How igneous rock can become sedimentary rocks?

Answer 1

An igneous rock at the earth's surface was once a long way under the earth in a magma chamber. Often the expression at the surface was a volcano, spewing out volcanic rock. The term for such activities on a large scale is called an orogeny. As time has gone by, there will have been uplift of the earth due to compression of the tectonic plates (there may have been many other geological activities in the meantime). During uplift there will be erosion due to weathering and tectonic activity. Eventually the magma chamber becomes exposed at the surface. these chambers can be very extensive, covering many hundreds of kilometres. The igneous rock inside the chambers are subject to the same weathering forces as the strata above them, once exposed. The rock breaks down (erodes), and tumbles due to gravity, to the lowest point possible, usually low areas of the ocean, off the continental shelves (but not always). Here it sits and becomes compacted with time due to accumulation of sediment above it, and often lowering due to tensions (pulling apart) of the tectonic plates.. As time goes by there will be another phase of uplift (among other geological activities that occur with time) and the result is a sedimentary rock exposed at the surface, with an igneous signature, usually called greywacke or sandstone. The different layers (strata) of the rock tell a story of the history of the rock. Geochemical analysis can pinpoint closely where the rock originated before being turned into a sedimentary rock. Fossils can provide relative dates of when the sedimentary rock was created, and radiometric dating can give accurate dates of when both the sedimentary and the igneous rock was created.

Answer 2

ingeous become sedimentary rocks after they undergo the process of weathering either mechanical, chemical, or biological.