Tag: geology

Hadean Oceans

Oceans formed far more quickly than expected:

The Hadean eon, following the global-scale melting of the mantle, is expected to be a dynamic period, during which Earth experienced vastly different conditions. Geologic records, however, suggest that the surface environment of Earth was already similar to the present by the middle of the Hadean. Under what conditions a harsh surface environment could turn into a habitable one remains uncertain. Here we show that a hydrated mantle with small-scale chemical heterogeneity, created as a result of magma ocean solidification, is the key to ocean formation, the onset of plate tectonics and the rapid removal of greenhouse gases, which are all essential to create a habitable environment on terrestrial planets. When the mantle is wet and dominated by high-magnesium pyroxenites, the removal of carbon dioxide from the atmosphere is expected to be more than ten times faster than the case of a pyrolytic homogeneous mantle and could be completed within  160 ma. Such a chemically heterogeneous mantle would also produce oceanic crust rich in olivine, which is reactive with ocean water and promotes serpentinization. Therefore, conditions similar to the Lost City hydrothermal field may have existed globally in the Hadean seafloor.

Underworld Continents

Giant blobs nestled deep in the Earth may influence everything from the structure of island chains to mass-extinction events. If buoyed to the surface, they would be hot enough to cause gigantic, sustained eruptions. In turn, that volcanism could have changed the climate and even led to mass extinctions. Such a sequence, if verified, would be the ultimate antediluvian time bomb — apocalyptic extinctions triggered by subterranean structures buried since the birth of the world.

Fiber topography

Spotting an undersea fault using fiber-optic cables

He and his team had disconnected the cable from all its usual sensors so they could use the fiber itself to sense vibrations on the ocean floor. By monitoring how light beamed and bounced through the transparent fiber, Lindsey’s team was able to describe the texture and topography of the earth it was buried in

Earthquake Prediction

The finding had big potential implications. For decades, would-be earthquake prognosticators had keyed in on foreshocks and other isolated seismic events. The Los Alamos result suggested that everyone had been looking in the wrong place — that the key to prediction lay instead in the more subtle information broadcast during the relatively calm periods between the big seismic events.

Mars Geology

This week’s map is an artistic rendition of the geologic map of Mars designed by the USGS. I used the same geology data as the original map, but I added more topographic and label data, redesigned the visual style, and also edited the key for a more general audience. One of the most difficult parts of making this map was translating the key into plain English. The original USGS map was designed for geologists, so I had to look up almost all of the vocabulary. For example, my abbreviated definition for a caldera rim was “The rim of an empty magma chamber left behind after a volcanic eruption.” The original description was “Ovoid scarp, outlines single or multiple coalesced partial to fully enclosed depression(s); volcanic collapse, related to effusive and possibly explosive eruptions.”

Underwater Pareidolia

They believe the structures began forming as early as 5M years ago, when a hidden rupture in the seabed sent methane and other gases bubbling upward. Microbes living in underwater sediment devoured the carbon in these gases, instigating a chemical process that gave the mud the consistency of cement. Hard columns formed around the gas seeps, and marine creatures boring into the sediment gave rise to other strange “doughnut” shapes

sometimes strangely geometric shapes have an entirely natural explanation