Geochemical features and origin of Dandong granite

Abstract

New SHRIMP dating reveals that the previously-known Paleoproterozoic Dandong granitic complex is Mesozoic. SHRIMP dating to zircon oscillation rims yielded a crystallization age of 167-157 Ma of mica monzogranite, however the weighted mean age of inherited zircon in the zircon core is Paleoproterozoic. This paper mainly describes petrological and geochemical characters of Dandong Granite in order to discuss its origin and tectonic setting. The REE pattern of Dandong Granite shows negative Eu anomalies, Eu/Eu* = 0.59 - 1.41. There is distinct differentiation between light rare earth elements and heavy rare earth element. The granite shares all the features of trace elements common to the granite in the Andes-type continental margin. It shows that tDM of the pluton ranges from 2.30Ga to 1.93Ga, εNd (t) of the pluton has a range from -17.95 to -21.32. In the εNd (t) - t diagram, the source rock of Dandong Granite was mainly derived from Paleoproterozoic and medium to acid crustal rocks. Tectonic discrimination shows that it was formed in the continental marginal arc. In conjunction to Mesozoic tectonic setting of Dandong area, it is deduced that origin and emplacement of Dandong Granite are related to subduction of the Paleo-Pacific Plate to the Eurasia Plate.