Oldest-ever igneous meteorite contains clues to planet building blocks


August 2, 2018

Scientists believe the solar system was formed some 4.6 billion years ago when a cloud of gas and dust collapsed under gravity, possibly triggered by a cataclysmic explosion from a nearby massive star or supernova. As this cloud collapsed, it formed a spinning disk with the sun in the center.

Piece by piece, scientists have been working on establishing the formation of the solar system with clues from space. Now, new research has enabled scientists Meenakshi Wadhwa and Daniel Dunlap at Arizona State University’s Center for Meteorite Studies in the School of Earth and Space Exploration, as well as researchers from the University of New Mexico and NASA’s Johnson Space Center to add another piece to that puzzle, with the discovery of the oldest-ever dated igneous meteorite. meteorite “Northwest Africa (NWA) 11119 The meteorite “Northwest Africa (NWA) 11119” was found in a sand dune in Mauritania. The rock is lighter in color than most meteorites and is laced with green crystals. Photo courtesy: ASU Center for Meteorite Studies Download Full Image

“The meteorite we studied is unlike any other known meteorite,” co-author Dunlap said. “It has the highest abundance of silica and the most ancient age (4.565 billion years old) of any known igneous meteorite. Meteorites like this were the precursors to planet formation and represent a critical step in the evolution of rocky bodies in our solar system.”

The research on this meteorite, published today in Nature Communications, provides direct evidence that chemically evolved, silica-rich crustal rocks were forming on planetesimals within the first 10 million years prior to the assembly of the terrestrial planets and helps scientists further understand the complexities of planet formation.

A meteorite laced with green crystals

The research began at the University of New Mexico (UNM) with a yet-to-be studied meteorite, called “Northwest Africa (NWA) 11119,” that was found in a sand dune in Mauritania. The rock is lighter in color than most meteorites and is laced with green crystals, cavities and quench melt, a type of rock texture that suggests rapid cooling and is often found in volcanic rocks which cool rapidly or “quench” when brought to the surface quickly.

Using an electron microprobe and a computed tomography (CT) scan at UNM and NASA’s Johnson Space Center facilities, lead author Poorna Srinivasan started to examine the composition and mineralogy of the rock. Srinivasan noted the intricacies of NWA 11119 including its unusual light-green fusion crust.

“The mineralogy of this rock is a very, very different from anything that we've worked on before,” Srinivasan said. “I examined the mineralogy to understand all of the phases that comprise the meteorite. One of the main things we saw first were the large silica crystals of tridymite which is similar to the mineral quartz. When we conducted further image analyses to quantify the tridymite, we found that the amount present was a staggering 30 percent of the total meteorite — this amount is unheard of in meteorites and is only found at these levels in certain volcanic rocks from the Earth.”

Video by University of New Mexico

Determining the age and origin of the meteorite

At ASU’s Center for Meteorite Studies, scientists and co-authors Dunlap and Wadhwa used inductively coupled plasma mass spectrometry in their Isotope Cosmochemistry and Geochronology Laboratory, which helped determine the precise formation age of the meteorite. The research confirmed that NWA 11119 is the oldest-ever igneous meteorite recorded at 4.565 billion years old.

“The purpose of this research was to understand the origin and formation time of an unusually silica-rich igneous meteorite,” said Wadhwa, who is the director of ASU’s Center for Meteorite Studies. “Most other known igneous asteroidal meteorites have ‘basaltic’ compositions that have much lower abundances of silica — so we wanted to understand how and when this unique silica-rich meteorite formed in the crust of an asteroidal body in the early solar system.”

Daniel Dunlap
Daniel Dunlap, a graduate student at the School of Earth and Space Exploration and co-author of this study, performed the isotope analyses for dating NWA 11119 in the Isotope Cosmochemistry and Geochronology Laboratory at ASU. Photo by Laurence Garvie/ASU

In addition, the research involved trying to figure out through chemical and isotopic analyses what body the meteorite could be from. Utilizing oxygen isotopes done in collaboration with co-author Karen Ziegler of UNM’s Center for Stable Isotope lab, the team was able to determine that it was definitely extraterrestrial.

