Pub Date : 2020-08-01DOI: 10.31577/geolcarp.71.4.6
L. Krmíček, Martin J. TIMMERMAN, Martin A. ZIEMANN, M. Sudo, J. Ulrych
40Ar/39Ar step-heating of mica and amphibole megacrysts from hauyne-bearing olivine melilitite scoria/tephra from the Železná hůrka yielded a 435±108 ka isotope correlation age for phlogopite and a more imprecise 1.55 Ma total gas age of the kaersutite megacryst. The amphibole megacrysts may constitute the first, and the younger phlogopite megacrysts the later phase of mafic, hydrous melilitic magma crystallization. It cannot be ruled out that the amphibole megacrysts are petrogenetically unrelated to tephra and phlogopite megacrysts and were derived from mantle xenoliths or disaggregated older, deep crustal pegmatites. This is in line both with the rarity of amphibole at Železná hůrka and with the observed signs of magmatic resorption at the edges of amphibole crystals.
{"title":"40Ar/39Ar step-heating dating of phlogopite and kaersutite megacrysts from the Železná hůrka (Eisenbühl) Pleistocene scoria cone, Czech Republic","authors":"L. Krmíček, Martin J. TIMMERMAN, Martin A. ZIEMANN, M. Sudo, J. Ulrych","doi":"10.31577/geolcarp.71.4.6","DOIUrl":"https://doi.org/10.31577/geolcarp.71.4.6","url":null,"abstract":"40Ar/39Ar step-heating of mica and amphibole megacrysts from hauyne-bearing olivine melilitite scoria/tephra from the Železná hůrka yielded a 435±108 ka isotope correlation age for phlogopite and a more imprecise 1.55 Ma total gas age of the kaersutite megacryst. The amphibole megacrysts may constitute the first, and the younger phlogopite megacrysts the later phase of mafic, hydrous melilitic magma crystallization. It cannot be ruled out that the amphibole megacrysts are petrogenetically unrelated to tephra and phlogopite megacrysts and were derived from mantle xenoliths or disaggregated older, deep crustal pegmatites. This is in line both with the rarity of amphibole at Železná hůrka and with the observed signs of magmatic resorption at the edges of amphibole crystals.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43987600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-01DOI: 10.31577/geolcarp.71.4.3
Éva Oravecz, Szilvia Kövér, G. Héja, L. Fodor
Detailed fieldwork was carried out in the SW Bükk Mts. at six locations in order to understand the Jurassic pre-orogenic deformation. All localities expose Middle Jurassic oolitic limestones with grains probably derived from the Adriatic Carbonate Platform and therefore from the Dinaridic passive margin of the Neotethys Ocean. Results of the structural analysis revealed early, soft-sedimentary deformation structures. The observed small-scale normal faults are characterized by rounded, curved shapes without any discrete fault planes (sealed faults) and the displaced beds often thicken towards the faults. These faults were interpreted as syn-sedimentary/syn-diagenetic faults, meaning that the deformation took place in unconsolidated or semi-consolidated sediments. During the early diagenetic silica mobilization, the already-present early faults may have served as conduits of silica-rich fluids, which led to the formation of planar silica injection dykes. Sedimentary slump folds were also identified based on the presence of underlying detachment slip surfaces and the observed thickness changes and onlap surfaces within the folded layers. The significance of these early normal faults and slump folds is that they are the first direct evidence for pre-orogenic deformation in the Bükk Mts. The overall structural data suggest NE–SW or NNE–SSW striking early faults and SE to S verging slump folds in the present-day coordinates. By reconstructing the Cenozoic rotations of the Bükk Mts. this means a roughly NW–SE striking original margin and a south-westward facing paleoslope for the Middle Jurassic. Considering the paleogeographic setting of the Adriatic Platform, this paleoslope direction is possible if the deposition area was located above a deeply submerged tilted normal fault block or alternatively, along the landward side of a larger intraoceanic high. The extensional structures may indicate that the Bükk Mts. were closer to the passive margin than the already ongoing intra-oceanic subduction and related trench, all governed by compression.
