Abstract
Research subject. The Karabash ore district is a unique structural zone in the Ural folded system, formed at the joint of the Magnitogorsk and Tagil depressions. The uniqueness of this zone is associated with its specific formation conditions: a Paleozoic copper pyrite belt with a width of about 8 km was squeezed between two blocks of ancient metamorphic rocks. This zone features a classic copper-pyrite deposit represented by steeply dipping ore bodies, which were initially characterized by a gentle dip. Elucidation of the primary geological structure and tectonic evolution of the district presents a relevant research task.Materials and methods. A geological cross section of the Karabash district was studied. Particular attention was paid to interactions between Paleozoic volcanic and sedimentary rocks and ultramafic bodies, whose age was determined by the method of zircon U–Pb dating.Results. The age of ultramafic bodies in the Karabash district was found to be 430–440 million years. Serpentinite blend (mélange) zones having a width of 60m were discovered in the sites of contact between ultramafites and host rocks. Regularities in the location of these zones in the eastern and western parts of the district make them suitable horizon markers for constructing a geological cross section of the Karabash ore district.Conclusions. It is established that the Karabash district is represented by a monocline synclinal fold formed by contraction of primary horizontal layers in the direction from east to west. The formation of the Zolotaya Gora golden deposit located in the eastern limb of the synclinal fold was associated with tectonic contraction processes.
Highlights
The Karabash ore district is a unique structural zone in the Ural folded system, formed at the joint of the Magnitogorsk and Tagil depressions. The uniqueness of this zone is associated with its specific formation conditions: a Paleozoic copper pyrite belt with a width of about 8 km was squeezed between two blocks of ancient metamorphic rocks
This zone features a classic copper-pyrite deposit represented by steeply dipping ore bodies, which were initially characterized by a gentle dip
Particular attention was paid to interactions between Paleozoic volcanic and sedimentary rocks and ultramafic bodies, whose age was determined by the method of zircon U–Pb dating
Summary
Для уточнения геологического строения Карабашского рудного района по профилю, который протягивается с запада на восток от восточного берега Аргазинского водохранилища до Уфалейского метаморфического комплекса, нами отобраны образцы вулканогенно-осадочных пород, петрографическое описание которых приведено ниже. Многочисленные линзовидные прослои сложены амфиболом и хлоритом, промежутки между которыми заполнены мелкозернистым агрегатом эпидота, кварца и мелкочешуйчатого хлорита. В некоторых линзах амфибол полностью замещен хлоритом, в других – агрегатной смесью, состоящей из мелких зерен эпидота, хлорита и кварца На контакте с амфибол-хлоритовыми сланцами, наблюдаются выходы эпидот-хлориткварцевых сланцев Мощностью 0.1–0.2 мм и слоев, сложенных мелкозернистым агрегатом слюды (биотита и мусковита, часто хлоритизированных), мелких зерен кварца и редких зерен эпидота. На контакте ультрамафитов с вулканогенно-осадочными породами наблюдаются зоны серпентинитового меланжа мощностью до 60 м Макроскопически меланж – это темно-серая, почти черная пятнистая порода, интенсивно будинированная с будинами более темного или более светлого цвета размером от 1–2 до 20–30 см. В шлифе порода представлена антигоритовым серпентинитом с гранобластовой, местами порфиробластовой структурой В шлифе порода представлена антигоритовым серпентинитом с гранобластовой, местами порфиробластовой структурой (рис. 10)
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