Massive 'Lava Lamp' Blobs Deep Inside Earth Have Scientists Puzzled

Two continent-size blobs of hot — and possibly molten — rock can be found deep underground, about halfway to the center of the Earth, according to a new study. These curious structures — each of which is so large that it would be 100 times taller than Mount Everest...

One of the blobs is located beneath the Pacific Ocean, and the other can be found beneath the Atlantic. These underground structures start where the Earth's mantle meets the core, but they send "plumes" up through the rock like a Lava Lamp, the researchers said.

Different types of seismic waves travel at different speeds, depending on the type of rock the blobs are moving through. And by comparing the timing and delay of signals from multiple locations, seismologists can build models of what's going on in the Earth's interior.

The blobs are characterized by slower wave speeds, which suggests they are a different temperature from the rest of the Earth's mantle...But at some of the edges, normal wave speeds transition abruptly to low wave speeds. A pure temperature difference would result in a more gradual change... which suggests the blobs are likely made up of something different from what makes up their surroundings.

Because they're big and characterized by the slower wave speeds, the blobs have been called large low velocity provinces (LLVPs). And ... scientists call the areas large low shear velocity provinces (LLSVPs).

If an especially large "superplume" of magma from one of these blobs were to make it to the surface, it would result in "massive eruptions where the lava will come out for millions of years at a time," ...There isn't much cause for alarm, though. "The next one could be on its way," he said, "but it could be a million years away."

Thanks BenLurkin.

Fossil Mantle Plume Under South America
by William Corliss
"The conduit appears to have remained geographically fixed with respect to the overlying continent despite thousands of kilometers of South American plate motion. This observation runs contrary to a major tenet of plate tectonic theory -- that the motion of lithospheric plates is essentially independent of flow in the upper mantle beneath the plates -- and implies that the upper mantle and the overlying South American continent have remained coupled since the breakup of the Gondwanaland super-continent and opening of the South Atlantic Ocean some 120 million years ago.

Actually, that conclusion presupposes that there was a Gondwanaland in the first place.

But What About The Hawaiian Volcanic Chain?
by William Corliss
P.D. Ihinger is challenging the well-entrenched "Hawaiian-volcanic-chain" theory. For example, the Hawaiian volcanoes do not line up exactly. There are dozens of short, overlapping segments rather than a continuous trace across the Pacific basin. On the map, you will also see a sharp dog-leg in the trace. Further, the volcanoes Mauna Loa and Mauna Kea, only 40 kilometers apart, disgorge lavas that are distinctly different.
Researchers Suggest Answer to Geological Puzzle
National Science Foundation
SMU geologists Rebecca Ghent and Douglas Oliver studied the location of the major hot spots and determined that a disproportionate number occur at latitudes between 20 and 30 degrees north and south of the equator. Their observation became much more significant when the hot spots were weighted according to the amount of volcanic material that they produced. Statistical analysis shows that the likelihood of this distribution arising by chance is less than one percent... Oliver and Ghent said their observation may shed light on other geological phenomena, such as the development of superplumes, which are clusters of mantle plumes arriving together at the Earth's surface. Scientists believe that massive superplume events are responsible for some of the major changes that have occurred on the Earth, such as the breakup of the supercontinent known as Pangea into the present continents.
The Earth Is Expanding And We Don't Know Why
by William R. Corliss
Science Frontiers #37
Jan-Feb 1985
"The geological and geophysical implications of such Earth expansion are so profound that most geologists and geophysicists shy away from them. In order to fit with the reconstruction that seems to be required, the volume of the Earth was only 51 per cent of its present value, and the surface area 64 per cent of that of the present day, 200 million years ago. Established theory says that the Earth's interior is stable, an inner core of nickel iron surrounded by an outer layer that behaves like a fluid. Perhaps we are completely wrong and the inner core is in some state nobody has yet imagined, a state that is undergoing a transition from a high-density state to a lower density state, and pushing out the crust, the skin of the Earth, as it expands."

