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Magnetotelluric sounding evidence of development of nappes in the Tuolai Sag, Yin-E Basin

Penghui Zhang, Hui Fang, Xiaobo Zhang, Yaoyang Zhang, Haihong Xu, Yan Peng, Yongzhen Yuan

Acta Geophysica

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2020

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Vol. 68, no. 1

91--104

EN

To explore the tectonic framework and features of stratigraphic distribution in the Tuolai Sag, Yin-E Basin, a 47-km-long magnetotelluric (MT) sounding measurement was performed around Well MAZD1 in the sag. During feld data acquisition, a remote reference technique was used to ensure data quality, with apparent resistivity and phase curves of all measuring points obtained using the Fourier transform, power spectrum selection, robust estimation and other methods. After MT data processing, dimensionality analysis and the degree of two-dimensional deviation indicated that the study area had the dimensionality needed for two-dimensional inversion. The major electrical axis in the sag was determined, using a multipoint–multifrequency point statistical imaging technique, to be in the WNW direction. Within the constraints of the resistivity log data for Well MAZD1, inversion results for TE and TM models were compared, after which the TM model, which corresponded well to geological conditions, was selected for conducting the nonlinear conjugate gradient method inversion and a reliable resistivity model was fnally obtained. Based on regional petrophysical properties, resistivity logging, and near-well bathymetric data, the electrical characteristics of diferent formations within the sag were obtained and a set of low-resistance clastic rock identifed in the lower Carboniferous strata. Based on an integrated analysis of the regional surface geology, tectonic setting, and depositional environment, and within the constraints of gravity to ft with electrical structure, a tectonic framework of two subsags sandwiched by an uplift is proposed for the Tuolai Sag. The scale of the northern subsag is large, with development of pre-Carboniferous nappe as well as of Carboniferous–Permian strata within the lower part of the nappe. The southern subsag is small and flled mainly with Carboniferous–Permian strata.

2

A Late Carboniferous olistostrome at the front of the Southern Tian Shan nappes (Kadamzhai and Khaidarkan deposits, Kyrgyzstan)

Hnylko Oleh, Tsukornyk Ihor, Heneralova Larysa, Dvorzhak Oleksiy

Geological Quarterly

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2019

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Vol. 63, No. 2

407--423

EN

A Late Carboniferous (Early Moscovian) olistostrome developed in the Kadamzhai and Khaidarkan gold-antimony-mercury deposits on the Alay Ridge northern slope (Kyrgyzstan), at the front of the Late Paleozoic Southern Tian Shan nappes, is characterized. It comprises a sub-nappe olistostrome in a collisional tectonic setting. The olistostrome contains olistoliths and olistoplaques containing parts of the mid-Paleozoic sedimentary successions belonging to the parautochthon and lower nappes of the northern Bukantau-Kokshaal branch of the Southern Tian Shan nappe belt. The olistostrome accumulated ahead the advancing nappes in the foredeep basin that was filled with turbidities and debris-flow deposits (Tolubai Formathion). The parautochthon was partly dismembered into thrust limestone sheets which disintegrated and slid into unconsolidated sediments of the foredeep basin, forming large limestone olistoliths and olistoplaques. Olistoliths containing shales and bedded cherts were slid from the lower nappes. Tectonic breccias up to melange scale are present in some olistoliths, suggesting tectonic disintegration within the nappe pile and the subsequent sliding of the tectonized blocks into the olistostrome basin. Ore-bearing silicified rocks (so-called “jasperoids”) with antimony-mercury and gold mineralization are located predominantly along the contacts of the limestone olistoliths/olistoplaques with a terrigenous matrix.

3

Sharp-crested weir head losses investigation

Korniichuk V., Khlapuk M., Bezusyak O., Yasinska L.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2018

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z. 65, nr 1

27--34

EN

The work is devoted to the rectangular sharp-crested weir calculation methods improvement. This can be realized by using mathematical model developed on energy and momentum conservation principles. In order to get energy conservation equation within sharp-crested weir we have to know weir head losses. This article presents theoretical and experimental investigations of the sharp-crested weir head losses. The height of the weir plate pw and weir head H are estimated as main operating factors that determine hydraulic weir outbound parameters: threshold depth h and the specific weir flow q. The flow moving over sharp-crested weir suffers sudden vertical contraction and transforms from the uniform flow to a jet. Mentioned above, causes sharp-crested weir head losses. To determine these losses, we propose to use Hind’s formula that describes similar contraction losses in the channel. Experimental investigations proved Hind’s formula application adequacy to evaluate these losses. Sharpcrested weir energy conservation equation that includes head losses is determined. Graphs set out in the article disclose the influence of the main operating factors and their ratio on the relative head losses.