为了解侏罗系造山前变形，在西南段 kk山6个地点进行了详细的野外考察。所有地点均暴露出中侏罗世鲕粒灰岩，其颗粒可能来自亚得里亚海碳酸盐岩台地，因此可能来自新特提斯洋的Dinaridic被动边缘。构造分析结果揭示了早期的软沉积变形构造。观测到的小尺度正断层以圆形、弯曲的形状为特征，没有任何离散的断层面(封闭断层)，位移层往往向断层方向加厚。这些断裂被解释为同沉积/同成岩断裂，这意味着变形发生在未固结或半固结的沉积物中。早成岩过程中，已存在的早断层可能成为富硅流体的输送通道，形成平面型注硅岩脉。根据下伏滑脱滑面的存在以及观察到的褶皱层厚度变化和上覆面，确定了沉积滑塌褶皱。这些早期正断层和滑塌褶皱的意义在于，它们是 kk山系造山前变形的第一个直接证据。总体构造资料表明，在现今的座标上，北东-西向或北北-南南向的早期断裂和东南-南向的滑塌褶皱。通过重建 kk山脉新生代的旋转，表明中侏罗世的原始边缘大致为西北-东南走向，古斜坡面向西南。考虑到亚得里亚海地台的古地理背景，如果沉积区位于一个深埋的倾斜正断块之上，或者沿着一个较大的洋内高压的向陆侧，则可能存在这个古斜坡方向。伸展构造可能表明，与已经在进行的洋内俯冲和相关海沟相比，b kk mms更接近被动边缘，所有这些都受挤压控制。
{"title":"Syn-sedimentary and early deformation structures as indications for Jurassic pre-orogenic deformation in the SW Bükk Mts.","authors":"Éva Oravecz, Szilvia Kövér, G. Héja, L. Fodor","doi":"10.31577/geolcarp.71.4.3","DOIUrl":"https://doi.org/10.31577/geolcarp.71.4.3","url":null,"abstract":"Detailed fieldwork was carried out in the SW Bükk Mts. at six locations in order to understand the Jurassic pre-orogenic deformation. All localities expose Middle Jurassic oolitic limestones with grains probably derived from the Adriatic Carbonate Platform and therefore from the Dinaridic passive margin of the Neotethys Ocean. Results of the structural analysis revealed early, soft-sedimentary deformation structures. The observed small-scale normal faults are characterized by rounded, curved shapes without any discrete fault planes (sealed faults) and the displaced beds often thicken towards the faults. These faults were interpreted as syn-sedimentary/syn-diagenetic faults, meaning that the deformation took place in unconsolidated or semi-consolidated sediments. During the early diagenetic silica mobilization, the already-present early faults may have served as conduits of silica-rich fluids, which led to the formation of planar silica injection dykes. Sedimentary slump folds were also identified based on the presence of underlying detachment slip surfaces and the observed thickness changes and onlap surfaces within the folded layers. The significance of these early normal faults and slump folds is that they are the first direct evidence for pre-orogenic deformation in the Bükk Mts. The overall structural data suggest NE–SW or NNE–SSW striking early faults and SE to S verging slump folds in the present-day coordinates. By reconstructing the Cenozoic rotations of the Bükk Mts. this means a roughly NW–SE striking original margin and a south-westward facing paleoslope for the Middle Jurassic. Considering the paleogeographic setting of the Adriatic Platform, this paleoslope direction is possible if the deposition area was located above a deeply submerged tilted normal fault block or alternatively, along the landward side of a larger intraoceanic high. The extensional structures may indicate that the Bükk Mts. were closer to the passive margin than the already ongoing intra-oceanic subduction and related trench, all governed by compression.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45718624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-01DOI: 10.31577/geolcarp.71.4.4
Kamil Kropáč, Z. Dolníček, P. Uher, D. Buriánek, Amina Safai, Tomáš Urubek
Sills of hydrothermally altered alkaline magmatic rock (teschenite) of Lower Cretaceous age at the Čerťák and Řepiště sites in the Silesian Unit (Flysch Belt of the Outer Western Carpathians, Czech Republic) host leucocratic dykes and nests which contain accessory minerals enriched in Zr, Nb and REE: Zr-, Nb-rich titanite, zircon, gittinsite, pyrochlore, monazite, REE-rich apatite, epidote, and vesuvianite. Titanite forms wedge-shaped crystals or irregular aggregates enclosed in the analcime groundmass or overgrowths on Zr-rich ferropargasite and taramite or Zr-rich aegirine–augite to aegirine. Titanite crystals show oscillatory or irregular patchy to sector zoning and contain up to 17.7 wt. % ZrO2 and 19.6 wt. % Nb2O5, and ≤1.1 wt. % REE2O3. High-field-strength elements (HFSE) are incorporated into the structure of the studied titanite predominantly by substitutions: (i) [6]Ti4+ ↔ [6]Zr4+; (ii) [6]Ti4+ + [6]Al3+ ↔ [6]Zr4+ + [6]Fe3+; and (iii) [6]2Ti4+ ↔ [6]Nb5+ + [6](Al, Fe)3+. Magmatic fractional crystallization, high-temperature hydrothermal autometasomatic overprint and low-temperature hydrothermal alterations resulted in the formation of the HFSE-rich mineral assemblages within the leucocratic teschenites. Autometamorphic processes caused by high-temperature hypersaline aqueous solutions (salinity ~50 wt. %, ~390–510 °C), which were released from the HFSE-enriched residual melt, played a major role in the crystallization of Zr-, Nb-, and REE-rich minerals. The mobilization of HFSE could have occurred either by their sequestration into a fluid phase exsolved from the crystallizing melt or by superimposed alteration processes. The distinctive positive Eu anomaly (EuCN/Eu* = 1.85) of leucocratic dykes infers possible mixing of Eu2+-bearing magmatic fluids with more oxidized fluids.
{"title":"Zirconian–niobian titanite and associated Zr-, Nb-, REE-rich accessory minerals: Products of hydrothermal overprint of leucocratic teschenites (Silesian Unit, Outer Western Carpathians, Czech Republic)","authors":"Kamil Kropáč, Z. Dolníček, P. Uher, D. Buriánek, Amina Safai, Tomáš Urubek","doi":"10.31577/geolcarp.71.4.4","DOIUrl":"https://doi.org/10.31577/geolcarp.71.4.4","url":null,"abstract":"Sills of hydrothermally altered alkaline magmatic rock (teschenite) of Lower Cretaceous age at the Čerťák and Řepiště sites in the Silesian Unit (Flysch Belt of the Outer Western Carpathians, Czech Republic) host leucocratic dykes and nests which contain accessory minerals enriched in Zr, Nb and REE: Zr-, Nb-rich titanite, zircon, gittinsite, pyrochlore, monazite, REE-rich apatite, epidote, and vesuvianite. Titanite forms wedge-shaped crystals or irregular aggregates enclosed in the analcime groundmass or overgrowths on Zr-rich ferropargasite and taramite or Zr-rich aegirine–augite to aegirine. Titanite crystals show oscillatory or irregular patchy to sector zoning and contain up to 17.7 wt. % ZrO2 and 19.6 wt. % Nb2O5, and ≤1.1 wt. % REE2O3. High-field-strength elements (HFSE) are incorporated into the structure of the studied titanite predominantly by substitutions: (i) [6]Ti4+ ↔ [6]Zr4+; (ii) [6]Ti4+ + [6]Al3+ ↔ [6]Zr4+ + [6]Fe3+; and (iii) [6]2Ti4+ ↔ [6]Nb5+ + [6](Al, Fe)3+. Magmatic fractional crystallization, high-temperature hydrothermal autometasomatic overprint and low-temperature hydrothermal alterations resulted in the formation of the HFSE-rich mineral assemblages within the leucocratic teschenites. Autometamorphic processes caused by high-temperature hypersaline aqueous solutions (salinity ~50 wt. %, ~390–510 °C), which were released from the HFSE-enriched residual melt, played a major role in the crystallization of Zr-, Nb-, and REE-rich minerals. The mobilization of HFSE could have occurred either by their sequestration into a fluid phase exsolved from the crystallizing melt or by superimposed alteration processes. The distinctive positive Eu anomaly (EuCN/Eu* = 1.85) of leucocratic dykes infers possible mixing of Eu2+-bearing magmatic fluids with more oxidized fluids.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48636363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-01DOI: 10.31577/geolcarp.71.4.5
D. Balen, P. Schneider, H. Massonne, J. Opitz, J. Luptáková, M. Putiš, Zorica Petrinec
An alkali-feldspar granite (Požega granite) of reddish colour occurs in northern Croatia in the Cretaceous suture zone (Sava Zone) between the collided plates of Europe and Adria (Africa). This granite is mainly composed of alkali feldspar (perthite) and quartz, with small amounts of albite. Accessories are hematite with ilmenite exsolution, zircon, apatite and monazite. Anatase, rutile (?), kokchetavite, and kumdykolite are found only as inclusions in zircon. The granite shows a geochemical signature typical for an A2-subtype granite, characterized by a peraluminous, highly siliceous and alkaline composition, and belongs to the group of oxidized and ferroan granites with low CaO, MgO, and MnO contents and high FeOT / FeOT + MgO ratios. Trace element contents plotted in chondrite and primitive mantle normalized element diagrams show positive anomalies of K, Pb, and Zr and negative anomalies of Ba, Nb, P, Eu, and Ti. Based on whole-rock geochemical data, the magma originated mainly from melting of lower continental crust. According to the zircon typology (D and J5 types prevail), zircon and whole-rock chemistry, and high Zr-saturation temperatures (T=860–950 °C), the melting process at high temperature and dry conditions could have been triggered by upwelling hot mantle. The ascent of the thus produced A-type granitic magma into the Europe–Adria suture was fast. The Požega granite indicates the transition from compression to extension accompanied by opening of a sedimentary basin. According to the 206Pb/238U versus 207Pb/235U concordia age determined on zircon, this event occurred 83.6±1.5 Ma ago.
