气孔玄武岩古高程计:原理、方法及应用

古高程可以重建高山地区(尤其是高原)的隆升历史,可以更好地约束造山带的地球动力学过程.气孔玄武岩古高程计是通过熔岩流顶部和底部标准气孔体积比计算出古大气压,进而计算古高程的方法.该方法的研究对象是厚度为1～5m的且具有简单侵住历史的玄武质熔岩.高原隆升之前、期间和后期喷发的熔岩均可应用该方法.尽管该方法已经趋于成熟,但是国内还没有任何报道.对其基本原理、研究方法与应用做了详细的综述,并探讨了该方法在青藏高原和中国东部高原应用的潜力.

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 atthe bottom of the flow. Since lava thickness can be measured in the field, the bubble size distributions can be measured in the lab, asimple relation can be solved for atmospheric pressure, and using the standard atmosphere elevation can be determined. The lava flowsare 1-5 m thickness, and have been demonstrated simple emplacement history (without inflation or deflation). Although this methodhas been developed for many years, there are no reports in China. Therefore, we make a detailed introduction of this method, andthen we discuss the possibility of its application in Tibetan Plateau and eastern China plateau.