The Damanghor gold mineralization occurrence is located in north of Bardaskan, Khorasan Razavi Province, and Taknar zone. The geology of the area consists of Precambrian green sericite schist and metarhyolite, intruded by diabase. Mineralization in this area is in vein form with N50E stribe and 70NW dip and hosted by schist and metarhyolite with 300 meters length and 2 to 35 meters width. Disseminated and veinlet mineralization includes primary minerals of pyrite and chalcopyrite and secondary minerals such as covelit, malachite, azureite, hematite, goethite and limonite with quartz, sericite, and lesser clay minerals. Silicic-sericitic alteration is the most important alteration zone associated with mineralization. Based on rock samples taken from explorative trenches, gold anomalies range from 0. 3 to 12. 5 ppm, silver up to 30 ppm, copper up to 860 ppm, and zinc about 9252 ppm. Based on the evidence of host rock, the type and extent of alteration, structural control, shape and type of mineralization and primary minerals and geochemical anomalies, the occurrence of Damanghor gold mineralization is epithermal with intermediate sulfidation state that is related to hydrothremal derived from Cenozoic magmatic activities.

The selection of an appropriate estimation method is a crucial decision in resource estimation processes. There are multiple resource estimation methods of which the most important one is block modelling. Among the block modelling methods used for the estimation of gold resources, three methods have a broader application. These methods include Inverse Distance Weighting (IDW), Ordinary Kriging (OK), and Full Indicator Kriging (FIK). We compared the results of these three techniques and selected the most appropriate method for resource estimation of the Damanghor gold deposit. For this purpose, we prepared the geometric model of the deposit based on geological continuity and then, conducted the variography procedure to determine the grade continuity and the amount of gold resource. The dataset of the Damanghor area included eight diamond drilling boreholes and eight exploratory trenches comprising the grade results of 405 samples. The results show that FIK is the best method for resource evaluation of this case study. The OK method, however, is not suitable for this deposit. The IDW method provides reliable results when the drilling spacing is less than the variography range. This results can be used for the estimation of inferred resources when the geological continuity is appropriately determined.

Damanghor area is located northern Bardaskan, Khorasan Razavi province, and structurally, it is a part of Taknar zone. Geology of the area includes of Taknar metamorphosed sedimentary rocks and metarhyolite, which is intruded by diabasic rocks as stoke and dyke. The texture of metarhyolies is porphyry and contains of quartz and feldspar, whereas diabas has ophitic texture and contain plagioclas, pyroxene, and hornblend. Age of metarhyolite and diabas determined 550 Ma (Neoprotrozoic) and 8. 8 Ma (Miocene), respectively, using zircon U-Pb method. Metarhyolites have peraluminous nature and were formed at intracontinental rift. Low enrichment in LREE relative to HREE and Eu negative anomaly indicates the magma is formed at plagioclase stability depth. (87Sr/86Sr)i (0. 700712), (143Nd/144Nd)i (0. 511852), and ε Ndi (– 1. 51) values show source of magma was mantel or lower crust. Diabases have toleitic to metaaluminous nature and were formed at subduction zone. (87Sr/86Sr)i (0. 710527), (143Nd/144Nd)i (0. 512716), and ε Ndi (+1. 7) values indicate magma is drived from partial melting of metasomatized mantle wedge by released fluid of subducted slab, which is assimilated with continental crust. Taknar formation acidic Neoprotrozoic magmatism, which is formed at rift setting, associated with Miocene basic magmatism, which is formed at subduction zone, reveals an insight of tectonomagmatic conditions of Taknar zone in different times.