The Earth Story

blackjackjosh

The beginning of Yellowstone, some crazy views

Abyssal Plains that aren’t so plain.

Abyssal plains cover around a third of the whole planet, about as much as dry land combined. Off the coast of northwest Africa, the flat plain of mud and sand has the marks of a cataclysmic event way back in history. A submarine flow that happened about 60,000 years ago deposited sand and mud on the ocean floor. That flow, an underwater sand storm was on a scale that’s hard to imagine. In just a few hours, it moved more sediment than all the rivers of the world carry in a year.

It started as a landslide from a deep canyon running off shore from North Africa. As the landslide started to disintegrate, all the sediment started to churn up, mix in seawater and then made its way down the canyon. The flow then came out of the canyon and started to spread over an area about 161kilometers (100miles) wide. At 20 meters a second, it raced over a plain flatter than a pool table and it travelled over 1500 kilometres (932 miles), eventually stopping on the flanks of the Mid-Atlantic ridge. This happened a long time ago, but even today events like this happen but they are hidden under 3-5 kilometres (1.9-3.1 miles) of water.

Pitch black and under crushing pressure the abyssal plain is hard to explore, but each time we descend to these depths we find something new and unexpected. Mud volcanoes are an example; hot gas escaping from under the seabed liquefies the sediment then builds them up to form mud sculptures. There are mud volcanoes on land such as in southern California where heat deep below ground level liquefies the mud.

Mud volcanoes are not very common on dry land but on the abyssal plain there are more than 100,000 across the globe, and much bigger. The ones in southern California are only a meter or so in height (check out the short video and look at how awesome they are and soothing they sound), but beneath the Gulf of Cadiz off southern Spain, there are mud volcanoes that have grown to enormous sizes. This field of giant mud volcanoes has only recently been mapped, nearly 300 meters high and 5 kilometres across.

It's not just mud that oozes up onto the abyssal plain. In some places, asphalt (tar), emerges onto the ocean floor. As soon as it meets the cold water the asphalt solidifies over large areas like a road running over the abyssal plain. There are a few places on land where tar bubbles up like this. The most well known is right in the middle of Los Angeles, the La Brea tar pits. This place is famous for the North American animals now extinct that were trapped in the tar yet, when they died were preserved intact.

On land this tar was a death trap but under water they form oasis of life on the abyssal plain. Bacteria live off chemicals in the tar like the bacteria on hydrothermal vents. Other creatures feed on these bacteria creating rich thriving communities. As well as tar, other chemicals seep up off the ocean floor, and everywhere this happens life takes advantage of it.

Humans have only explored a small fraction of these vast areas. There must be many more creatures just waiting to be discovered in the deep depths of the ocean.

~ JM Photo Credit: http://bit.ly/1xykw9z

http://bit.ly/1xf6xLh

More Info: Abyssal Plains: http://bit.ly/1x1bLKb

Mud Volcano, California: http://abt.cm/1F429RK

Video: Mud Volcano: http://bit.ly/1O6GuuB

Video: Underwater Asphalt: http://bit.ly/1AFL0qI

La Brea tar pits: http://bit.ly/Ze6z5T

Tectonics and mud volcano development in the Gulf of Cádiz Marine Geology, Volume 261, Issue 1, Pages 48-63 T. Medialdea, L. Somoza, L.M. Pinheiro, M.C. Fernández-Puga, J.T. Vázquez, R. León, M.K. Ivanov, V. Magalhaes, V. Díaz-del-Río, R. Vegas

Iceland travel clip including mud volcano, fumarole/former mud volcano, multi-tiered waterfall and rapids, flowers, and view over the sea cliff towards the Atlantic.

Mud volcano erupting in Azerbaijan

Here a photographer has caught a mud volcano literally in the act; spurting mud upward into the air.

A mud volcano is a place on the Earth where a mixture of water, gases, and mud pours out from beneath. As mud dries, it will solidify, so mud volcanoes often build cones around them that resemble the shapes made by solidifying lava on the slopes of volcanic cones, even if the ones around mud volcanoes are smaller.

For a mud volcano to occur, a couple conditions must be present. There must be mud, mixed with water, and there must be some pressure gradient that drives the mud up to the surface through a crack. These conditions can be met in areas that are hydrothermally active, as occur in Yellowstone, or in areas that are full of gassy hydrocarbons like Azerbaijan.

Azerbaijan hosts several hundred mud volcanoes, more than any other country in the world. The mixture of mud and water is carried to the surface as natural gas leaks out from below; effectively marking the locations of some of the country’s gas fields. Some of these leaks will constantly stay on fire; others will actually explode on occasion.

-JBB

Image credit: http://commons.wikimedia.org/wiki/File:Bubbling_Mud_Volcano_(3860838997).jpg

Read more: http://www.atlasobscura.com/places/mud-volcanoes-of-azerbaijan http://www.volcanodiscovery.com/azerbaijan/mud-volcanoes.html

Ooh neat, underwater mud volcano

Slow motion mud volcano

Were mud volcanoes the first habitat?

Many solutions have been offered over the years to the puzzling problem of the geological environment in which rock and chemistry somehow turned into life. They include between layers within clays in altered volcanic rocks and black/white smokers deep under the ocean surface (see http://tinyurl.com/o99wjxv). A study from the French CNRS published last year in the Proceedings of the National Academy of Sciences advances mud volcanoes (see[http://tinyurl.com/ojo3vov) as another possible location.

Geochemical analysis of highly metamorphosed Archaean eon (2-2.5 billion years ago) mud volcanoes in a rock called the Issua Gneiss that outcrops in Greenland has revealed that they released chemical elements essential to the formation of early biomolecules 3.8 billion years ago, and that the chemical environment was favourable to life's emergence back in that misty epoch.

The crucial mineral in this case is serpentine (a green mineral often used to imitate jade), originally formed when seawater in giant convection cells infiltrates the upper mantle through the extensively fractured young oceanic crust, or is carried down on a subducting slab. The mineral is also precipitated in hot springs and veins of hydrothermal origin. They used zinc isotopes to indicate whether the environment of the fluids that permeated the serpentinites was acidic or alkaline. Alkaline environments are much more favourable to the development of stable biomolecules such as amino acids, and the Issua serpentine was clearly permeated by carbonate rich alkaline fluids. Black smokers are less likely as a source of life as they are quite acidic, while white smokers are slightly alkaline and another strong contender.

The zinc signature is similar to that of serpentine mud volcanoes in the Marianas trench rather that from oceanic spreading ridges where black and white smokers occur. It is the first time that an environment suitable for life has been proved in such ancient rocks. Such mud volcanoes are rarer now, since they congregate seemingly in places where one oceanic plate dives under another back into the mantle. Back in the Archaean, the continental crust was much smaller than today's, which has been built up by continental collisions and subduction volcanism over the past several billion years. This would have meant more oceanic crust, and possibly a greater number of life nurturing mud volcanoes.

Loz

Image of mud volcano in Azerbaijan credit: Rietje

http://www.livescience.com/16580-mud-volcanoes-life-ingredients-greenland.html

Abstract: http://www.pnas.org/content/early/2011/10/10/1108061108.abstract

Original paper, paywall access: http://www.pnas.org/content/early/2011/10/10/1108061108.abstract

I like the ones that just kinda plop down next to the geothermal feature. Original caption: