Structural deformation and mineralization in the early Proterozoic Liaojitite suite, Eastern Liaoning Province, China

Abstract

The Liaojitite Suite, located in eastern Liaoning Province, China, formed in the eugeosyncline of an Early Proterozoic mobile zone. Structural deformation occurred during several orogenic episodes, especially during the second deformation of the third episode, the Luliang Orogeny, 1900–2000 Ma ago. Superposed dome-shaped structures and their unevenly distributed groups formed during the Luliang Orogeny constitute the principal tectonic style in the mobile zone. The tectonic style may be considered transitional in the evolution from an oval style in Archean granite-greenstone terrains to a linear style in Phanerozoic terrains. The superposed dome-shaped structures contain the Liaoji Granite in the cores, ringed successively by the Boron-bearing Series and the outer Turbidite Series. The simple appearances of the dome-shaped structures mask their complicated, multiply deformed nature, which is revealed by tracing their formation and evolution from primary volcanic domes to granitic diapirs and finally to superposed dome-shaped structures. The evolution of the superposed dome-shaped structures represents a change in crustal activity from simple shear to horizontal compression. Mineralization in the Liaojitite Suite was closely related to the three deformations of the Luliang Orogeny. Metallogenic elements were concentrated during the first deformation; physical re-emplacement of orebodies occurred during the second and third deformations.