4

Olistostromes in the Miocene salt-bearing folded deposits at the front of the Ukrainian Carpathian orogen

Hnylko O.

Geological Quarterly

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2014

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Vol. 58, No. 3

381--392

EN

The origin of the olistostromes at the front of the Ukrainian Carpathian orogen is related to Miocene synsedimentary thrust movements of the Carpathian accretionary prism and to erosion of uplifted areas of the Boryslav-Pokuttya Nappe in the front of the accretionary prism. There are two olistostrome complexes. The first is the Lower Miocene Polyanytsya-Vorotyshcha Olistostrome with clasts of molasse and flysch deposits formed in a piggy-back basin on the inner part of the Boryslav-Pokuttya Nappe at the top of the accretionary wedge. This olistostrome is associated with the Sloboda Conglomerate derived from the fore-bulge at the foreland of the Boryslav-Pokuttya Nappe. The second one is the Middle Miocene Lanchyn Olistostrome with olistoliths of strongly deformed molasse deposits. These olistoliths were slid from the uplifted front of the Boryslav-Pokuttya Nappe. The Lanchyn Olistostrome was deposited at front of this nappe in a foredeep basin.

5

The Tatras - nappes and landscapes

Felisiak I.

Geoturystyka

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2008

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nr 2

75-87

EN

Geological structure of the Tatra Mts is a result of long-lasting processes. The key nappes have already been completed some 65 Ma ago. However as a mountain range the Tatras has emerged at the surface only 5 Ma ago, when a piece of continental crust separated from African continent at the beginning of Mesozoic era ultimately collided with Europe. Thus, the crystalline core of the Tatras, which builts also the highest crest is a fragment of Africa. This monumental mountains are, however, not an effect of the overthrusting but they resulted from young, vertical tectonic movements, which are still active and which sometimes shake the whole Podhale region. The following paper explains how the Tatras were formed. The figures enclosed illustrate the succeeding formation stages of the mountain range and the photographs allow the Reader to compare drawings with the field. Welcome to the Tatras.

PL

Struktura geologiczna Tatr formowała się bardzo długo, a kluczowe dla niej płaszczowiny były już gotowe przed 65 milionami lat. Pomimo tego jako góry Tatry zaczęły się wyraźnie zaznaczać na powierzchni dopiero 5 mln lat temu. Trzeba było aby kawał skorupy kontynentalnej, oderwany od Afryki z początkiem ery Mezozoicznej, ostatecznie wbił się w kontynent Europejski. Jego fragmentem, okruchem Afryki, jest trzon krystaliczny tworzący m. in. Tatry Wysokie. Ich imponujący wygląd nie jest wszakże efektem ruchów nasuwczych a młodych przesunięć pionowych, które do dziś czasami trzęsą Podhalem. Jak to się stało opisuje poniższy artykuł. Zamieszczone w nim rysunki ilustrują kolejne stadia rozwoju Tatr. Liczne zdjęcia pozwalają porównać papierowe konstrukcje z rzeczywistymi dziełami natury. Zapraszam do lektury i wycieczki w Tatry. Autor.

6

Geodynamic evolution of the Tatra Mts. and the Pieniny Klippen Belt (Western Carpathians) : problems and comments

Jurewicz E.

Acta Geologica Polonica

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2005

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Vol. 55, no. 3

295-338

EN

The geodynamic evolution of the Pieniny Klippen Belt (PKB) and the Tatra Mts. assumes that: The Oravic-Vahic Basin developed due to Jurassic rifting processes with thinned continental crust. The oblique rift without rift-related volcanism had probably a WSW-ENE course. Late Cretaceous thrust-folding of the Choč, Križna and High-Tatric nappes took place underwater and at considerable overburden pressure (ok. ~6-7 km). The geometry of the structures was strongly disturbed by pressure solution processes leading to considerable mass loss. Nappe-folding in the PKB was connected with the slow and flat subduction of thinned continental crust of the Vahicum-Oravicum under the northern margin of the Central Carpathians Block.In the Tatra Mts. and the PKB, the nappe thrust-folding was influenced by a strike-slip shear zone between the edge of the Central Carpathians and the PKB and caused e.g. the counter-clockwise rotation of the Tatra block and relative changing directions of thrusting. The consequence of Miocene oblique subduction and subsequent collision of the North-European continental crust with the Central Carpathian Block was the activation of NNW-SSE deep fault zones. With one of these - the Dunajec Fault - were connected en echelon shears trading on the andesite dykes swarm. Miocene collision caused the disintegration of the Central Carpathian Block into individual massifs and their rotational uplift. The value of rotation around the horizontal axis for the Tatra Massif is estimated at ~40°.