{"title":"The Late Cretaceous A-type alkali-feldspar granite from Mt. Požeška Gora (N Croatia): Potential marker of fast magma ascent in the Europe–Adria suture zone","authors":"D. Balen, P. Schneider, H. Massonne, J. Opitz, J. Luptáková, M. Putiš, Zorica Petrinec","doi":"10.31577/geolcarp.71.4.5","DOIUrl":"https://doi.org/10.31577/geolcarp.71.4.5","url":null,"abstract":"An alkali-feldspar granite (Požega granite) of reddish colour occurs in northern Croatia in the Cretaceous suture zone (Sava Zone) between the collided plates of Europe and Adria (Africa). This granite is mainly composed of alkali feldspar (perthite) and quartz, with small amounts of albite. Accessories are hematite with ilmenite exsolution, zircon, apatite and monazite. Anatase, rutile (?), kokchetavite, and kumdykolite are found only as inclusions in zircon. The granite shows a geochemical signature typical for an A2-subtype granite, characterized by a peraluminous, highly siliceous and alkaline composition, and belongs to the group of oxidized and ferroan granites with low CaO, MgO, and MnO contents and high FeOT / FeOT + MgO ratios. Trace element contents plotted in chondrite and primitive mantle normalized element diagrams show positive anomalies of K, Pb, and Zr and negative anomalies of Ba, Nb, P, Eu, and Ti. Based on whole-rock geochemical data, the magma originated mainly from melting of lower continental crust. According to the zircon typology (D and J5 types prevail), zircon and whole-rock chemistry, and high Zr-saturation temperatures (T=860–950 °C), the melting process at high temperature and dry conditions could have been triggered by upwelling hot mantle. The ascent of the thus produced A-type granitic magma into the Europe–Adria suture was fast. The Požega granite indicates the transition from compression to extension accompanied by opening of a sedimentary basin. According to the 206Pb/238U versus 207Pb/235U concordia age determined on zircon, this event occurred 83.6±1.5 Ma ago.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":"71 1","pages":"361-381"},"PeriodicalIF":1.3,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47446432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.31577/geolcarp.71.3.2
Milan Gargulák, D. Ozdín, P. Povinec, S. Strekopytov, A. Jull, I. Sýkora, V. Porubčan, S. Farsang
A single 13.95 kg mass of a slightly weathered iron meteorite was found in the forest near Smolenice (48°31.2’N, 17°23.9’E; Trnava County, Slovakia). The bulk chemical composition (in wt. %) is: Fe 88.78, Ni 8.16, Co 0.38, P 0.05, S<0.006 and (in μg/g): Ge<0.18, Ir 1.67, Ga 1.80, Cr 87.3, Cu 135.1, As 4.52, Mo 5.82, Sn 1.53, W 0.56, Re 0.18, Ru 3.56, Rh 0.90, Pd 4.12, Pt 5.35, Au 1.19, Zn<5, B<0.68, Pb<0.06. Bulk geochemistry, and Ni, Ga, Ge and Ir contents in particular suggest that the meteorite is an octahedrite belonging to the IVA group. The average thickness of kamacite lamellae is 0.22 mm, ranking it as fine octahedrite (Of). The mineral composition is simple, the most abundant minerals being iron (kamacite) (5.16–7.36 wt. % Ni) followed by taenite (16.73–33.93 wt. % Ni). Troilite nodules and daubréelite inclusions and thin veinlets are rare. The Widmanstätten pattern is uniform across the meteorite and plessite structure is developed locally. Analyses of cosmogenic radionuclides (14C and 26Al) indicate that the radius of the Smolenice meteorite could be 30±10 cm and its terrestrial age 11±2 kyr.
