(Press-News.org) New research shows that three sites spread along an approximately 620-mile portion of today’s Denali Fault were once a smaller united geologic feature indicative of the final joining of two land masses. That feature was then torn apart by millions of years of tectonic activity.
The work, led by associate professor Sean Regan at the University of Alaska Fairbanks Geophysical Institute and UAF College of Natural Science and Mathematics, is featured on the cover of the December edition of Geology, the journal of The Geological Society of America.
Regan is the research paper’s lead author. UAF co-authors include doctoral student McKenzie Miller, recent master’s graduate Sean Marble and research assistant professor Florian Hofmann. Other co-authors are from St. Lawrence University, South Dakota School of Mines and Technology and the University of California, Santa Barbara.
“Our understanding of lithospheric growth, or plate growth, along the western margin in North America is becoming clearer, and a big part of that is related to reconstruction of strike-slip faults such as the Denali Fault,” Regan said. “We’re starting to recognize those primary features involved in the stitching, or the suturing, of once-distant land masses to the North American plate.”
The research focused on formations at three locations: the Clearwater Mountains of Southcentral Alaska, the Kluane Lake region of Canada’s southwestern Yukon, and the Coast Mountains near Juneau. Previous thinking among geologists is mixed, with some suggesting the three locations formed individually.
Regan’s historical reconstruction of 300 miles of horizontal movement on the Denali Fault over millions of years found that the three locations at one time formed a terminal suture zone. A terminal suture zone represents the final integration of tectonic plates or crustal fragments into a larger mass.
Regan’s work defines one of several places where the Wrangellia Composite Terrane, an oceanic plate that originated far from its current position, accreted to the western edge of North America between 72 million and 56 million years ago.
“When you think about geologists crawling around Earth’s surface trying to understand what the heck happened, it makes some sense that they might not link things that are so far apart,” Regan said of the three sites he studied. “With different geologists working in different areas, the dots don’t really get connected until you can reconstruct deformation on the Denali Fault.”
Regan’s reconstruction focused on the three sites’ inverted metamorphism, a geological phenomenon where rocks formed under higher temperatures and pressures are found overlying rocks formed under lower temperatures and pressures. This is the reverse of the typical sequence observed in regional metamorphism, where temperature and pressure generally increase with depth.
Inverted metamorphism is a key indicator of tectonic complexity and helps geologists reconstruct the processes of crustal deformation and mountain building.
“We showed that each of these three independent inverted metamorphic belts all formed at the same time under similar conditions,” Regan said. “And all occupy a very similar structural setting. Not only are they the same age, they all behaved in a similar fashion. They decrease in age, structurally, downward.”
Regan connected the three locations by analyzing their monazite, which consists of the rare earth elements lanthanum, cerium, neodymium and sometimes yttrium. He collected monazite from the two Alaska locations and used Kluane data published earlier in the year by another scientist.
“It is just the most special little mineral,” Regan said. “It can participate in a lot of reactions, so we can use it as a way to track the mineralogical evolution of a rock.”
Regan began his quest after reading a 1993 paper by researchers at the University of Alberta and University British Columbia and published in Geology. That paper asserted similarities in the Denali Fault region later studied by Regan, but only went as far as labeling them as a single metamorphic-plutonic belt.
A metamorphic-plutonic belt is a region characterized by the close association of metamorphic rocks and plutonic rocks that form as a result of intense tectonic activity, typically during mountain-building processes. These belts are commonly found in areas where tectonic plates converge.
“It was amazing to me that the 1993 paper hadn’t caught more attention back in the day,” Regan said. “I had this paper hung up on my wall for the last four years, because I thought it was really ahead of its time.”
CONTACTS:
• Sean Regan, University of Alaska Fairbanks Geophysical Institute, sregan5@alaska.edu
• Rod Boyce, University of Alaska Fairbanks Geophysical Institute, 907-474-7185, rcboyce@alaska.edu
END
Denali Fault tore apart ancient joining of two landmasses
2024-12-19
ELSE PRESS RELEASES FROM THIS DATE:
National Institute awards $2.18 million to Lebeche, Ishrat for innovative stroke research
2024-12-19
The National Institute of Neurological Disorders and Stroke has awarded $2.18 million to two researchers at the University of Tennessee Health Science Center for a project focused on a new drug treatment to protect the brain after a stroke. The principal investigators are Djamel Lebeche, PhD, professor in the Department of Physiology, and Tauheed Ishrat, PhD, associate professor in the Department of Anatomy and Neurobiology.
Type 2 diabetic patients are two to six times more likely to suffer from an acute ischemic stroke. These patients also face additional complications such as blood-brain barrier leakage, swelling, bleeding, and poor recovery after a stroke. ...
American Society for Nutrition Foundation and Novo Nordisk Foundation launch two prestigious awards to inspire next-generation innovation in nutrition science
2024-12-19
The American Society for Nutrition Foundation (ASNF) and the Novo Nordisk Foundation (NNF), two philanthropic 501(c)(3) organizations, have joined forces to launch new awards to celebrate excellence in nutrition science and provide critical support to researchers at pivotal stages of their careers.
