Magnetic anomaly deep within Earth’s crust reveals Africa in North America

Date:

Share post:

The repeated cycles of plate tectonics that have led to collision and assembly of large supercontinents and their breakup and formation of new ocean basins have produced continents that are collages of bits and pieces of other continents.

Magnetic anomaly deep within Earth's crust reveals Africa in North America
Antonio Snider-Pellegrini’s Illustration of the closed and opened 
Atlantic Ocean (1858) [Credit: eurasiareview]

Figuring out the origin and make-up of continental crust formed and modified by these tectonic events is a vital to understanding Earth’s geology and is important for many applied fields, such as oil, gas, and gold exploration.

In many cases, the rocks involved in these collision and pull-apart episodes are still buried deep beneath Earth’s surface, so geologists must use geophysical measurements to study these features.

This new study by Elias Parker Jr. of the University of Georgia examines a prominent swath of lower-than-normal magnetism — known as the Brunswick Magnetic Anomaly — that stretches from Alabama through Georgia and off shore to the North Carolina coast.

The cause of this magnetic anomaly has been under some debate. Many geologists attribute the Brunswick Magnetic Anomaly to a belt of 200 million year old volcanic rocks that intruded around the time the Atlantic Ocean.

In this case, the location of this magnetic anomaly would then mark the initial location where North America split from the rest of Pangea as that ancient supercontinent broke apart. Parker proposes a different source for this anomalous magnetic zone.

Drawing upon other studies that have demonstrated deeply buried metamorphic rocks can also have a coherent magnetic signal, Parker has analyzed the detailed characteristics of the magnetic anomalies from data collected across zones in Georgia and concludes that the Brunswick Magnetic Anomaly has a similar, deeply buried source.

The anomalous magnetic signal is consistent with an older tectonic event — the Alleghanian orogeny that formed the Alleghany-Appalachian Mountains when the supercontinent of Pangea was assembled.

Parker’s main conclusion is that the rocks responsible for the Brunswick Magnetic Anomaly mark a major fault-zone that formed as portions of Africa and North America were sheared together roughly 300 million years ago — and that more extensive evidence for this collision are preserved along this zone.

One interesting implication is that perhaps a larger portion of what is now Africa was left behind in the American southeast when Pangea later broke up.

Source: Geological Society of America  [April 02, 2014]

ADVERTISEMENT

spot_img

Related articles

Archaeologists ready for Bronze Age boat build

The processes behind building the oldest boat ever found in Western Europe will be investigated by a team...

Two possible excavation spots revealed at Old Vero Man site

Results from a ground penetrating radar survey conducted in March at the Old Vero Man site in Vero...

Solving the Midwest’s biggest geologic mystery

Geologists from Northwestern University, the University of Illinois at Chicago, the University of Oklahoma and Purdue University have...

New whale species unearthed in California highway dig

Chalk yet another fossil find up to roadcut science. Thanks to a highway-widening project in California’s Laguna Canyon,...

Revolutionary theory of dark matter

The universe abounds with dark matter. Nobody knows what it consists of. University of Oslo physicists have now...

Istanbul metro dig reveals Byzantine shipwreck

Archaeological digs at Yenikapı, the site of excavations for an important transfer hub in İstanbul's metro system, the...

Mexico finds 50 skulls in sacred Aztec temple

Mexican archaeologists said Friday they uncovered the largest number of skulls ever found in one offering at the...

Uncovering Africa’s oldest known penguins

Africa isn't the kind of place you might expect to find penguins. But one species lives along Africa's...