"I can go to the Franklin Mountains in West Texas and stand next to what was once part of Coats Land in Antarctica," said Staci Loewy, a geochemist at California State University, Bakersfield, who led the study. "That's so amazing."
Loewy and her colleagues discovered that rocks collected from both locations have the exact same composition of lead isotopes. Earlier analyses showed the rocks to be the exact same age and have the same chemical and geologic properties. The work, published online (ahead of print) in the September issue of the journal Geology, strengthens support for the so-called SWEAT hypothesis, which posits that ancestral North America and East Antarctica were joined in an earlier supercontinent called Rodinia.
The approximately 1.1 billion year old North American Mid-continent Rift System extends across the continent from the Great Lakes to Texas. Volcanic rocks associated with the rift, which appears to represent an aborted tectonic attempt to split the ancestral North American continent of Laurentia, are well exposed in the Keweenaw Peninsula of the Upper Peninsula of Michigan from which they take their name, the Keweenawan large igneous province. The rift extends in the subsurface beneath Minnesota, Iowa, Nebraska, Kansas and Oklahoma to the Franklin Mountains near El Paso, Texas where related rocks are exposed. In this latest report, Loewy, Ian Dalziel, research professor at The University of Texas at Austin, Richard Hanson of Texas Christian University and colleagues from several overseas institutions, find that rocks barely peeking through the ice in Coats Land, a remote part of the Antarctic continent south of the Atlantic Ocean basin, reflect a former continuation of the North American rift system. Loewy began her collaboration with Dalziel several years ago as a graduate student at the University of Texas at Austin.
Loewy et al. use new lead (Pb) isotopic data from the 1.1-billion-year-old rocks from Coats Land, to constrain the positions of Laurentia (ancestral North America) and Kalahari (ancestral southern Africa) in the 1-billion-year-old supercontinent, Rodinia. The Coats Land rocks are identical in age to both the Keweenawan large igneous province of the North American mid-continent rift and the contemporaneous Umkondo large igneous province of southern Africa. Comparison of the isotopic compositions, however, unequivocally links the Coats Land rocks with the Keweenawan province. Together with paleomagnetic data this suggests that the Coats Land block was a piece of Laurentia near west Texas 1.1 billion years ago. Furthermore, the Coats Land block collided with the Kalahari Precambrian craton of Africa during a 1-billion-year-old collision. Based on this reconstruction, Laurentia collided with Kalahari along Antarctica’s Maud mountain belt, which would represent a continuation of the 1-billion-year-old Grenville mountain belt of eastern and southern North America.
Thus the tiny Coats Land block of Antarctica is a ‘tectonic tracer’ providing critical clues to the geographic relationships between three of the major continents of the planet in the time interval 1.1 – 1.0 billion years ago, just prior to the opening of the Pacific Ocean basin, the hypothesized ‘Snowball Earth’ glaciations, and the rise of multi-cellular life.Coats Land crustal block, East Antarctica: A tectonic tracer for Laurentia?
Abstract is available at http://geology.gsapubs.org/.Additional contact: co-author Ian W. D. Dalziel, Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin.
Representatives of the media may obtain complementary copies of Geology articles by contacting Christa Stratton at the address above. Please discuss articles of interest with the authors before publishing stories on their work, and please make reference to Geology in articles published.
Non-media requests for articles may be directed to GSA Sales and Service, firstname.lastname@example.org.
*S.L. Loewy1, I.W.D.Dalziel2, S. Pisarevsky3,7, J.N. Connelly4, J. Tait3, R.E. Hanson5, D. Bullen6
1. Department of Geology, California State University, Bakersfield, Bakersfield, CA 93311
2. Institute for Geophysics, The University of Texas at Austin, Austin, Texas 78758-4445
3. School of GeoScience, University of Edinburgh, King’s Buildings, Edinburgh, EH9 3JW, UK
4. Centre for Star and Planet Formation, Copenhagen University, Copenhagen 1350, Denmark
5. School of Geology, Energy and the Environment, Texas Christian University, Fort Worth, TX 76129
6. School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth PO1 3QL, UK
7. School of Earth and Environment, University of Western Australia, Crawley, WA 6009, Australia
Christa Stratton | EurekAlert!
Monitoring lava lake levels in Congo volcano
16.05.2018 | Seismological Society of America
Ice stream draining Greenland Ice Sheet sensitive to changes over past 45,000 years
14.05.2018 | Oregon State University
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology