Abstract:

Two types of zircon, magmatic crystalline and captured fragment, are recognized in a syn-mineralization dyke(kjelsasite porphyry) sample collected from the Haigou gold deposit and used for zircon U-Pb dating. The averaged U-Pb age of the magmatic crystalline zircons of the sample is (132.4±1.5) Ma（n＝18，MSWD=0.48，Probability=0.96），indicating the formation age of the dyke. The upper and lower intersection ages of the zircons at U-Pb concordant plot are (2 460±29) Ma and (137±18) Ma respectively，probably representing the ages of the captured zircon fragments and forming age of the dyke. Comprehensive study indicates that gold mineralization in the Haigou gold deposit took place at about 132.4-128 Ma, a transitional period between the orogenic collision and postorogenic extension. It is suggested that the asthenospheric upwelling and related geological and mineralization processes are the main cause for the formation of the Haigou gold deposit. The Dahaigou pyroxene diorite stock at the southeastern corner of the mine is thought to be coeval and cogenetic with the syn-mineralization dykes in the mine and its age gives the upper limit of the ore forming age.

Key words: Haigou, syn-mineralization dykes, zircon LA-ICP-MS U-Pb dating, metallogenic model, gold deposits, Jilin Province