Sihayo Gold Limited (ASX: SIH) has announced encouraging gold intercepts including 17 m @ 1.14 g/t Au and 4.2 g/t Ag from the first hole of the diamond drilling program at the Hutabargot Julu prospect in the northern block of the PT Sorikmas Mining Contract of Work, North Sumatra, Indonesia.
SIH reported that the assay results for the first of 22 planned drill holes at Hutabargot Julu demonstrated strong gold mineralisation from surface, which included 17 m @ 1.14 g/t Au and 4.2 g/t Ag, and deeper mineralisation, which included 17 m @ 1.21 g/t Au and 7.6 g/t Ag from 180 m.
The company said that these results and on-going core logging show the presence of intense epithermal alteration and mineralised veining to a depth of at least 100-150 m with potential for mineralised veins extending to greater depth.
SIH said that the results support the potential for near surface, bulk-tonnage oxide gold deposits, and more discrete higher-grade gold vein zones within a large mineralised epithermal system.
The company said that a total of five holes and 1,115 m of the 5,500 m program has been completed to date, with further results expected to be available from early December. Sihayo said that it is well-funded for this exploration program and further activity on the Contract of Work.
Sihayo gold project
The Sihayo-Pungkut 7th Generation Contract of Work is highly prospective for gold and copper mineralisation. The Sihayo Gold Project is at an advanced stage and the company has active regional exploration programs.
The prime exploration targets are prospects identified by historic work along two mineralised trends, Sihayo-Hutabargot and Sihayo 3-4-5, which comprise the Sihayo gold belt. The Sihayo gold belt is located on fault-strands from an extensional dextral jog in the Trans Sumatran Fault Zone (TSFZ).
Drilling at the Hutabargot Julu
The company had recently commenced a planned 22-hole (5,500 m) diamond drilling program using two man-portable rigs owned and operated by PT Indodrill Indonesia, at the Hutabargot Julu prospect located in the northern block of the PT Sorikmas Mining Contract of Work, North Sumatra, Indonesia.
The program was planned on the large Hutabargot Julu epithermal gold-silver target, located approximately 6 km southeast of the proposed Sihayo Starter Project site. The planned drill holes were located across the northern part of a 3.5 km x 3.0 km gold-soil geochemical anomaly highlighted extensively altered and mineralised volcanic rocks that have been largely untested by drilling to date. The previous drilling done by Sihayo at Hutabargot Julu during 2010-2013 was focussed mainly on the southern edge of this anomaly.
The broad distribution of strongly anomalous gold results detected in soils from a previous survey at Hutabargot Julu suggested prospectivity disseminated gold sources in the bedrock.
The aim of the initial program by SIH was to test the potential for a large gold resource similar to the Martabe gold-silver deposit, located about 80 km northwest of the Sihayo Project. Martabe and the Sihayo Project, which includes the Hutabargot Julu gold-silver target, all lie within the same highly prospective mineral belt of North Sumatra.
The company reported that a total of 1,115 metres in 5 holes for the Hutabargot Julu prospect has been completed to date.
High-grade results reported from the first DD hole
SIH announced that encouraging gold intercepts were returned in assay results received for the first hole completed in the program, HUTDD057.
The company said that the hole HUTDD057 returned gold intercepts in strongly altered and veined volcanic rocks including 17 m at 1.14 g/t Au and 4.2 g/t Ag from 0 m (surface), including 0.5m @ 8.63 g/t Au and 2.8 g/t Ag; 3 m at 0.46 g/t Au and 5.6 g/t Ag from 32 m; 9 m at 0.51 g/t Au and 3.5 g/t Ag from 96 m; 9 m at 0.86 g/t Au and 4.0 g/t Ag from 135 m; and 17 m at 1.21 g/t Au and 7.6 g/t Ag from 180 m, including 1 m @ 7.64 g/t Au and 48.2 g/t Ag.
The company reported that the 17 m at 1.14 g/t Au and 4.2 g/t Ag intercept was returned in 3 – 4 metres of residual soil overburden and then completely oxidised bedrock of thinly quartz-chalcedony veined, intensely limonitic altered volcaniclastic rock. Anomalous gold ranging from 0.1 to 0.3 g/t Au continued from 17 m until the base of complete oxidation at about 49 m depth downhole and is associated with uniformly anomalous arsenic geochemistry.
SIH noted that the hole intersected mottled grey-white, intense clay-sulphide altered volcaniclastic rocks below the base of oxidation until approximately 196 m downhole, and returned significant gold-silver intercepts in multiple zones of epithermal quartz-chalcedony-sulphide veining.
The reported gold-silver intercepts of 9 m at 0.51 g/t Au and 3.5 g/t Ag, 9 m at 0.86 g/t Au and 4.0 g/t Ag, 17 m at 1.21 g/t Au and 7.6 g/t Ag are associated with disseminated to locally semi-massive sulphide mineralisation (2-5% pyrite-marcasite) in the epithermal veins. The company said that intensely altered wallrock intersected between the mineralised epithermal vein zones also returned anomalous but lower grade gold and silver results averaging around 0.1-0.15 g/t Au and 1-2 g/t Ag.
The hole terminated in propylitic altered porphyritic andesite hosting narrow quartz-chalcedony-adularia veins that contain traces of disseminated sphalerite-galena mineralisation with locally elevated gold and silver results.
Potential for bulk-tonnage disseminated gold
The company said that the results of the first hole have highlighted significant gold mineralisation in a previously untested area of the Hutabargot Julu prospect and support the potential for bulk-tonnage disseminated gold and discrete gold vein zones within a large mineralised epithermal system.
The company expressed optimism that the exact nature of the mineralised system would be better defined when additional drilling information and assay results become available.
The company said that the distribution and continuity of the gold mineralisation will be better defined in follow-up drilling programs after the current scout program has been completed and the results fully evaluated.
Sihayo’s Executive Chairman Colin Moorhead said: “This is an encouraging result given it is the first hole of a broad-spaced scout drilling program that is designed to test a large gold-soil geochemical anomaly with associated anomalous geophyisical features for potential near-surface bulk-tonnage oxide gold deposits and for more discrete higher-grade narrow gold vein targets.
Similarly ecouraging intercepts received from earlier drilling done by the Company in 2010-2013 on the western and southern edges of this large 3.5 km by 3 km prospect area, combined with this latest result, confirm the potential for a significant gold discovery at Hutabargot Julu.
We are in the early stages of our current drilling program. Our aim in this initial program is to quickly assess large areas of the prospect that have not been previously drill tested and then to assess the results and focus on specific parts of the prospect with more targeted follow-up drilling to delineate potential for near-surface gold resources. This initial drilling result and the extent of the alteration and veining reported from our site geologists in subsequent holes completed are highly encouraging. The new geological information and supporting assay results provided in each scout hole will set a firm base to plan and implement our on-going drilling evaluations at Hutabargot Julu.
We look forward to announcing additional encouraging results over the next few months as we continue to receive and evaluate data from the current program.”