Vesicular basalt paleoaltimeter: principles, methods and its applications

Paleoelevations would be useful to reconstruct the uplift history of highlands (especial the plateaus), and then could be better constrained the geodynamic processes of the orogens. Vesicular basalts can be used to determine paleoelevation at the time of eruption. The technique is based on the sizes of vesicles at the tops and bottoms of lava flows. The volumes of the bubbles depend on pressure. It is just the atmospheric pressure at the top of the flow, while it is the atmospheric plus hydrostatic pressure from lava overburden at the bottom of the flow. Since lava thickness can be measured in the field, the bubble size distributions can be measured in the lab, a simple relation can be solved for atmospheric pressure, and using the standard atmosphere elevation can be determined. The lava flows are 1-5 m thickness, and have been demonstrated simple emplacement history (without inflation or deflation). Although this method has been developed for many years, there are no reports in China. Therefore, we make a detailed introduction of this method, and then we discuss the possibility of its application in Tibetan Plateau and eastern China plateau.