AGE CONSTRAINTS AND METALLOGENIC PREDICTION OF GOLD DEPOSITS IN THE AKZHAL-BOKO-ASHALIN ORE ZONE (ALTAI ACCRETION-COLLISION SYSTEM)

IF 0.8 Q4 GEOCHEMISTRY & GEOPHYSICS

Geodynamics & Tectonophysics Pub Date : 2021-06-23 DOI:10.5800/gt-2021-12-2-0530

Y. Kalinin, K. Kovalev, A. Serdyukov, A. Gladkov, V. Sukhorukov, E. Naumov, A. Travin, D. Semenova, E. Serebryakov, E. D. Greku

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引用次数: 1

Abstract

We present new age constraints for igneous rocks and ore-metasomatic formations of the gold deposits in the Akzhal-Boko-Ashalin ore zone. In terms of their ore formation, these deposits correspond mainly to the orogenic type, which generally reflects specific metallogeny of the West Kalba gold-bearing belt in East Kazakhstan. Gold-quartz veins and mineralized zones of the gold-sulphide formation are confined to fractures feathering regional NW-striking and sublatitudinal faults. Their common features include the following: gold-bearing veinlet-disseminated pyrite-arsenopyrite ores that are localized in carbonaceous-sandy-schist and turbidite strata of different ages; structural-tectonic control of mineralization, numerous dikes of medium-basic compositions in ore-control zones; and the presence of post-orogenic heterochronous granite-granodiorite rocks, although their relation to gold-ore mineralization is not obvious. Igneous rocks of the study area have similar ages in a narrow range from 309.1±4.1 to 298.7±3.2 Ma, which is generally consistent with the previously determined age of granitoid massifs of gold-ore fields in East Kazakhstan. A younger age (292.9±1.3 to 296.7±1.6 Ma) is estimated for felsic rocks of the dyke complex. For the ore mineralization, the 40Ar/39Ar dating of sericite from near-ore metasomatites yields two age intervals, 300.4±3.4 Ma and 279.8±4.3 Ma. A gap between of the ages of the ore mineralization and the igneous rocks is almost 20 Ma, which may indicate that the processes of ore formation in the ore field continued in an impulse-like pattern for at least 20 Ma. Nevertheless, this confirms a relationship between the hydrothermal activity in the study area and the formation and evolution of silicic igneous rocks of the given age interval, which belong to the Kunush complex, according to previous studies. This interpretation is supported by reconstructed tectonic paleostress fields, showing that directions of the main normal stress axes changed during the ore mineralization stage, which is why the ore bodies significantly differ in their orientations. The above-mentioned data are the first age constraints for the study area. Additional age determinations are needed to further improve understanding of the chronology of ore-forming processes. Actually, all the features characterizing the gold mineralization of the Akzhal, Ashalin and Dauba ore fields, including the data on lithology, stratigraphy, structural tectonics, magmatism, isotope geochronology, mineralogy and geochemistry, can be used as criteria when searching for similar ore fields in East Kazakhstan.

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阿克扎-博科-阿什林矿带(阿尔泰吸合系统)金矿年龄约束及成矿预测

本文提出了阿克扎尔-博科-阿沙林矿带金矿床火成岩和交代层的新时代约束。这些矿床的成矿类型以造山型为主，总体上反映了东哈萨克斯坦西卡尔巴含金带的特殊成矿作用。金-石英脉和金矿化带局限于区域北西向和次向断裂的断裂。它们的共同特征是:赋存于不同时代的碳砂片岩和浊积岩地层中的含金细脉浸染型黄铁矿毒砂矿石;构造构造对矿化的控制作用，控矿带中基性岩脉较多;造山后异时花岗岩-花岗闪长岩存在，但与金矿成矿关系不明显。研究区火成岩年龄在309.1±4.1 ~ 298.7±3.2 Ma的狭窄范围内相似，与前人对东哈金矿区花岗岩体年龄的确定基本一致。岩脉杂岩的英质岩年龄较低(292.9±1.3 ~ 296.7±1.6 Ma)。矿化方面，近矿交代岩绢云母40Ar/39Ar定年得到300.4±3.4 Ma和279.8±4.3 Ma两个年龄区间。矿化年龄与火成岩年龄相差约20 Ma，表明矿田的成矿过程至少持续了20 Ma。尽管如此，这证实了研究区热液活动与给定年龄区间内属于库努什杂岩的硅质火成岩的形成和演化之间的关系。重建的构造古应力场支持了这一解释，表明主正应力轴方向在成矿阶段发生了变化，这是矿体取向差异明显的原因。上述数据是研究区域的第一个年龄限制。为了进一步提高对成矿过程年代学的理解，还需要进一步确定年龄。实际上，阿克扎尔矿田、阿沙林矿田和道巴矿田的岩性、地层学、构造构造、岩浆作用、同位素年代学、矿物学和地球化学等特征都可以作为在东哈萨克斯坦寻找类似矿田的标准。

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来源期刊

Geodynamics & Tectonophysics GEOCHEMISTRY & GEOPHYSICS-

CiteScore

1.20

自引率

14.30%

发文量

审稿时长

24 weeks

期刊介绍： The purpose of the journal is facilitating awareness of the international scientific community of new data on geodynamics of continental lithosphere in a wide range of geolchronological data, as well as tectonophysics as an integral part of geodynamics, in which physico-mathematical and structural-geological concepts are applied to deal with topical problems of the evolution of structures and processes taking place simultaneously in the lithosphere. Complex geological and geophysical studies of the Earth tectonosphere have been significantly enhanced in the current decade across the world. As a result, a large number of publications are developed based on thorough analyses of paleo- and modern geodynamic processes with reference to results of properly substantiated physical experiments, field data and tectonophysical calculations. Comprehensive research of that type, followed by consolidation and generalization of research results and conclusions, conforms to the start-of-the-art of the Earth’s sciences.