1. College of Earth Sciences��Jilin University��Changchun 130061��China; 2. Shandong Gold Mining (Linglong) Co����Ltd����Zhaoyuan 265419��Shandong��China

Jiuqu gold deposit is a quartz vein- altered type gold deposit��located at Zhaoyuan- - Pingdu metallo- genic belt in the northwest of eastern Shandong gold concentration area�� The igneous rocks exposed in the deposit are mainly composed of biotite monzogranites��light fine- grained granites and porphyry- like granodiorites�� Four sta- ges of mineralization were identified��which are quartz- pyrite stage��pyrite- quartz stage��quartz- polymetallic sulfide stage and carbonate stage�� The study of fluid inclusion shows that CO₂ - bearing three- phase inclusions (type I)�� gas- liquid two- phase inclusions (type II) and pure CO₂ inclusions (type III) developed in quartz of the main min- eralization�� From early to late stage the mineralization fluids demonstrate from low- medium (301�� �� 365��) to medium- high (200�� ��256��) in temperature��and CO₂ changes from rich to poor in value��and gnerally have the charactes of low salinity (3. 53% �� 10. 74% NaCleqv) and density (0. 55 �� 0. 96 g·cm^-3 )��with metallogenic pressure and depth of 75 ��129 MPa and 7. 04 ��9. 46 km��respectively�� In addition��mineralization fluids have δ¹⁸O (0. 9 ×10^-3 ��7. 1 ×10^-3 ) and δD ( ��51 ×10^-3 �� ��64. 2 ×10^-3) magma and ore- hosting rock in the up- welling process�� It is suggested that mantle- derived fluids contribute to mineralization�� And the Jiuqu gold deposit should be the mesothermal vein- type gold deposit in genesis��