{"title":"Mineralogy, geochemistry and classification of the new Smolenice iron meteorite from Slovakia","authors":"Milan Gargulák, D. Ozdín, P. Povinec, S. Strekopytov, A. Jull, I. Sýkora, V. Porubčan, S. Farsang","doi":"10.31577/geolcarp.71.3.2","DOIUrl":"https://doi.org/10.31577/geolcarp.71.3.2","url":null,"abstract":"A single 13.95 kg mass of a slightly weathered iron meteorite was found in the forest near Smolenice (48°31.2’N, 17°23.9’E; Trnava County, Slovakia). The bulk chemical composition (in wt. %) is: Fe 88.78, Ni 8.16, Co 0.38, P 0.05, S<0.006 and (in μg/g): Ge<0.18, Ir 1.67, Ga 1.80, Cr 87.3, Cu 135.1, As 4.52, Mo 5.82, Sn 1.53, W 0.56, Re 0.18, Ru 3.56, Rh 0.90, Pd 4.12, Pt 5.35, Au 1.19, Zn<5, B<0.68, Pb<0.06. Bulk geochemistry, and Ni, Ga, Ge and Ir contents in particular suggest that the meteorite is an octahedrite belonging to the IVA group. The average thickness of kamacite lamellae is 0.22 mm, ranking it as fine octahedrite (Of). The mineral composition is simple, the most abundant minerals being iron (kamacite) (5.16–7.36 wt. % Ni) followed by taenite (16.73–33.93 wt. % Ni). Troilite nodules and daubréelite inclusions and thin veinlets are rare. The Widmanstätten pattern is uniform across the meteorite and plessite structure is developed locally. Analyses of cosmogenic radionuclides (14C and 26Al) indicate that the radius of the Smolenice meteorite could be 30±10 cm and its terrestrial age 11±2 kyr.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":"71 1","pages":"221-232"},"PeriodicalIF":1.3,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47396845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.31577/geolcarp.71.3.1
M. Janák, Š. Méres, L. Medaris, Jr.
Metaultramafic rocks closely associated with eclogites in the Veporic unit of the Western Carpathians record a complex P–T evolution, including the effects of high-pressure (HP) metamorphism. The investigated metaultramafite is chemically similar to pyroxenite, has a fineto medium-grained texture, is composed predominantly of olivine and amphibole, and contains minor amounts of garnet, orthopyroxene, spinel, chlorite, ilmenite and carbonates. The highpressure mineral assemblage is garnet (XMg = 0.46–0.47) + olivine (XMg = 0.71–0.73) + low-Al orthopyroxene (XMg = 0.77–0.78; Al = 0.02–0.03 apfu) + ilmenite + chlorite (XMg = 0.87–0.89) + Cr-spinel. Chromium-rich spinel is most likely a relict from the pre-HP metamorphic stage, possibly of magmatic origin. Calculations using a garnet– orthopyroxene Fe–Mg exchange thermometer, Al-in-orthopyroxene barometer, and thermodynamic modelling in the system SiO2–TiO2– Al2O3–FeO–MgO–CaO–H2O indicate that the peak conditions of metamorphism reached 2.4±0.4 GPa and 702±20 °C. Subsequent decompression and retrogression is recorded by the formation of aluminous orthopyroxene, replacement of garnet by symplectites of Al-spinel and amphibole (hornblende), transformation of Cr-spinel to Al-spinel and formation of abundant amphibole in the matrix. Metaultramafic rocks in the Veporic unit thus provide evidence, in addition to that from associated eclogites, for high-pressure metamorphism in the pre-Alpine basement of the Western Carpathians, which is most likely of Variscan age.