“Based on oxygen isotopes, we know it's from an extraterrestrial source somewhere in the solar system, but we can't actually pinpoint it to a known body that has been viewed with a telescope,” Srinivasan said. “However, through the measured isotopic values, we were able to possibly link it to two other unusual meteorites (Northwest Africa 7235 and Almahata Sitta) suggesting that they all are from the same parent body — perhaps a large, geologically complex body that formed in the early solar system.”

One possibility is that this parent body was disrupted through a collision with another asteroid or planetesimal and some of its ejected fragments eventually reached the Earth’s orbit, falling through the atmosphere and ending up as meteorites on the ground — in the case of NWA 11119, falling in Mauritania at a yet unknown time in the past.

“The oxygen isotopes of NWA11119, NWA 7235, and Almahata Sitta are all identical, but this rock — NWA 11119 — stands out as something completely different from any of the over 40,000 meteorites that have been found on Earth,” Srinivasan said.

asteroid
Asteroids are the remains from the formation of the solar system, some 4.6 billion years ago. Photo: Artist’s rendition — University of New Mexico

Building blocks of planet formation

Most meteorites are formed through the collision of asteroids orbiting the sun in a region called the asteroid belt. Asteroids are the remains from the formation of the solar system, some 4.6 billion years ago. 

The chemical composition ranges of ancient igneous meteorites, or achondrites, are key to understanding the diversity and geochemical evolution of planetary building blocks. Achondrite meteorites record the first episodes of volcanism and crust formation, the majority of which are basaltic in composition.

“This research is key to how the building blocks of planets formed early in the solar system,” said co-author Carl Agee, director of UNM’s Institute of Meteoritics. “When we look out of the solar system today, we see fully formed bodies, planets, asteroids, comets and so forth. Then, our curiosity always pushes us to ask the question, how did they form, how did the Earth form? This is basically a missing part of the puzzle that we've now found that tells us these igneous processes act like little blast furnaces that are melting rock and processing all of the solar system solids. Ultimately, this is how planets are forged.”

The next steps for the ASU team are to detail the chronology of this meteorite (and related meteorites) with new isotopic measurements. These new data will help even more precisely determine the age of this unique meteorite and the implications for the evolution of rocky bodies in the early solar system.

Karin Valentine

Media Relations & Marketing manager, School of Earth and Space Exploration

480-965-9345

Leading in Arizona and worldwide: ASU psychology faculty elected to prominent leadership roles


August 2, 2018

Faculty in the Arizona State University Department of Psychology have recently been elected to leadership positions in several prominent professional associations including three divisions of the American Psychological Association (APA), the Human Behavior and Evolution Society, the Association for Behavior Analysis International and others.

Stephen Goldinger

President-elect of APA Division 3, Society for Experimental Psychology and Cognitive Science ASU Pedestrian Bridge Faculty in the Arizona State University Department of Psychology have recently been elected to leadership positions in several prominent professional associations including three divisions of the American Psychological Association, the Human Behavior and Evolution Society, the Association for Behavior Analysis International and others. Download Full Image

Goldinger, a professor of psychology, will serve a one-year term each as president-elect, president and past-president of APA Division 3. In this leadership role, his job is to ensure that cognitive science is represented in the overall priorities of the APA.

“Because APA overall is strongly focused on clinical psychology, my goal as president is to make Division 3 more relevant to cognitive science academics, especially students and postdocs,” Goldinger said. “Some ideas I have include increasing networking opportunities with a forum to match students with potential postdoctoral mentors and resources to help find nonacademic jobs, and by hosting symposia with topics that are of great impact to cognitive scientists.”

portrait of
Stephen Goldinger

As president, Goldinger will also oversee the newsletter of Division 3, the nomination and selection process for committees, and member recruitment.

Gene Brewer, associate professor of psychology, was elected as a member-at-large to the board of APA Division 3 and will work alongside Goldinger.

