Author: John BershawPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
"High topography significantly affects climate and atmospheric circulation, often separating areas of intense precipitation from relatively arid rainshadows inland. Temporal variations in climate on high plateaux have been inferred from both rocks and ice and may be related to changes in global climate, local atmospheric circulation, and/or changes in surface elevation. Constraints on how and when surface topography was generated not only provide insight into the relationship between high plateaux and climate, but help us distinguish between different geodynamic mechanisms responsible for their formation. The following research employs multiple techniques across the Andean Plateau, the Pamir, and Tibetan Plateau, to better understand both the tectonic evolution of high plateaux and how they affect climate and atmospheric circulation, particularly in continental settings. The Andean Plateau in South America is the second highest and most extensive topographic feature on Earth. Paleoelevation constraints from fossil leaf physiognomy and stable isotopes of sedimentary carbonate suggest that significant surface uplift of the northern Andean plateau, on the order of 2.5 ± 1 km, occurred between ~10.3 and 6.4 million years ago (Ma). South American teeth from modern and extinct mammal taxa spanning from the Oligocene (~29 Ma) to present were collected as they preserve a record of surface water isotopes and the type of plants that animals ingested. Previous studies have shown that the isotopic composition of oxygen [... characters removed] in modern precipitation and surface waters decreases systematically with increasing elevations across the central Andes. Results from high elevation sites show substantially more positive [... characters removed] values for late Oligocene tooth samples compared to