Metallogenic conditions, main ore controlling factors, chronology and metallogenic mode

1.Ore control factors.

1) The gold-bearing strata are dominated by the Early Paleozoic strata, and are dominated by the Middle Cambrian, Lower Ordovician and Upper Ordovician volcanic rock series, in which the abundance value of gold is generally higher than the abundance value of gold in the earth's crust, thus providing mineral material for the formation of gold deposits. Mineralization is dominated by the early and middle Caledonian periods.

2) Gold mineralization is closely related to Caledonian intrusive ultramafic rocks, mafic rocks, medium and acid rocks, and more than half of the gold deposits (points) are produced in the inner and outer contact zones between these intrusive rocks and surrounding rocks, and their mineralization has two effects: first, it provides thermal power for mineralization; The second is to provide mineral quality for mineralization.

3) Structural ore control is one of the most important factors, and the discovered gold deposits (points) are all produced in the fractured alteration zones formed by secondary faults, which are all channels for ore-bearing hydrothermal migration. It is also the ore-bearing space formed by gold mines.

4) There is no specificity in the ore-bearing surrounding rocks of gold deposits, and any strata and rocks in the early Paleozoic can be the site of gold occurrence; The alteration of the surrounding rock, which is closely related to gold mineralization, is mainly silicification, sericite, and pyrite mineralization, and there are also arsenite mineralization, yellow potash alumization, carbonateization, chlorite, etc., and the metal minerals are mainly pyrite, followed by sulfide minerals such as copper, lead, and zinc.

5) There are generally 1:200,000 geochemical anomalies near gold deposits (points), and the element assemblages are generally gold, arsenic, antimony, copper, lead, zinc, etc., and there is still placer gold distribution in the downstream valleys.

2.Prospecting direction.

1) The southern slope of the corridor focuses on the search for tectonic alteration rock-type gold deposits related to the Middle Cambrian volcanic rock series.

2) The central and western part of the Tuolai Mountains focuses on the search for tectonic alteration rock-type gold deposits related to ultramafic rocks.

3) The Osakashan area focuses on the search for gold deposits related to medium and acid ** incoming rocks and tectonic alteration rocks related to Upper Ordovician volcanic rocks.

3.There is a problem.

1) The Quaternary remnant slope deposits in the North Qilian Mountains cover a wide area, which is extremely unfavorable to geological work, and the current methods and means are difficult to achieve the goal.

2) The gold search work in the North Qilian Mountains only started in the 90s, and the degree of geological work is low, and most of the work is in the early stage of the survey, so there are still many geological problems that have not been solved. For example, what is the prospecting potential for gold in Precambrian strata? The gold deposits that have been discovered in the North Qilian Mountains are mainly small deposits and ore spots, so are there any large-medium gold deposits?

The metallogenic law and ore control factors of the discovered gold deposits (points) are low, and the research is superficial and rough, and the comparative research with typical gold deposits at home and abroad is insufficient. These problems still need to be solved and enriched by the layers of in-depth work of finding money.