{"title":"Eclogite facies metaultramafite from the Veporic Unit (Western Carpathians, Slovakia)","authors":"M. Janák, Š. Méres, L. Medaris, Jr.","doi":"10.31577/geolcarp.71.3.1","DOIUrl":"https://doi.org/10.31577/geolcarp.71.3.1","url":null,"abstract":"Metaultramafic rocks closely associated with eclogites in the Veporic unit of the Western Carpathians record a complex P–T evolution, including the effects of high-pressure (HP) metamorphism. The investigated metaultramafite is chemically similar to pyroxenite, has a fineto medium-grained texture, is composed predominantly of olivine and amphibole, and contains minor amounts of garnet, orthopyroxene, spinel, chlorite, ilmenite and carbonates. The highpressure mineral assemblage is garnet (XMg = 0.46–0.47) + olivine (XMg = 0.71–0.73) + low-Al orthopyroxene (XMg = 0.77–0.78; Al = 0.02–0.03 apfu) + ilmenite + chlorite (XMg = 0.87–0.89) + Cr-spinel. Chromium-rich spinel is most likely a relict from the pre-HP metamorphic stage, possibly of magmatic origin. Calculations using a garnet– orthopyroxene Fe–Mg exchange thermometer, Al-in-orthopyroxene barometer, and thermodynamic modelling in the system SiO2–TiO2– Al2O3–FeO–MgO–CaO–H2O indicate that the peak conditions of metamorphism reached 2.4±0.4 GPa and 702±20 °C. Subsequent decompression and retrogression is recorded by the formation of aluminous orthopyroxene, replacement of garnet by symplectites of Al-spinel and amphibole (hornblende), transformation of Cr-spinel to Al-spinel and formation of abundant amphibole in the matrix. Metaultramafic rocks in the Veporic unit thus provide evidence, in addition to that from associated eclogites, for high-pressure metamorphism in the pre-Alpine basement of the Western Carpathians, which is most likely of Variscan age.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":"71 1","pages":"209-220"},"PeriodicalIF":1.3,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48998549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.31577/geolcarp.71.3.3
M. Slobodník, P. Gadas, D. Všianský, A. Přichystal, Z. Losos
The crystalline rocks of the Silesicum unit of the Bohemian Massif host two principal types of hydrothermal quartz veins. Veins associated with granitoids are primarily quartz with wollastonite and epidote and accompanied by hydrothermal alteration of host rocks whereas others are of the more complex “Alpine-type”. L + V + S (liquid + vapour + solid phase) fluid inclusions within quartz crystals contain muscovite and ± calcite (± haematite) as solid phases and homogenisation temperatures are between 124 and 176 °C. Trapped fluids are uniformly of the H2O–NaCl–CaCl2 ± MgCl2 ± KCl system with a salinity between 9.1 and 26.8 mass % (NaCl + CaCl2). The variable Na/Ca ratios result from different intensity of fluid-rock reactions. The ubiquitous muscovite is a product of fluid-rock interactions. Oxygen isotope evidence indicates that the fluids were a mixture of meteoric and marine waters in deep regional-scale convection systems. The studied type of fluids represents a post-Variscan hydrothermal system and shows the extent of migration pathways in the upper crust on the north-eastern edge of the Bohemian Massif.
波西米亚地块西里西亚单元的结晶岩中含有两种主要类型的热液石英脉。与花岗岩体伴生的矿脉主要为石英、硅灰石和绿帘石，伴寄主岩热液蚀变，也有较为复杂的“高山型”矿脉。石英晶体内的L + V + S(液体+蒸汽+固相)流体包裹体含有白云母和±方解石(±赤铁矿)作为固相，均质温度在124至176℃之间。捕获流体均为H2O-NaCl-CaCl2±MgCl2±KCl体系，矿化度在9.1 ~ 26.8质量% (NaCl + CaCl2)之间。不同的Na/Ca比值是由不同强度的流体-岩石反应引起的。无处不在的白云母是流体-岩石相互作用的产物。氧同位素证据表明，这些流体是深层区域尺度对流系统中大气和海水的混合物。所研究的流体类型代表了后瓦里斯坎热液系统，并显示了波希米亚地块东北边缘上地壳的迁移路径程度。
{"title":"Regional low-temperature fluid flow indicated by quartz mineralization in Silesicum, NE Bohemian massif","authors":"M. Slobodník, P. Gadas, D. Všianský, A. Přichystal, Z. Losos","doi":"10.31577/geolcarp.71.3.3","DOIUrl":"https://doi.org/10.31577/geolcarp.71.3.3","url":null,"abstract":"The crystalline rocks of the Silesicum unit of the Bohemian Massif host two principal types of hydrothermal quartz veins. Veins associated with granitoids are primarily quartz with wollastonite and epidote and accompanied by hydrothermal alteration of host rocks whereas others are of the more complex “Alpine-type”. L + V + S (liquid + vapour + solid phase) fluid inclusions within quartz crystals contain muscovite and ± calcite (± haematite) as solid phases and homogenisation temperatures are between 124 and 176 °C. Trapped fluids are uniformly of the H2O–NaCl–CaCl2 ± MgCl2 ± KCl system with a salinity between 9.1 and 26.8 mass % (NaCl + CaCl2). The variable Na/Ca ratios result from different intensity of fluid-rock reactions. The ubiquitous muscovite is a product of fluid-rock interactions. Oxygen isotope evidence indicates that the fluids were a mixture of meteoric and marine waters in deep regional-scale convection systems. The studied type of fluids represents a post-Variscan hydrothermal system and shows the extent of migration pathways in the upper crust on the north-eastern edge of the Bohemian Massif.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":"71 1","pages":"223-248"},"PeriodicalIF":1.3,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44261904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.31577/geolcarp.71.3.5
