the Phanerozoic. The Eastern Block is defined by high heat flow, thin lithosphere and a lot of earthquakes. It experienced a number of earthquakes with a magnitude of over 8 on the Richter scale, claiming millions of lives. The thin mantle root, which is the lowest part of lithosphere, is the reason for its instability. The thinning of the mantle root caused the craton to destabilize, weakening the seismogenic layer, which then allows earthquakes to happen in the crust. The Eastern Block may once have had a thick mantle root, as shown by xenolith evidence, but this seems to have been thinned during the Mesozoic. The Western Block is located in Helanshan-Qianlishan, Daqing-Ulashan, Guyang-Wuchuan, Sheerteng and Jining. It is stable because of the thick mantle root. Little internal deformation occurred here since Precambrian. Geology The rocks in the North China craton consist of Precambrian (4.6 billion years ago to 539 million years ago) basement rocks, with the oldest zircon dated 4.1 billion years ago and the oldest rock dated 3.8 billion years ago. The Precambrian rocks were then overlain by Phanerozoic (539 million years ago to present) sedimentary rocks or igneous rocks. The Phanerozoic rocks are largely not metamorphosed. The Eastern Block is made up of early to late Archean (3.8-3.0 billion years ago) tonalite-trondhjemite-granodiorite gneisses, granitic gneisses, some ultramafic to felsic volcanic rocks and metasediments with some granitoids which formed in some tectonic events 2.5 billion years ago. These are overlain by Paleoproterozoic rocks which were formed in rift basins. The Western Block consists of an Archean (2.6–2.5 billion years ago) basement which comprises tonalite-trondhjemite-granodiorite, mafic igneous rock, and metamorphosed sedimentary rocks. The Archean basement is overlain unconformably by Paleoproterozoic khondalite belts, which consist of different types of metamorphic rocks, such as graphite-bearing sillimanite garnet gneiss. Sediments were widely deposited in the Phanerozoic with various properties, for example, carbonate and coal bearing rocks were formed in the late Carboniferous to early Permian (307-270 million years ago), when purple sand-bearing mudstones were formed in a shallow lake environment in the Early to Middle Triassic. Apart from sedimentation, there were six major stages of magmatism after the Phanerozoic decratonization. In Jurassic to Cretaceous (100-65 million years ago) sedimentary rocks were often mixed with volcanic rocks due to volcanic activities. Tectonic evolution The North China Craton experienced complex tectonic events throughout the Earth's history. The most important deformation events are how the