Research team searches for climate change answers in the Andes

A time when Earth was nearly free of icy glaciers and alligators could be found crawling in northern Greenland has been giving scientists insight into what the planet could see in the not-too-distant future.

Tim White, a senior researcher in the Earth and Environmental Systems Institute in Penn State’s College of Earth and Mineral Sciences, along with Cecilia del Papa from the National University of Cordoba in Argentina, has been heading to the eastern Andes Mountains each year since 2006. This year, they were joined by colleagues from the University of Zaragoza in Spain.

There, the researchers sift through layers of ancient soils that were weathered from sediments in the basin and turned to rock before, during and after the time known as the Paleocene-Eocene Thermal Maximum, approximately 55 million years ago.

Well-preserved layers in the 10,000-foot-high landscape in Argentina offer not only a look at what was happening on Earth 55 million years ago, but also give scientists a chance to study a phenomenon that may be comparable to the warming conditions that are happening on Earth now.

To study that, the researchers collect and analyze “aridisols” — the ancient dryland soils similar to modern soils that developed in northern Mexico, Texas and other places where today 5 to 10 inches of rain a year is normal. The researchers are looking for answers about the period approximately 55 million years ago when conditions — and soils — abruptly switched from dry conditions to ones that were extremely wet and tropical, then back to dry again.

The aim is to get more precise dates for when those ancient soils formed along the banks of streams and rivers before the climate changed, moving both the sediments and streams in the Salta Basin of northwest Argentina around during this tropical period. Getting a more precise date stamp will allow scientists to get a narrower time frame for when and how fast the warming took place and offer insight into what to expect in the future.

Date stamping can be done for samples collected in places constrained on either side by a variety of means, including age dating of volcanic ash beds. But those volcanic ash beds aren’t found in the Salta Basin. Instead, White and the other researchers compare samples from the organic matter found in the Andes Mountains with samples from other areas that have already been date stamped.

Similar research has been done in other mid-latitude places, but the focus for this project is on the subtropical realm closer to the equator. Known as the Maiz Gordo Formation, the area of focus is a layer of rock literally preserved through time. The researchers have been going there, excavating rock samples that are then processed in a mass spectrometer at Penn State. The spectrometer produces the carbon isotope signature, which can provide a sort of fingerprint of the samples.

Those findings, in turn, provide more refined information for scientific modeling to see what turn the Earth is likely to take by providing data to simulate the Earth’s climate.

Source: Anne Danahy | Centre Daily Times

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