Attila Attila Ősi, M. Szabó, Gábor Botfalvai
Tanystropheus and other possible archosauromorph fossils have been discovered from Middle to Upper Triassic shallow marine sedimentary sections in Villány (Villány Hills, southern Hungary). Four fragmentary cervical vertebrae can be assigned to Tanystropheus sp. based on characteristic features including the strongly elongate and hollow vertebral body with extremely reduced neural spine. Besides the cervicals, various teeth, classified into four different morphotypes including longitudinally striated, carinated and ziphodont ones, are thought to belong to archosauromorphs, since they markedly differ from the frequently found teeth of fish and sauropterygians. In addition, three enigmatic cranial bones that might represent some circumorbital elements, have been found as well, and are referred to here as Sauropsida indet. These fossils, originated from the same tectonic unit as those from the Anisian of Bihor (Romania), are of great importance for a better understanding of the poorly known semi-aquatic to terrestrial vertebrate fauna of the Middle to Late Triassic of central Europe.
{"title":"Tanystropheus and other archosauromorph reptile remains from the Middle and Late Triassic of Villány (Villány Hills, Hungary)","authors":"Attila Attila Ősi, M. Szabó, Gábor Botfalvai","doi":"10.31577/geolcarp.71.3.5","DOIUrl":"https://doi.org/10.31577/geolcarp.71.3.5","url":null,"abstract":"Tanystropheus and other possible archosauromorph fossils have been discovered from Middle to Upper Triassic shallow marine sedimentary sections in Villány (Villány Hills, southern Hungary). Four fragmentary cervical vertebrae can be assigned to Tanystropheus sp. based on characteristic features including the strongly elongate and hollow vertebral body with extremely reduced neural spine. Besides the cervicals, various teeth, classified into four different morphotypes including longitudinally striated, carinated and ziphodont ones, are thought to belong to archosauromorphs, since they markedly differ from the frequently found teeth of fish and sauropterygians. In addition, three enigmatic cranial bones that might represent some circumorbital elements, have been found as well, and are referred to here as Sauropsida indet. These fossils, originated from the same tectonic unit as those from the Anisian of Bihor (Romania), are of great importance for a better understanding of the poorly known semi-aquatic to terrestrial vertebrate fauna of the Middle to Late Triassic of central Europe.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":"71 1","pages":"264-273"},"PeriodicalIF":1.3,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43885519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.31577/geolcarp.71.3.4
I. Gamkrelidze, D. Shengelia, G. Chichinadze, Yuan-Hsi Lee, A. Okrostsvaridze, G. Beridze, Kristina Vardanashvili
Here we report U–Pb zircon age data, obtained using LA–ICP–MS, from a total of 14 rocks of the Pass and Elbrus sub-zones of the Main Range Zone of the Greater Caucasus, which differ quite significantly from each other in composition of sedimentary and igneous rocks. Both exotic (detrital) zircons, and those formed within the Greater Caucasus are revealed. The ages of detrital zircons range from 2981 to 668 Ma. On the basis of weighted mean age data among in situ zircons from meta-sedimentary rocks in both sub-zones figures of 626± 2 Ma and 627± 19 Ma were detected, which corresponds to the earliest – Cadomian stage of high temperature regional metamorphism. From meta-sedimentary rocks of the Elbrus sub-zone figures – 461±5.3 Ma, 457±12 Ma indicate manifestation of the Ordovician (tectonically associated with Caledonian orogeny) stage of high temperature prograde regional metamorphism. Figures from granitoid rocks of both sub-zones – 454±9 Ma, 468±5 Ma and 471.7±4.6 Ma were obtained, which also correspond to the Caledonian stage of synmetamorphic granitoid formation. Besides, figures from the meta-sedimentary rocks of the Pass sub-zone – 312.5±4 Ma, 317.0±8.3 Ma correspond to Late Variscan regressive regional metamorphism. In addition, figures obtained from the granitoid rocks of both sub-zones – 309±8 Ma, 310.9 Ma, 325±4 Ma, 311±5.9 Ma and 357±5.9 Ma correspond to the Late Variscan stage of synmetamorphic granitoid formation. These results are in good agreement with geological and petrological data for the Greater Caucasus.
