Stratification and Cross-Stratification in the Layered Anorthosite of Chimalpahad, Khammam District, Andhra Pradesh, India

The Chimalpahad layered anorthosite at the border zone of Archaean supracrustal rocks of Khammam and Eastern Ghats shows normal stratification predominantly in the form of rhythmic layering and sometimes in the form of zebra layering. Cross-stratification showing clear truncation by the top normal stratification from the layered anorthosite of Chimalpahad is one of the very few such occurrences reported from layered rocks of the world. The cross-stratification could have originated due to flow of magma current and fluctuation in its velocity across the floor of the magma chamber. The structure is useful as a way-up criterion.