impact of ACPs on mantle dynamics and the survival of lithosphere is investigated by examining the thermal evolution, crustal thickness, and surface age distribution. We find that the number and timing of overturns are highly dependent on the yield stress and, to some degree, on the number and size of the preimposed ACPs. ACPs in particular affect the wavelength of convection and may foster the survival of lithosphere even of those portions not being part of an ACP. However, ACPs do not seem to be a good analog for tessera regions due to their exaggerated age and (likely) thickness, but-with appropriate density contrast-may be more useful representatives of Venus' highland plateaus. Plain Language Summary Plate tectonics shapes the Earth's surface but is currently probably not active on Venus. Instead, periods with a more mobile Venusian surface remain possible, in particular because the surface is rather young. Episodic resurfacing events-known as overturns-during which much of the surface is recycled into the planetary interior may explain this. However, about 10% of Venus' surface are covered by tesserae, strongly deformed and possibly older-than-average regions that may have survived overturns. The origin of such anomalous crustal provinces (ACPs) is unknown, but we hypothesize them to be similar to the cratonic keels of Earth's continental crust. We investigate how ACPs affect the interior dynamics and resurfacing history and whether they promote the (partial) survival of the surface during overturns. We find that both the presence of ACPs and the strength of the lithosphere alter the overturn frequency. ACPs affect the mantle flow pattern and facilitate survival of non-ACP lithosphere and crust by shielding it from recycling during overturn events. After analyzing our model-predicted distributions of crustal thickness and surface age, however, preexisting ACPs do not seem to be adequate analogues for Venus' tesserae, as their thickness and age appear exaggerated given the observation on Venus' surface.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: 1029/2019je006340mentioning

confidence: 99%

Implications of Anomalous Crustal Provinces for Venus' Resurfacing History

et al. 2020

View full text Add to dashboard Cite

show abstract

“…In summary, the most first‐order observation that emerges from the AMA is the regional coherence of preserved geologic patterns, which provide a variable record of three relatively distinct geologic eras: the ancient era, the Artemis superstructure era, and the youngest fracture zone complex era. The first two eras are also variably recorded within the NMA (Hansen & López, 2018; López & Hansen, 2020a, 2020b); all three eras can be extrapolated to the global scale, although the Artemis era is not strictly global as the Artemis superstructure covers about 30% of the planet surface (Hansen, 2018). Geologic relations captured within the AMA illustrate the spatial and temporal relations of these three eras across time and space as described herein.…”

Section: Discussionmentioning

confidence: 99%

“…Geologic mapping of the AMA and NMA were undertaken in a collaborative project. The 1:10‐M scale of the AMA and NMA is well suited to the large regional scale of Venus geologic domains (Figure 1) (Hansen, 2018; Hansen & López, 2018). A comparatively similar region on Earth would cover numerous tectonic plate boundaries and include both continental and oceanic crust.…”

Section: Introductionmentioning

confidence: 99%

Geologic Map of Aphrodite Map Area (AMA; I‐2476), Venus

Hansen

López

2020

Earth and Space Science

Self Cite

View full text Add to dashboard Cite

We present a 1:10-M-scale geologic map of the Aphrodite Map Area (AMA) of Venus (0°N-57°S/60-80°E). Geologic mapping employed NASA Magellan synthetic aperture radar and altimetry data. The AMA geologic map, with detailed structural elements and geologic units covering over one eighth of Venus' surface, affords an important and unique perspective to test models of global-scale geologic processes through time. Geologic relations record a history inconsistent with global catastrophic resurfacing. The AMA displays a regional coherence of preserved geologic patterns that record three sequential geologic eras: the ancient era, the Artemis superstructure era, and the youngest fracture zone era. The ancient era and Artemis superstructure, with a footprint covering more than 25% of the surface, are recorded in the Niobe Map Area to the north. The latter two eras likely overlap in time. The fracture zone domain, part of a globally extensive province, marks the most spatially focused tectonomagmatic domain within the AMA. Impact craters are both cut by and overprint fracture zone structures. Twelve percent of AMA impact craters that occur within the fracture zone domain predate or formed during fracture zone development. This observation indicates the relative youth of the fracture zone era and is consistent with the possibility that this domain remains geologically active. The AMA records a rich geologic history of large tract of the surface of Venus and provides an important framework to formulate new working hypotheses of Venus evolution and contribute to planning future studies of the surface of planets.

show abstract

“…Venus, which has a younger surface than Earth on average 94 (Fig. 1), could operate in a similar geodynamic regime as an early Earth that featured plume-induced subduction 95 . Enigmatic Venusian tectonic features such as coronae (Box 2) might provide clues to the initiation of plate tectonics on Earth if they are sites of incipient subduction (as indicated by their morphology and correlations between gravity and topography).…”

Section: Initiation Of Plate Tectonicsmentioning

confidence: 99%