Geology-Mineralogy and Isotope (O-D, S, Cu And Ar/Ar) Geochemistry of Sisorta High Sulfidation Epithermal Gold Deposit (Koyulhisar-Sivas)

Abstract

This study presents geological and geochemical features of gold deposit located in Sisorta area near Evliya Tepe, Guzelyurt village. The investigation area covers 42 km(2) land and located in 200 km NW of Sivas province in Sisorta. delta Cu-34 parts per thousand isotope values are ranging from-0,4 and parts per thousand parts per thousand 22, in Sisorta gold deposit. At the early stage of mineralization S isotope value number is light and later S isotope value shows heavy numbers. This is indicating that the S isotope was originated from magma and changed due to temperature variations in the last stages of the hydrothermal process. delta O-18 isotope values of gangue minerals are ranging from; parts per thousand 7,1 and parts per thousand 15,6 however, dD value is ranging from parts per thousand-77 to parts per thousand-25,3 Combining d18O with dD from Sisorta samples, demonstrates meteoric waters were important in the formation of the alteration silicate minerals analyzed. This is common in high sulfidation silicate alteration minerals. Ar-40/Ar-39 age dating is ranging from 78,85 +/- 0,94 Ma and 76,59 +/- 2,19 Ma as a plateau age and 78,25 +/- 0,42 Ma and 75,30 +/- 0,90 Ma as isochron age in K-alunite, 80,44 +/- 0,84 in hornblende minerals from unaltered andesitic volcanic rocks. This shows that hydrothermal gold mineralization is deposited 3 Ma later than the volcanic host rock eruption. delta Cu-65 parts per thousand values from copper-bearing minerals associated with Sisorta gold deposits are ranging from -5.502 parts per thousand to + 3.032 parts per thousand. The copper isotope values closest to the intrusions (deepest part of the system) do not show significant copper isotope variations (< 1 per mil), in contrast the upper parts of the system show large copper isotope variations and indicate enrichment of copper due to supergene processes.