(Owen, Hugh; "The Earth Is Expanding and We Don't Know Why, "New Scientist, p. 27, November 22, 1984.)
The Tarim APWP Paradox
Gilder, S; Cogne, J; Courtillot, V; Chen, Y; Gomez, J
Central Asia boasts one of the world's densest regions sampled for paleomagnetic data thanks to numerous sections of well-exposed rocks possessing stable remanent magnetizations. Such is the case for the Tarim craton, which is represented by a quasi-continuous time sequence of paleomagnetic poles since the Permo-Carboniferous. Most of these poles are derived from studies demonstrating positive fold and-or reversal tests, with N equal to or greater than 6 sites or 50 samples. Samples collected from Permo-Carboniferous rocks usually have reverse polarities, and samples collected from Cretaceous rocks usually have normal polarities, consistent with the geomagnetic polarity time scale. Despite the apparent excellent quality of the paleomagnetic data from Tarim, they impose geologically unrealistic tectonic displacements when compared to the Eurasian and-or Indian APWPs. This leads to the Tarim APWP paradox: is there a problem (inclination shallowing, overprinting, etc.) with the plentiful Tarim data, or is the Eurasian APWP not representative of the land east of the Ural Mountains? If the latter is true, then previous tectonic reconstructions must be reconsidered. If the former is true, then when/how can we rely on the paleomagnetic data? We present arguments showing that both scenarios have their pros and cons.
How Did Glacial Deposits Form 600 Million Years Ago?
Dr. David Pollard, research associate, Penn State College of Earth and Mineral Sciences' Environmental Institute, and James K. Kasting, professor of geosciences at Penn State, believe that glacial deposits that formed on tropical land areas around 600 million years ago could only have formed after the Earth's oceans were entirely covered by thick sea ice. Ice can accumulate in the tropics only if temperatures are below freezing or around freezing with large amounts of snowfall. Tropical glaciers exist today only on high mountain peaks such as the Andes and Mt. Kilimanjaro, and do not reach anywhere near sea level. As the earth cools, the oceans begin freezing. The high reflectivity of the snow and ice that covers the northern and southern oceans reflects, rather than absorbs, the sun's heat and further cools the planet. The researchers conclude that it is unlikely that tropical sea level glacial deposits formed before the collapse into snowball Earth. However, having them form after the oceans freeze also seemed problematic because once the oceans are frozen, the rates of precipitation decrease drastically, to only a few millimeters per year.
Freeze-fry from the snowball Earth
by Christina Reed
On Dec. 14, Daniel Schrag of Harvard University] presented recent observations in favor of the snowball Earth at the American Geophysical Union’s meeting in San Francisco, which lasted from Dec. 12–17...

But some scientists still remain skeptical. During a presentation at the AGU meeting, Gregory Jenkins of Pennsylvania State University supported what is called the high obliquity hypothesis over the snowball Earth hypothesis. Jenkins argued that climatic conditions during the Neoproterozoic resulted from a severe tilt of Earth on its axis, possibly caused by the impact of the planetoid that formed the moon. Although a tilted Earth may have cooled the equator and warmed the poles, the theory is still hotly debated as an explanation because it seems to require low-latitude cooling prior to Neoproterozoic glacial events.

Schrag and others defend the snowball Earth theory, saying it brings context to mysteries that have plagued the geological community for decades. It explains how glaciers survived in the tropics, how iron-rich rock emerged in an oxygen-enriched world and how warm-water carbonate rocks found themselves perched atop glacial deposits. It may even explain the explosion of life in the Cambrian.

[P]aleomagnetism specialist Joe Kirschvink of Caltech linked the effect a frozen Earth would have on the hydrological cycle to a buildup of volcanic carbon dioxide. If ice covered the oceans to the equator, it would block off evaporation, dry up the clouds and deny water the chance to erode the land. Carbon dioxide would build up in the atmosphere instead of being washed out by rain and carried back to the oceans as carbonates from land. With enough carbon dioxide, the "snowball Earth" would then become a hothouse, Kirschvink said in a 1992 paper published in the bookThe Proterozoic Biosphere.

In 1992, Kenneth Caldeira of Lawrence Livermore National Laboratory and James F. Kasting of Pennsylvania State University calculated that the amount of carbon dioxide needed to reverse the snowball effect would be 350 times present-day levels. With a global average of 50°C below zero, Earth would bake under extreme global warming to 40–50°C in only a few thousand years.
Scientists Poke Holes in 'Snowball Earth' Hypothesis
National Science Foundation
Press Release 05-173
September 29, 2005
Frank Corsetti of USC, a co-author on the study, said "this is the first real evidence that substantial photosynthesis occurred in the Earth's oceans during the extreme ice age 700 million years ago, which is a challenge for the snowball theory."

The evidence does not prove large parts of the ocean remained free of sheet ice during the pre-Cambrian glaciation. Although unlikely, Olcott said it is possible one of the tiny "refugia" under the "Snowball Earth" hypothesis allowed such marine life to exist.

But, she said, "finding the one anomalous spot would be quite unlikely," adding that the samples she studied came from an extensive formation of rocks with similar characteristics.

"At what point does an enormous refugium become open ocean?" she asked.

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