Structural deformation of the Shilu iron ore deposit in Hainan, southern China, and its relationship with the formation and enrichment of iron-polymetallic metals

Shilu iron ore deposit, which is situated at the western Hainan Province of southern China, has been reputed as the biggest hematite-rich ore deposit in Asia. The formation and location of the deposit have close relationship with folds and their incidental shear and plastic flow structures. Based on tectonic styles and deformation mechanism of the orebodies and their host rocks, the strongly structural deformation in the studied ore deposit can be classified into two phases, which are D1, the early regional-scale synclinorium formation stage and D2, the late fold superimposition and concomitant shear deformation stage. The latter (D2) can be further divided into three uninterrupted stages of D2a, D2b and D2c, and represents dynamic transformation from ductile-brittle shear and high-T(temperature) plastic flow to low-T brittle fracture. The ore-bodies are strictly controlled by the NW-SW trending synclinorium and the superposed folds which were formed due to superposition of the late NE-NNE trending transversal folds on the early synclinorium, whereas the ductile-brittle shear and concomitant high-T plastic flow were main mechanisms for formation of the hematite-rich ore-bodies. Iron-rich ore bodies in the Shilu iron ore deposit often can be found along the synclinorium axis, especially in the positions of the forementioned superposed synclines.