نتایج جستجو برای: volcanism
تعداد نتایج: 2423 فیلتر نتایج به سال:
The Early Cretaceous Greater Ontong Java Event in the Pacific Ocean may have covered ca. 1% of the Earth's surface with volcanism. It has puzzled scientists trying to explain its origin by several mechanisms possible on Earth, leading others to propose an extraterrestrial trigger to explain this event. A large oceanic extraterrestrial impact causing such voluminous volcanism may have traces of ...
Crater size–frequency analyses have shown that the largest volcanic plains deposits on Mercury were emplaced around 3.7 Ga, as determined with recent model production function chronologies for impact crater formation on that planet. To test the hypothesis that all major smooth plains on Mercury were emplaced by about that time, we determined crater size–frequency distributions for the nine next...
The Atlas Mountains of Morocco display high topography, no deep crustal root, and regions of localized Cenozoic alkaline volcanism. Previous seismic imaging and geophysical studies have implied a hot mantle upwelling as the source of the volcanism and high elevation. However, the existence, shape, and physical properties of an associated mantle anomaly are debated. Here we use seismic waveform ...
We determined model ages of mare deposits on the farside of the Moon on the basis of the crater frequency distributions in 10-meter-resolution images obtained by the Terrain Camera on SELENE (Selenological and Engineering Explorer) (Kaguya). Most mare volcanism that formed mare deposits on the lunar farside ceased at approximately 3.0 billion years ago, suggesting that mare volcanism on the Moo...
[1] Mars Orbiter Camera images are used to identify widespread material interpreted to have formed via explosive volcanism on Arsia Mons volcano, Mars. This material crops out in cliff sections associated with pit craters in layers 45– 50 m thick. The large range of elevations where the material is found (6.2–17.5 km) suggests locally-derived materials, although extensive reworking has produced...
The possibility of volcanism on Mercury has been a topic of discussion since Mariner 10 returned images of half the planet's surface showing widespread plains material. These plains could be volcanic or lobate crater ejecta. An assessment of the mechanics of the ascent and eruption of magma shows that it is possible to have widespread volcanism, no volcanism on the surface whatsoever, or some r...
Tutuila is a basaltic volcanic island within the east southeasterly trending Samoa Island chain in the Pacific Ocean. Potassium-argon ages on 38 whole rock samples oflavas and intrusives demonstrate that the main period of subaerial volcanism occurred over a relatively short interval of about 0.6 Ma in the Early Pleistocene. The major shield volcano, Pago, was built between about 1.54 and 1.28 ...
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