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A modeling case for high atmospheric oxygen concentrations during the Mesozoic and Cenozoic

Changes in atmospheric oxygen concentration over Earth history are commonly related to the evolution of animals and plants. But there is no direct geochemical proxy for O 2 levels, meaning that estimations rely heavily on modeling approaches. Show More Summary

Volatile dilution during magma injections and implications for volcano explosivity

Magma reservoirs underneath volcanoes grow through episodic emplacement of magma batches. These pulsed magma injections can substantially alter the physical state of the resident magma by changing its temperature, pressure, composition, and volatile content. Show More Summary

Triassic chrysophyte cyst fossils discovered in the Ordos Basin, China

Algae with siliceous structures are proposed to have originated following the Permian-Triassic extinction or even earlier, but there have been no robust fossil records to indicate their existence before the Jurassic–Cretaceous Periods. Show More Summary

Breathing more deeply: Deep ocean carbon storage during the mid-Pleistocene climate transition

The ~100 k.y. cyclicity of the late Pleistocene ice ages started during the mid-Pleistocene transition (MPT), as ice sheets became larger and persisted for longer. The climate system feedbacks responsible for introducing this nonlinear ice sheet response to orbital variations in insolation remain uncertain. Show More Summary

Paleo-Asian oceanic slab under the North China craton revealed by carbonatites derived from subducted limestones

It is widely accepted that the lithospheric mantle under the North China craton (NCC) has undergone comprehensive refertilization due to input from surrounding subducted slabs. However, the possible contribution from the Paleo-AsianShow More Summary

Mechanical amorphization, flash heating, and frictional melting: Dramatic changes to fault surfaces during the first millisecond of earthquake slip

The evolution of fault strength and behavior during the initial stages of slip plays an important role in driving the onset of instability and fault weakening. Using small-displacement triaxial experiments on quartz sandstone, this study...Show More Summary

Evidence of lateral thermomechanical erosion of basalt by Fe-Ni-Cu sulfide melt at Kambalda, Western Australia

The Fe-Ni-Cu sulfide ores at Kambalda, Western Australia, are interpreted to be the result of thermomechanical erosion of underlying rocks by the host komatiite lava flows. However, there is a long-standing argument about the extentShow More Summary

Testing the accuracy of genus-level data to predict species diversity in Cenozoic marine diatoms

Correlations between past biotic diversity and climate can inform humanity’s response to predictions of future global climate change, e.g., extinction risk with global warming. Paleodiversity studies, however, frequently use genera as a proxy for species diversity, a practice that has often been questioned. Show More Summary

Clockwise rotation of the entire Oman ophiolite occurred in a suprasubduction zone setting

The Oman ophiolite provides a natural laboratory for understanding oceanic lithospheric processes. Previous paleomagnetic and structural investigations have been used to support a model involving rotation of the ophiolite during formation at a mid-oceanic microplate. Show More Summary

Fault welding by pseudotachylyte formation

During earthquakes, melt produced by frictional heating can accumulate on slip surfaces and dramatically weaken faults by melt lubrication. Once seismic slip slows and arrests, the melt cools and solidifies to form pseudotachylytes, the presence of which is commonly used by geologists to infer earthquake slip on exhumed ancient faults. Show More Summary

Oregon team says life in Earth’s soils may be older than believed

Way before trees or lichens evolved, soils on Earth were alive, as revealed by a close examination of microfossils in the desert of northwestern Australia, reports a team of University of Oregon researchers.

The Hawai'i That Was: What the Worst Disaster You Can Think of? The Terror of Na Pali...

Wait, what? Terror? Na Pali? That place isn't terrifying, unless you have a fear of heights. It's one of the most beautiful places on one of the most beautiful islands in the world. What could be scary about it? Well...there's history, and geology. Show More Summary

Geologists discover how a tectonic plate sank

In a paper published in Proceedings of the National Academy of Sciences (PNAS) Saint Louis University researchers report new information about conditions that can cause the earth's tectonic plates to sink into the earth.

From the Road: Ocotillo, Coffee,Palo Verde, and The Turtle Mountains

After my overnight stop in the Whipples, I drove north, figuring I'd get a couple more photos of the Turtle Mountains. No, wait—from many previous trips, I knew the dirt road going out to the Turtles would be a good place to pull over...Show More Summary

High Grade Uranium & Copper Intercepts at the Canyon Mine , Coconino County, Arizona

Energy Fuels Inc. Canyon Mine property, 9 miles south of the South Rim of Grand Canyon, Arizona, is reporting high-grade uranium and copper intercepts. Uranium markets are floundering at about $20/pound, so the discovery of high-grade copper intercepts is an unlooked for economic boon. Show More Summary

A geologist’s reconnoiter of Piedmont

The city of Piedmont sits surrounded by Oakland, like an organelle in a cell. I’m undecided on which organelle it might be — a mitochondrion (powerhouse)? a nucleus (brain)? Maybe just a vacuole of well-controlled living. Whatever the case, it’s a good walking town if you happen to be fit. And geologically it’s fully part […]

Supermoon! Well, Really an Excuse to Be Out at Night on the Tuolumne River

The SUPERMOON is really a lot of unnecessary hype that doesn't really mean much. You'd think the gigantic moon would be grazing the outer edge of our atmosphere and causing supervolcano eruptions and earthquakes. I'm sure people will...Show More Summary

Links: Auriferous Gravels in CA

Here are a few links about the Au-bearing gravels of the California foothills and Sierra Nevada. (It's time to get this out of my drafts folder.) Early Tertiary Geology References - at Sierra Geology: where rocks meet the human environment...Show More Summary

Two Kinds of Falls Today in Yosemite Valley

There are two kinds of falls right now in Yosemite Valley. One comes from the time of year, and the other is a little bit unusual, the result of some powerful storms a few weeks ago. Fall in California is not like fall in other places. Show More Summary

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