Generation and evolution of Vortex array with variable-ratio lateral-shearing interferometry

Different from the method by plane-wave interference, here an efficient approach is proposed to generate optical vortex array (VA) based on lateral-shearing interferometer (LSI), in which the evolution from light spot array to VA can be observed by continuously variable shear ratio in a certain range. VAs with topological charge 2 and 1 are simulated by software GLAD and proved to be effectiveness through optical experiment. Theoretical analysis and experimental results show that when the shear ratio approaches to zero, we can stably obtain a vortex array with high density and variable topological charge.

LA-ICP-MS U–Pb Dating of Cenozoic Rutile Inclusions in the Yuanjiang Marble-Hosted Ruby Deposit, Ailao Shan Complex, Southwest China

Among the marble-hosted ruby deposits in the Himalayan tectonic belt, which yields the highest-quality rubies in the world, the Yuanjiang deposit is the only economically viable one located in China. More attempts are necessary to put constraints on the ore-forming age of these marble-hosted ruby deposits. Here, we dated rutile inclusions in the Yuanjiang rubies using the LA-ICP-MS U–Pb method, which yielded a lower intercept 206Pb/238U age of 20.2 ± 1.2 Ma on the Tera-Wasserburg plot, close to the 22.5–22.2 Ma 40Ar/39Ar ages of phlogopite from the ruby host matrix assemblage. Our U–Pb rutile age put a constraint on the cooling history of the Yuanjiang rubies deposit. The new rutile age is consistent with our previous model that shows the ca. 28–22 Ma left lateral shearing plays an important role in transporting the ruby deposit toward the surface. This study provides the first example of in-situ U–Pb dating of rutile in the Himalayan tectonic belt, demonstrating the great potential of U–Pb rutile geochronology for Cenozoic mineral deposits.