Origin and Emplacement of Archean Ophiolites of the Central Orogenic Belt, North China Craton

The Dongwanzi ophiolite is one of the largest well-preserved greenstone belts in the Central Orogenic belt that divides the North China craton into eastern and western blocks. More than 1000 other fragments of gabbro, pillow lava, sheeted dikes, harzburgite, and podiform–chromite bearing dunite occur as tectonic blocks (tens to hundreds of meters long) in a biotite–gneiss and BIF matrix, intruded by tonalite and granodiorite, in the Zunhua structural belt. The North China craton is one of the world's most unusual cratons in that it had a thick tectosphere developed in the Archean, which was present through the Ordovician as shown by deep xenoliths preserved in Ordovician kimberlites. The largest well-preserved sections of the Dongwanzi ophiolite are located approximately 200 km NE of Beijing in the northeastern part of the Zunhua structural belt, near the villages of Shangyin and Dongwanzi. The upper part of the Dongwanzi ophiolite consists of pillow lavas, pillow breccias, and interflow sedimentary rocks including rare chert, banded iron formation, and metapelites.