玲珑金矿田花岗岩中韧性剪切带与成矿的关系

THE RELATION OF DUCTILE SHEAR ZONES TO MINERALIZATION IN THE LINGLONG GOLD OREFIELD

珑玲燕山期交代型花岗岩,是在构造活动的驱使下,由共存重熔岩浆交代胶东群变质岩生成的壳源花岗岩,成岩作用是在可塑性准固体状态下进行的。伴随底辟侵位广泛形成韧性剪切带,发育有各种塑变、应变结构和糜棱岩化。随着岩体温度和可塑度的降低,相继发生脆性断裂,往往叠加在韧性剪切带之上。这种构造叠加部位为矿液造成良好的通道和富集部位。

The Linglong Yanshanian metasomatic type granite is a orust-source granite formed by metasomatism of metamorphic rocks of Jiaodong Group under the driving force of structural activity and the action of coexistent remelted granite magma, and the Linglong gold deposit occurs at the northeastern end of this rock body. Faults are quite developed in the rock body: the NEE-NE trending fault system, which experienced strong ductile shearing at the early stage and brittle fracturing at the late stage, is the major ore-controlling and ore-hosting structure; the NNE-and NW-trending faults, belonging to brittle faults, were formed comparatively late and frequently destroyed orebodies. The evolution of faults is obviously characterized by stages. When the rock body underwent diapiric emplacement, the granite was in a plastic quasisolid state and formed a series of ductile shear zones as a result of compression, thus developing extensively plastic deformation flow, folds, crenulation, kinks, subgrains, pressure solution, flame-like rheological quartz aggregate crystals, recrystallization, abnormal extinction and mylonitization. With the falling of temperature and plasticity of the rock body, brittle faults occurred in succession under the same stress field, and were frequently superposed on the ductile shear zones. Under the strong dynamothermal action, metallogenic substances of the source rock were activated and transferred. Ductile-brittle fractural shattered zones obviously control the formation and spatial distribution of gold deposits; the superposition localities of the ductile shear and the brittle fault seem especially favorable for ore formation, and are thus important criteria and the best positions for ore prospecting.