lithospheric

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A Guide to the Energy of the Earth

Energy moves in and out of Earth’s physical systems, and during any energy transfer between them, some energy is lost to the surroundings as heat, light, sound, vibration, or movement.

Our planet’s energy comes from internal and external sources. Geothermal energy from radioactive isotopes and rotational energy from the spinning of the Earth are internal sources of energy, while the Sun is the major external source, driving certain systems, like our weather and our climate.

Sunlight warms the surface and atmosphere in varying amounts, and this causes convection, producing winds and influencing ocean currents. Infrared radiation, radiating out from the warmed surface of the Earth, gets trapped by greenhouse gases and further affects the energy flow.

From the TED-Ed Lesson A guide to the energy of the Earth - Joshua M. Sneideman

Animation by Marc Christoforidis

First World Problems: The Solar System’s Smallest Planet Is Shrinking

Images captured by NASA’s MESSENGER spacecraft have provided an illustration of Mercury’s shrinking and wrinkling surface over the past 4 billion years. While the behavior of Earth’s outermost shell can best be explained through plate tectonics and the shifting of our lithosphere, Mercury has but one solid shell for a crust. As the planet’s molten core has cooled since its formation billions of years ago, the planet itself has contracted causing Mercury’s rocky exterior to crack and shift to accommodate the smaller size, much like the wrinkles that form on the skin of an apple skin as it dries out and shrinks.

“We see the landscape literally crumpling up,” said William McKinnon, a professor in the Department of Earth and Planetary Sciences at Washington University in St. Louis. “Massive slabs of rock are sliding over one another.”

As for the change in size, the study found in the journal Nature Geoscience notes that Mercury has seemingly contracted in radius in some locations as far as 7 kilometers, making the modern-day radial measurement of the planet 2,440 kilometers.

NASA’s MESSENGER spacecraft ended its mission today, as planned, by colliding with Mercury. Read more: http://www.penny4nasa.org/2015/04/30/watch-messenger-spacecraft-end-of-mission/

Celebrate NASA’s MESSENGER spacecraft by writing to Congress to let them know you support doubling funding for NASA: http://www.penny4nasa.org/take-action/

Read more:
http://goo.gl/4Kw7DM
http://goo.gl/ZCXTNh
http://goo.gl/XcuXKL

youtube

The lithosphere as literature, the aesthetics of the asthenosphere, and Pangaea as a pop-up book. It’s a tactile tectonics lesson!

It’s hard to believe, but the now-common idea that the Earth’s crust (and the continents upon it) are surfing along waves of hot mantle was only put forth by Alfred Wegener about 100 years ago, and not widely accepted by scientists until the 1950’s!

(Educators: Check out the full lesson at TED-Ed)

The Dinaric Alps

The Dinaric Alps are a not so widely known mountain chain that spans the Balkan countries of Albania, Kosovo, Serbia, Montenegro, Croatia, and Bosnia and Herzegovina. The highest summit of the Dinaric Alps is Maja Jezece in Albania, whose peak reaches 2,694 meters.

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A new map of Mars’ gravity made with three NASA spacecraft showing the Tharsis volcanoes and surrounding flexure. The white areas in the center are higher-gravity regions produced by the massive Tharsis volcanoes, and the surrounding blue areas are lower-gravity regions that may be cracks in the crust (lithosphere).

Map of Mars Gravity

A new map of Mars’ gravity made with three NASA spacecraft is the most detailed to date, providing a revealing glimpse into the hidden interior of the Red Planet. The map was derived using Doppler and range tracking data collected by NASA’s Deep Space Network from three NASA spacecraft in orbit around Mars: Mars Global Surveyor, Mars Odyssey, and the Mars Reconnaissance Orbiter.

This view of the Martian gravity map shows the Tharsis volcanoes and surrounding flexure. Tharsis is a volcanic plateau on Mars thousands of miles across with the largest volcanoes in the solar system. The white areas in the center are higher-gravity regions produced by the massive Tharsis volcanoes, and the surrounding blue areas are lower-gravity regions that may be cracks in the crust (lithosphere).

