VERTICAL ORE-METASOMATIC ZONALITY OF THE TOMINSK PORPHYRY COPPER ORE FIELD (SOUTHERN URALS, RUSSIA)

In the limits of the immiscibility region for the muscovite-paragonite system, the presence of homogeneous K-Na-mica [Na/(Na + K) = 0.64], i n association with paragonite and small amount of muscovite, was deter mined. All micas are assigned to the modification 2M(1). The formation temperature can exceed 320 - 380 degrees C, and the pressure is 0.8 - 1.2 kbar. Three-mica aggregate is observed in apodiorite mica-quartz metasomatites (frequently with carbonate and chlorite) of North Tomins k mesoabyssal porphyry copper and subvolcanic As-Cu-Zn-Ag-Au Bereznyak ovsk deposits located in the adjacent tectonic blocks of the Tominsk p orphyry copper ore field (Southern Urals). The presence of a unique th ree-mica association in the different types of deposits mentioned abov e indicates the genetic unity of these deposits, which represent vario us abyssal levels of a vertically extended porphyry copper column. In addition to the mentioned association of sodium micas, muscovite is wi dely distributed at the subvolcanic level. This is caused by the fact that the upward movement of juvenile primary sodic fluid flux is accom panied by an increase of the parameters K/Na, K/Rb, delta(18)O due to interaction with host rocks. At the final stage of subvolcanic deposit formation (T = 150 - 200 degrees C and P = 0.1 - 0.4 kbar), the argil lization of initial mica associations takes place with the development of hydromicas and disordered paragonite-smectites of modification 2M( 1).