Bringing Up Baby (Mountains) in Western North America – #365papers – 2018 – 59

Yonkee and Weil, 2015, Tectonic evolution of the Sevier and Laramide belts within the North American Cordillera orogenic system: Earth-Science Reviews: v. 150, p. 531-593

What’s it about?

This paper is a wonderful, yet highly technical, summary of the tectonic events leading to the Rocky Mountains as we know them today. Continue reading

Migrating Marsupials of the Pleistocene – #365papers – 2018 – 44

Price, Ferguson, Webb, Feng, Higgins, Nguyen, Zhao, Joannes-Boyau, and Louys, 2017, Seasonal migration of marsupial megafauna in Pleistocene Sahul (Australia-New Guinea): Proceedings of the Royal Society B, v. 284: 20170785

What’s it about?

Seasonal migrations are seen in many large mammals. In modern animals, however, such migrations are not observed in marsupials. The authors put together geochemical data from rocks and fossil to show that the massive wombat-like extinct marsupial Diprotodon migrated seasonally as far as 100 km each way. Continue reading

Did the Chixulub Impact Make the Oceans Erupt More? – #365papers – 2018 – 43

Byrnes and Karlstrom, 2018, Anomalous K-Pg-aged seafloor attributed to impact-induced mid-ocean ridge magmatism: Science Advances, v. 4: eaao2994

What’s it about?

The Chixulub Impact is the event linked to the extinction of the dinosaurs. The authors here show that at the same time as the impact, ocean floor spreading increased for just a little while. They hypothesize that the seismic waves caused by the impact resulted in the mobilization of molten rock, leading to this increase in volcanic activity. Continue reading

Using Glass to Estimate Altitude – #365papers – 2018 – 37

Dettinger and Quade, 2015, Testing the analytical protocols and calibration of volcanic glass for the reconstruction of hydrogen isotopes in paleoprecipitation, in DeCelles, Ducea, Carrapa, and Kapp, eds., Geodynamics of a Cordilleran Orogenic System: The Central Andes of Argentina and Northern Chile: Geological Society of America Memoir 212, p. 261-276.

What’s it about?

Isotopes of oxygen and hydrogen from water can give us insights into the altitude at which that water fell to the ground as rain. Some of this water can become incorporated into volcanic glass (in ash), preserving the isotopic values of the original water. Continue reading

Did Bolide Bombardment Kill Life on Earth More Than Once? – #365papers – 2018 – 36

Grimm and Marchi, 2018, Direct thermal effects of the Hadean bombardment did not limit early subsurface habitability: Earth and Planetary Science Letters, v. 485, p. 1-8.

What’s it about?

The first billion years or so of Earth’s existence was marked by repeated bombardment of the planet by various asteroids, and even planetessimals. It is thought that this bombardment would superheat the Earth’s surface and kill any life that may have started to develop there. This study shows that, while the heating was extreme, there were still places that were protected from life-killing heat. Continue reading

Fossil Mammals and the Rocks that Contain them at Fossil Butte, Wyoming – #UREES270 – 2018

Gunnell, Zonneveld, and Bartels, 2016, Stratigraphy, mammalian paleontology, paleoecology, and age correlation of the Wasatch Formation, Fossil Butte National Monument, Wyoming: Journal of Paleontology, v. 90, p. 981-1011

What’s it about?

This paper contains a discussion of the mammalian paleontology at Fossil Butte National Monument, Wyoming. The authors examined and identified at least 46 species of fossil mammals from 29 localities within rocks of the Wasatch Formation at Fossil Butte. Using techniques of stratigraphy, the authors correlated all the localities in order from oldest to youngest. Further, they used the species present and clues from the rocks themselves to interpret the ancient environment in which the mammals lived. Continue reading

BREAKING! How Part of Canada got Stuck to Australia – #ScienceNews

This morning, while reading the newspaper, my eye caught this on the front page:

  Scientists chart land drift from 1.7 billion years ago  Doyle Rice  USA TODAY  Eons ago, the land Down Under wasn’t so far away after all.  Rocks recently discovered in Australia bear striking similarities to those found in North America, a study found. The sandstone sedimentary rocks the scientists uncovered are not "native" to present-day Australia but are common in eastern Canada.  The rocks were found in Georgetown, Queensland, Australia, which is roughly 250 miles west of Cairns in the northeastern part of the continent.  Scientists said one region of modernday Australia was once! attached to North America but broke away 1.7 billion years ago.  After drifting around for about 100 million years, the chunk crashed into what’s now Australia,  forming the "supercontinent" Nuna.  Researchers determined that when Nuna broke apart about 300 million years afterward, that chunk of land did not drift away. It instead became a new piece of real estate permanently stuck to Australia.  "This was a critical part of global continental reorganization when almost all continents on Earth assembled to form the supercontinent called Nuna," said study lead author Adam Nordsvan of Curtin University in Perth, A! ustralia. "This new finding is a key step in understanding ho! w Earth’s first supercontinent Nuna may have formed."  Nuna, sometimes referred to as Columbia, was one of several supercontinents that existed before the most well-known and recent one, Pangea.  The study was published in Geology.

Title reads: North American rocks migrated Down Under.
Photo from the Rochester Democrat and Chronicle.

This naturally piqued my attention.

So I found the original paper.

Nordsvan, Collins, Li, Spencer, Pourteau, Withnall, Betts, and Volante, 2018, Laurentian crust in northeast Australia: Implications for the assembly of the supercontinent Nuna: Geology, doi: https://doi.org/10.1130/G39980.1

Let me distill this in my own way… Continue reading

Carboniferous Glaciers of Chad – #365papers – 2018 – 1

Le Heron, 2018, An exhumed Paleozoic glacial landscape in Chad: Geology, v. 46, p. 91-94.

What’s it about?

Rocks of early Carboniferous age (mid-Mississippian, about 340 million years ago) in Chad show evidence of the passage of glaciers. Today, this part of the world is largely desert. This paper discusses the evidence for ancient glaciers and shows that they are not modern features of the wind. Continue reading

How Aluminum in Zircon Can Tell Us What Happened Billions of Years Ago – #365papers – 2017 – 150

#365papers for May 30, 2017

Trail, Tailby, Wang, Harrison, and Boehnke, 2017, Aluminum in zircon as evidence for peraluminous and metaluminous melts from the Hadean to present: Geochemistry, Geophysics, Geosystems, v. 18, p. 1580-1593.

What’s it about?

Zircon is a mineral that forms in igneous rocks. As the rocks erode away, the zircons often survive and can be mixed into younger rocks, including new igneous rocks. Here, the authors use the concentration of aluminum in the zircons to determine the type of igneous rock the zircon originally formed in. Continue reading