 It was separated into the Longgang and the Langrim blocks in early Paleoproterozoic with an ocean in between.As the block started to separate, mafic and granitic melts intruded the crust 2.2–2 billion years ago and sedimentary and volcanic rock sequences were formed 2–1.95 billion years ago.For example, A-type granites, mafic and felsic igneous parent rocks of greenschist and lower amphibolite facies were formed.