Тезисы международной конференции
Abstracts of International conference
Fluidizate-explosive activity and ore-bearingness of Volyno-Podol'skiy pericraton
of the East-European platform
Ivan Franko National University of Lviv, Lviv, Ukraine; Yatsenko1941@list.ru
Protons and tectons of alkaline specialization have been formed in the basement of the Volyno-Podol'skyi pericraton, as well as in the Ukrainian shield. Due to fluidizate-explosive processes which have taken place during the activation stages from Early Proterozoic to Neogene the displays of diamonds, noble, rare and other metals, and non-metallic minerals have been formed in the basement and cover.
Pericraton has a two-storey structure – the submerged crystalline basement and complex cover (Upper Precambrian and Phanerozoic deposits). Slope of the craton to the west of the Ukrainian shield submerges by scarps to the depth of 1,5–4,0 km which has been defined by boring (Geotectonics..., 1999). Structure of basement and, partly, of cover in a certain measure correlates with the Kirovograd block of the Ukrainian shield. It is predetermined to a great extent by the influence of fluidizate-explosive constituent. Processes of pipes and dykes with proper breccias forming reflect mantle “breathing”, promote ore-forming processes; they spread all over the crystalline basement and cover of first protoplatforms during activation stages in Proterozoic. Pridnestrovskiy and, to the north, Volynskiy protons and also Polesskiy tecton have been formed.
Early formations contain metamorphic, some magmatic and fluidizate-explosive rocks of alkaline specialization, as, for example, in the better studied Kirovograd block of the shield. In particular, Devonian (Rovnenskoe) and Cretaceous–Palaeogene (Kirovogradsko-Smelyanskoe) fields of pipes and dykes of lamproitic type have been discovered there, as well as Proterozoic kimberlites with fine diamonds. Rare-metal metasomatites (fenites), manifestations of titan, manganese, gold, coloured and rare metals (Zr, U, Ta, Nb, Li, Be etc.), and also non-metallic raw material are connected with sub-alkaline massifs and pipes. Stratified manifestations of bauxites, graphite, corundum, bentonites etc. are arranged for explosive structures in the basement and cover. Alkaline metasomatic processes have been replaced by hydrothermal activity at the regressive stage. Manifestations of gold and associating elements have been formed.
Basement of Archean Podol'skiy block adjoins pericraton easterly. Proterozoic clastic protrusions (Goloskovskaya etc.) and dykes have been discovered there, for which titanic, phosphatic, noble and rare-metal specialization is characteristic. It is the special, clastic, deep-seated type of manifestations connecting with fluidizate-explosive processes.
All these facts in a certain measure serve as a model for prognostication of ore-bearingness of deeply submerged and that is why not enough studied basement of Volyno-Podol'skiy pericraton. Young and thick cover, through which fluidizates and their derivates were broke, has been saved better as compared to the shield. Deep material partly stayed too long at different levels of cover, broke through to the surface, forming the manifestations of useful minerals of the proper type. The stages of activation showed up during Paleozoic, Mesozoic and, especially, Cretaceous; more late manifestations also are marked.
Zone of joining of shield and pericraton has an independent importance for ore-forming processes. Podol'skiy trough with trap formation and Proterozoic granitoids, sub-alkaline and alkaline-ultrabasic rocks (Antonovskiy and other massifs) are arranged for this zone. Fluidizate-explosive rocks of Later Proterozoic and Phanerozoic stages of activation have been discovered (Lyadovskaya and other structures) (Radzivill et al., 1985). Non-ferrous and rare metals, apatite, barite, fluorite and glauconite are connected with them.
We'll note that stratigraphic complexes of the slope zone (Mogilyov-Podol'skaya, Volynskaya series), which today are considered Vendian, in 1950th were Paleozoic due to paleontologic data. We discovered that different-age sedimentary and stratified explosive rocks (Vendian, Paleozoic and Cretaceous) and also the rocks of the proper explosive structures are united in some sections. Saponites, clastites, scoriae are exposed at the north segment of the joint zone (between Izyaslav and Slavuta, on the Goryn' right river bank, in the villages of Putrintsy and Tashki). These rocks are connected not only with Vendian but also with Cretaceous, Paleogene and Neogene stages of activation. The minerals-satellites of diamond have been found in these rocks (Diamond-bearing.., 2002).
The rocks of central, the most submerged part of pericraton (Paleozoic and younger) also have signs of the fluidizate-explosive influencing. Breccias, alkaline metasomatites and veins of hyaline formations of sub-alkaline composition have been exposed by wells (Geotectonics..., 1999). Explosive activity may participate in the forming of Devonian Pelchinskaya structure. We found out fluidizated calcareous breccia of Mezo-Cenozoic in the deposits overlapping it.
Minerals-satellites of diamond (pyropes which genesis is not already found out) and other minerals are quite often in modern alluvial deposits. Some scientists suppose that they have been transferred from preceding collectors, but more probably, that they are the derivates of explosive structures. We discovered fluidizate-explosive rocks, which usually are interpreted as tuffs of problematic volcanoes, in Neogene deposits of Pre-Carpathians region: we found out garnets and other diamond satellites in the alluvium of Vishenka-river (village of Dubrinichi). They are from coarse-grained band in Anthropogen clays. Higher the band of sands and loams with semi-rounded pebble and boulders (which are of glacial origin, as usually consider) occurs. We consider that these rocks are local: they have been transferred from the basement by explosive structures, which were the “microsounds” into the Earth's depth.
Volynian part of the pericraton contains basaltic formations, traps with the native copper deposits. Possibly, copper relates to more late hydrothermal processes in explosive structures.
Belonging of Volyninan region basement to the protons and tectons, as consider (Yanse, 1992), reduces prospects of its diamond-bearingness. Nevertheless, the fragments of kimberlites and fine diamonds have been found here (Yatsenko et al., 2005). Cover deposits contain material of explosive structures. The fragments of Upper Cretaceous rocks (limestones, marls, explosive breccias of different composition) have been discovered in near-surface sands. The lenses of fluidizated carbonate breccias (K2) with the debris of basement deposits have been discovered on the hill – in sand quarry of Rostan'. Disparity of their Cretaceous age and their location can be explained by cutting the deposits from the ledges of Upper Cretaceous carbonate series by glacier and burial in the sands of glacial origin. Semi-rounded pebbles of the region basement rocks (granitoids of Korostenskiy complex, red Ovrouch sandstones, lamproites, phosphorites etc.) have been found in Cretaceous breccias as well as the minerals-satellites of diamond. Pebbles, clasts and minerals are worn-out and ovaled. It is connected, in our opinion, with their moving to the surface through the channels of fluidizate-explosive system. They were not brought by glaciers from Scandinavia. More probably that local glaciers could participate in treatment of material.
Approximately the same composition has more rare debris in the sandy deposits of some modern lakes. We discovered fine diamonds, their minerals-satellites and particles of scoriae and glasses in the modern sands of Shatsk Lakes region. Similar fluidizate-explosive rocks have been found in the proper deposits of Byelorussia.
The signs of fluidizate-explosive activity and ore-forming in the south-west pericraton of the East-European platform are traced from Proterozoic to Neogene. Processes often have an alkaline orientation that influences on the specific of region ore-bearingness. Foremost, it is connected with the problem of lamproitic type diamonds, decided on this territory. Primary, not redeposited placers in collectors of Cretaceous and more late time can be here.
The south part of pericraton – Pridobrudzha, where we have described the lamproites, also has the similar features. In addition, as is generally known, an alkaline orientation is inherent to the explosive structures of Byelorussia.
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