Paleo-temperature estimates from calcite rely on the fact that heavy isotopes form stronger bonds. The calcite found in the soil contains both the lighter isotopes of carbon and oxygen- 12C and 16O-as well as the rare heavier isotopes- 13C and 18O. Garzione worked in the southern Altiplano, collecting climate records preserved in ancient soils at both low elevations (close to sea level), where temperatures remained warm over the history of the Andes, and at high elevations where temperatures should have cooled as the mountains rose. Garzione and Leier (“ Stable isotope evidence for multiple pulses of rapid surface uplift in the Central Andes, Bolivia”) both focused on the bonding behavior of carbon and oxygen isotopes in the mineral calcite that precipitated from rainwater their results were similar. More recently, Garzione and Andrew Leier, an assistant professor of Earth and Ocean Sciences at the University of South Carolina, used a relatively new temperature-recording technique in two separate studies in different regions of the Andes to determine whether pulses of rapid surface uplift are the norm, or the exception, for the formation of mountain ranges like the Andes. Detachment of this dense anchor allows the Earth’s low density upper crust to rebound and rise rapidly. Garzione concluded that portions of the dense lower crust and upper mantle that act like an anchor on the base of the crust are periodically detached and sink through the mantle as the thickened continental plate heats up. Several years ago (2006-2008), Garzione and several colleagues provided the first estimates of the timing and rates of the surface uplift of the central Andes (“ Mountain Ranges Rise Much More Rapidly than Geologists Expected”) by measuring the ancient surface temperatures and rainfall compositions preserved in the soils of the central Altiplano, a plateau in Bolivia and Peru that sits about 12,000 feet above sea level. But that left two questions: How quickly have the Andes risen to their current height, and what was the actual process that enabled their rise? It’s been understood that the Andes mountain range has been growing as the Nazca oceanic plate slips underneath the South American continental plate, causing the Earth’s crust to shorten (by folding and faulting) and thicken.
“In geologic terms, rapid means rising one kilometer or more over several millions of years, which is very impressive.” “This study provides increasing evidence that the plateau formed through periodic rapid pulses, not through a continuous, gradual uplift of the surface, as was traditionally thought,” said Garzione.
America base one andes series#
In a paper published in the latest Earth and Planetary Science Letters, Garzione explains that the Altiplano plateau in the central Andes-and most likely the entire mountain range-was formed through a series of rapid growth spurts. New research by Carmala Garzione, a professor of earth and environmental sciences at the University of Rochester, and colleagues sheds light on the mystery. Scientists have long been trying to understand how the Andes and other broad, high-elevation mountain ranges were formed. New research points to a rapid surface uplift of mountain ranges
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