David MacKinnon

President-elect of APA Division 5, Quantitative and Qualitative Methods

MacKinnon, Foundation Professor of Psychology, will also serve a year each as president-elect, president and past president of APA Division 5.

MacKinnon has been a member of Division 5 since he earned his doctorate in 1986 and was the Division 5 representative to the APA Council of Representatives for the past four years.

portrait of
David Mackinnon

In his role as president, MacKinnon plans to work on consolidating the three sections of Division 5 — assessment, evaluation measurement and statistics, and qualitative inquiry — into one dynamic division that develops and applies the best methodological tools for psychological research. He also plans to promote and communicate new methods to APA members.

“We will host the Division 5 business meeting at ASU next spring and will have a miniconference the day before that focuses on new statistical methods, service to Division 5, and the teaching of methodology,” MacKinnon said.

The upcoming Division 5 meeting is also in honor of the career of Leona Aiken, President’s Professor of psychology emeritus, who made important contributions to Division 5 and the research and teaching of quantitative psychology methods.

Suniya Luthar

President of APA Division 7, Developmental Psychology

portrait of
Suniya Luthar

Luthar, Foundation Professor of Psychology, is currently serving as president-elect of APA Division 7. Luthar will start her term as president in January.

Before her election as president, Luthar served a three-year term as the Division 7 representative to the APA Council of Representatives.

“As president, my emphasis will be on applications in the real world, or ‘giving science away,’” Luthar said. “We want to bring what we have learned as researchers to benefit the lives of children and families.”

Division 7 has hosted application-focused conferences and prepared statements for policymakers in collaboration with APA Division 37, the Society for Child and Family Policy and Practice, and Division 53, the Society for Clinical Child and Adolescent Psychology.

“APA is intensively involved in policy and advocacy, and I have been called upon to meet with senators to help explain the value of (National Institutes of Health) funding for developmental psychology, among other issues” Luthar said. “I think it is important through my leadership roles that I give back to the organization and profession as best I can.”

Douglas Kenrick

President-elect of the Human Behavior and Evolution Society

portrait of
Douglas Kenrick

Kenrick, professor of psychology, was elected president of the Human Behavior and Evolution Society (HBES). The international society includes researchers from ecology, biology, anthropology, psychology and other disciplines who focus on understanding human behavior in evolutionary terms.

The society hosts an annual conference and publishes the journal Evolution and Human Behavior.

“Across psychology as a whole and especially within the ASU Department of Psychology, there is a growing interest among students to think about human behaviors in terms of evolution,” Kenrick said. “HBES has had an outsized impact on the way people think about human behavior. Thinking in terms of evolution has revolutionized our understanding of how the mind works.”

Kenrick will serve two years each as president-elect, president, and past-president.

More ASU psychology leaders

ASU psychology faculty have leadership roles in addition to the APA and HBES.

• Peter Killeen, professor emeritus of psychology, was elected president of the Association for Behavior Analysis International. The association, which began in 1974, focuses on the philosophy, science, application and teaching of behavioral analysis.

• Federico Sanabria, associate professor of psychology, is president of the International Society for Comparative Psychology.

¨• Danielle McNamara, professor of psychology and the Institute for the Science of Teaching and Learning, is currently president of the Society for Text and Discourse and president-elect of the Society for Computers in Psychology.

• Adam Hahs, clinical assistant professor of psychology, is currently serving as president of the Arizona Association for Behavior Analysis.

“The elections of our colleagues to these leadership positions is a testament to the respect they’re accorded by their professional peers — not just for their exceptional scientific contributions but also for their good judgment and commitment to their disciplines,” said Steven Neuberg, Foundation Professor and chair of the Department of Psychology. “Their elections are also a testament to the breadth of our department’s contributions — together, these societies and divisions represent a significant portion of psychological science — and it’s wonderful to see that psychological scientists the world over recognize the high quality of research and professionalism represented throughout our department.”

Written by Kim D'Ardenne