Image Credit: MIT/UMBC-CRESST/GSFC

Folded flysch

When continents start their slow grinding collisions a typical sequence of rocks results, named after the German word for ‘to flow’ by a Swiss geologist in 1827. The original sequence came from the forelands of the Alps, where interbedded limestones, sandstones and shales marked the remnants of the earliest days of the mountain chain. As the continents approach each other and the crust begins to thicken, the increased weight causes the crust to bend in a process called lithospheric flexure into a deep ocean basin. The downwarp creates a perfect trap for the new sediment being eroded from the growing topography of the developing mountain front as the orogenic event builds. Flysh forms in deep marine environments, in low energy sedimentological surroundings (as opposed to the high energy one of the seashore)

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the story goes like this:

he spent the day with his friends so she had to wait for him to come back. had to take her mind off of him. so she took care of her niece for ten hours straight, she was never fond of selfies but she tried every snapchat filter that day. because she had to not think about him. she had to forget for a while, that he was not there. she assumed that vodka would be too strong and that she might forget everything. brown eyed girl just wanted to do something else because waiting would mean she misses him, and she was tired of missing him. to be honest it’s been a week. she felt the distance. like fault lines across the lithosphere, unfinished bridges or the ones waiting to be burned down.

brown eyed girl said hi over messenger. “hi?? are you ignoring me???” brown eyed girl needed to vent. brown eyed girl was fed up. brown eyed girl was tired or waiting. but she wouldn’t let him know that. because if he knew she was upset because of him, they would argue. and that was the last thing that they needed.

still, they fought over messenger. something about her apologizing for being a bitch and him trying to help. she said he didn’t know how to listen, he told her she didn’t do anything wrong. she apologized but he wouldn’t accept. because for him, she was not in the wrong. she had to beg him to accept her apology, he did, eventually.


the story goes like this:

brown eyed girl says hi over messenger and they forget about what happened moments before because they know that having each other is more important that their petty fights. brown eyed girl cracks jokes over messenger and he laughs. she hears it through the songs blasting on her earphones. she smiles. brown eyed girl is happy again.


the story goes like this:

brown eyed girl will apologize even if she knows she’s not in the wrong. brown eyed girl will forgive him for this, will forgive him in the future, will forgive him either way because she loves him. brown eyed girl loves him and tonight he will sleep alright.

—  dad told me to forgive, mom taught me how to love
We

We are two unstable
tectonic plates
Uncontrollable

Moving under the lithosphere
Endlessly
Tumultuously

We follow the rules of disorder
Each words we said to each other
Are earthquakes beyond the scale of Richter

The Continental Drift theory said
In 65.000 years we wouldn’t even know each other

I would’ve subducted
And you’d be a new landmass

Maybe a tundra
or a super continent
home to a vast range of biodiversity

Maybe you’ll forget me

But it doesn’t matter
Any expert can see
the evidence

of a tectonic collision
involving you and me

The unique geology of Macquarie Island. 

Macquarie Island is located in the south-west Pacific Ocean, between Australia and New Zealand, and officially belongs to the Australian state of Tasmania. The island is tiny, only 5 km (3.1 mi) wide and 35 km (21.7 mi) long, covering a total area of 128 km2 (49 sq mi). It is a unique place: it is the only sub-Antarctic island to be fully oceanic in origin, and it is the only known site on Earth where an ophiolite complex is presently undergoing formation in it’s original geological setting, actively exposing mantle rocks on the Earth’s surface. 

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Magnetically Attracted to the Lithosphere?

We’ve covered issues concerning the magnetic field of the Earth before (http://tinyurl.com/o7rpp44 ), but these concentrated on the immense magnetic field created by the rotation of the liquid core within the Earth, resulting in such phenomena as the Northern Lights and, oh, Life on Earth as we Know It.

This study, reported by Stefan Maus, documents the magnetism of the rocks of the Earth itself.