Scientific awards do more than honor achievements—they propel careers, fuel discovery, and underscore the vital contributions of scientists addressing global public health challenges. These new awards, named in honor of trailblazing Danish scientists Henrik Dam and Flemming Quaade, aim to inspire innovative research in nutrition and foster ...
Research shows how music can reduce distress
2024-12-19
A new study has demonstrated for the first time how and why music can reduce distress and agitation for people with advanced dementia.
There are an estimated one million people living with dementia in the UK and over half are diagnosed with advanced dementia, which can require specialist care and is often accompanied by behaviour such as agitation, aggression, wandering, and resistance to care.
Published in the journal Nature Mental Health, the research reveals the different benefits of music therapy, identifies mechanisms to explain why music can have these effects, and provides a blueprint for implementing effective music therapy for people with advanced dementia.
Music ...
Growth mindset might help protect mental health during challenging times
2024-12-19
Growth mindset might help protect mental health during challenging times, being associated with lower levels of depression and higher well-being in COVID-19 pandemic study of Californian adults aged 19-89.
++++
Article URL: https://journals.plos.org/mentalhealth/article?id=10.1371/journal.pmen.0000182
Article Title: The implications of growth mindset for depression, well-being, and adjustment over 2 years during the COVID-19 pandemic
Author Countries: United States
Funding: This research was supported by an NSF RAPID grant (grant number BCS-2029575) and was also partially supported by an American Psychological Foundation Visionary Grant and an NSF CAREER Award ...
Stanford Medicine scientists design workaround that improves response to flu vaccine
2024-12-19
Stanford Medicine scientists have designed a way to make our seasonal influenza vaccinations more broadly effective and possibly to protect us from new flu variants with pandemic potential. In a study set to publish Dec. 20 in Science, they’ve shown in cultured human tonsil tissue that the method works.
Flu season is upon us, and flu is no joke. Every year, the influenza virus kills hundreds of thousands of people and sends millions to the hospital. The seasonal flu vaccine many of us get is intended to keep that from happening, by giving our immune system a heads-up that speeds its ...
Virginia Tech study extends chart of life by nearly 1.5 billion years
2024-12-19
If all the world's a stage and all the species merely players, then their exits and entrances can be found in the rock record.
Fossilized skeletons and shells clearly show how evolution and extinction unfolded over the past half a billion years, but a new Virginia Tech analysis extends the chart of life to nearly 2 billion years ago.
The chart shows the relative ups and downs in species counts, telling scientists about the origin, diversification, and extinction of ancient life.
With this new study, the chart of life now includes life forms from the Proterozoic Eon, 2,500 million to 539 million years ago. Proterozoic life was generally smaller and squishier — like sea ...
Seasonal flu vaccine study reveals host genetics’ role in vaccine response and informs way to improve vaccine
2024-12-19
Most people who get the seasonal influenza vaccine – which contains strains of viruses from distinct virus subtypes – mount a strong immune response to one strain, leaving them vulnerable to infection by the others, and researchers have long wondered what impacts such variable responses more – host genetics or prior exposure to virus strains. Now, researchers report that host genetics is a stronger driver of these individual differences in influenza vaccine response. Their study also presents a novel vaccine platform that improved protection against diverse influenza subtypes when tested in animal models and human organoids. ...
Filling a gap: New study uncovers Proterozoic eukaryote diversity, and how environment was a driver
2024-12-19
Advanced tools and expanded fossil datasets have painted a clearer picture of the eukaryotic diversity of the Proterozoic eon, which has been hard to quantify. The findings show that Earth's severe Cryogenian glaciations catalyzed a pivotal shift in the evolution and diversity of early eukaryotes during this eon, 2500 to 538 million years ago. This work underscores the interplay between Earth’s environmental perturbations and the evolutionary trajectories of early life. Quantifying global fossil diversity provides valuable insights into the evolutionary history of life on Earth and its relationship with environmental changes. This is exemplified by the well-known mass extinction ...
In aged mice with cognitive deficits, neuronal activity and mitochondrial function are decoupled
2024-12-19
New findings in mice have uncovered a crucial mechanism linking neuronal activity to mitochondrial function, researchers report, revealing a potential pathway to combat age-related cognitive decline. Mitochondria play a pivotal role in meeting the dynamic energy demands of neuronal activity, producing adenosine triphosphate (ATP) primarily via oxidative phosphorylation (OXPHOS). However, in the aging mammalian brain, mitochondrial metabolism deteriorates, leading to profound effects on neuronal and circuit functionality. The breakdown of the OXPHOS pathway contributes to oxidative stress and ...
Discovered: A protein that helps make molecules for pest defense in Solanum species
2024-12-19
A protein – dubbed GAME15 – is the missing link in the pathway that Solanum plants like potatoes use to make molecules for chemical defense: steroidal glycoalkaloids (SGAs). The findings pave the way for engineering this biosynthetic pathway into other plants, enabling innovative applications in agriculture and biotechnology. “The discovery … provides a key to engineering SGAs for food, cosmetics, and pharmaceuticals,” write the authors. Plants produce a wide variety of secondary metabolites that are crucial for their growth ...