The greater magnetic field of the Earth apparently is screened from the database as long wavelength phenomena: shorter wavelength magnetic data is interpreted as having its source in the Earth’s Lithosphere. This, applied to the spherical representation of our planet, produces this bumpy – lumpy picture. Each positive “bump” corresponds to areas in which magnetic minerals are present in higher than average amounts, chiefly magnetite itself. At temperatures over 400C – 500C, these minerals lose their magnetism. Note: these are temperatures restricted to the lithosphere, thus the local magnetism isn’t apparently from deeper, hotter sources.

It certainly does seem that the continental plates are lumpier and bumpier than the oceanic tectonic plates: the former vary in source rock, some being notably lacking in magnetites like in thick sedimentary units (notice US Eastern Coast and even Gulf of Mexico), and some extremely rich in these minerals such as metamorphic terranes and very old parts of the crust (I wonder if that great bump in the Eastern US has anything to do with the Magnet Cove locality of Arkansas?) The oceanic areas are far more homogeneous, as are the relatively young lithospheric sections produced in their spreading centers: yes, there’s a fair amount of magnetite in these oceanic rocks (if you write that any basalt has 1%modal magnetite, no one will ever question this), but it’s uniform in its distribution.

So, what does this leave us with? Something of a tool for comparing our relatively well understood lithosphere with that of other planets and moons that lack strong magnetic fields and do have cool enough surfaces to retain magnetic minerals. Indeed, it is by comparisons such as this that the origin of much of the lunar surface (including whether there was once a lunar magnetic field) could be puzzled out.

I find this magnetically attractive!

Annie R

This image and video clip was created from satellite studies, at present the CHAMP satellite, and is posted at the CIRES (Cooperative Institute for Research in Environmental Sciences):
http://geomag.org/info/lithosphere.html

For further interest, try:
http://www.liv.ac.uk/~holme/lith.html
http://www.gfz-potsdam.de/en/research/organizational-units/departments-of-the-gfz/department-2/earths-magnetic-field/topics/background/lithospheric-field/
http://blogs.airspacemag.com/moon/2009/02/the-strange-story-of-lunar-magnetism/

Earth’s deepest earthquakes

Normally, Earthquakes are a shallow phenomenon, confined to Earth’s upper ~20 kilometers. There are only a couple places where earthquakes take place any deeper than that; subduction zones.

Based on its physical properties, the outer portion of the Earth can be divided into two layers, the lithosphere and the asthenosphere. The lithosphere is the outermost layer of the planet, including the crust, and it is cold. So cold, in fact, that it is able to break and fracture.

The asthenosphere, deeper in the planet, is warm. Warm enough, in fact, that the rocks are able to move and flow without breaking. Apply a force to a rock this hot and, over geologic time, it will flow like a glacier or like silly putty. 

For an earthquake to happen, the rocks have to be cold enough to break. If they can flow, they won’t fracture and there won’t be any earthquakes. The boundary between the lithosphere and the asthenosphere is the deepest depth that an earthquake can happen at, unless cold material is taken down deeper into the mantle.

That’s exactly what happens at subduction zones, where old, cold, oceanic plates are taken down into the mantle. Those rocks have been at the surface for hundreds of millions of years and they take time to warm up. They stay cold up to hundreds of kilometers deep into the Earth, and during this portion of their voyage they continue producing earthquakes. Scientists using seismometers can locate these earthquakes and actually track that they get deeper farther from the subduction zone. This layer of deep earthquakes within sinking plates is known as the Wadati-Benioff zone, after two geophysicists, and is a solid demonstration of how subduction zones work. These earthquakes let us see where the plates are as they sink.

-JBB

Image credit: Marshak, Essentials of Geology, licensed to me for teaching purposes

Orogeny

We often talk about orogenies and orogenic events here at The Earth Story, but what is an orogeny?

An orogeny describes a series of forces and events leading to the severe structural deformation of the Earth’s crust and uppermost mantle (also known as the lithosphere). So in simple terms, an orogeny is a mountain building event. Occurring at the boundary where continental plates meet (though they can occur where a continental plate overrides an oceanic plate), the response to orogenic forces is basically a “crumpling” of the rock, leading to highly deformed and metamorphosed areas of rock, which extend far underneath the resulting mountain belt, and far beyond the front.

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