{"title":"U–Pb LA–ICP–MS dating of zoned zircons from the Greater Caucasus pre-Alpine crystalline basement: Evidence for Cadomian to Late Variscan evolution","authors":"I. Gamkrelidze, D. Shengelia, G. Chichinadze, Yuan-Hsi Lee, A. Okrostsvaridze, G. Beridze, Kristina Vardanashvili","doi":"10.31577/geolcarp.71.3.4","DOIUrl":"https://doi.org/10.31577/geolcarp.71.3.4","url":null,"abstract":"Here we report U–Pb zircon age data, obtained using LA–ICP–MS, from a total of 14 rocks of the Pass and Elbrus sub-zones of the Main Range Zone of the Greater Caucasus, which differ quite significantly from each other in composition of sedimentary and igneous rocks. Both exotic (detrital) zircons, and those formed within the Greater Caucasus are revealed. The ages of detrital zircons range from 2981 to 668 Ma. On the basis of weighted mean age data among in situ zircons from meta-sedimentary rocks in both sub-zones figures of 626± 2 Ma and 627± 19 Ma were detected, which corresponds to the earliest – Cadomian stage of high temperature regional metamorphism. From meta-sedimentary rocks of the Elbrus sub-zone figures – 461±5.3 Ma, 457±12 Ma indicate manifestation of the Ordovician (tectonically associated with Caledonian orogeny) stage of high temperature prograde regional metamorphism. Figures from granitoid rocks of both sub-zones – 454±9 Ma, 468±5 Ma and 471.7±4.6 Ma were obtained, which also correspond to the Caledonian stage of synmetamorphic granitoid formation. Besides, figures from the meta-sedimentary rocks of the Pass sub-zone – 312.5±4 Ma, 317.0±8.3 Ma correspond to Late Variscan regressive regional metamorphism. In addition, figures obtained from the granitoid rocks of both sub-zones – 309±8 Ma, 310.9 Ma, 325±4 Ma, 311±5.9 Ma and 357±5.9 Ma correspond to the Late Variscan stage of synmetamorphic granitoid formation. These results are in good agreement with geological and petrological data for the Greater Caucasus.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":"1 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43659335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.31577/geolcarp.71.3.6
A. Vozárová, Katarína Šarinová, N. Rodionov, J. Vozár
U–Pb dating of magmatic zircons from the Permian basaltic metaandesites/metabasalts of the Tribeč Mts. yielded the Concordia ages of 263.1±2.6 Ma, which correspond to the Guadalupian Epoch in the time span of the uppermost Wordian/Capitanian Stages. These magmatic zircon ages clearly document the timing of the Mid-Permian lithospheric extension in the internal zone of the Variscan fragments in the Western Carpathians. The studied volcanic rocks with the associated metasediments belong to the Veporic Unit that overthrusts the Tatric Unit. The considered sequence was correlated with the Northern Veporic Permian rocks from the Čierťaž Mts. From the geochemical point of view, the studied volcanic rocks have a calc-alkaline magmatic trend with an affinity to continental within-plate tectonic setting, linked to the post-orogenic lithospheric extension. The detrital zircon population, obtained from the associated arkosic metagreywackes, displays mainly Tournaisian and Ediacaran zircon ages in the range of 342–367 and 546–631 Ma, respectively. Only a small number of Cambrian/Ordovician (499–466 Ma), Tonian (720–1000 Ma) and Paleoproterozoic/ Neoarchean (~1.9 Ga and ~2.5 Ga) zircon ages were determined. The similar association of zircon ages was found within the xenocrystic cores in the studied volcanic rocks. The presented detrital and xenocrystic zircon ages specify the provenance of the Tribeč Permian deposits from the Western Carpathian Crystalline Basement crust, characteristic of derivation from the Variscan magmatic rocks and reworked fragments of Cadomian crust.
{"title":"Zircon U–Pb geochronology from Permian rocks of the Tribeč Mts. (Western Carpathians, Slovakia)","authors":"A. Vozárová, Katarína Šarinová, N. Rodionov, J. Vozár","doi":"10.31577/geolcarp.71.3.6","DOIUrl":"https://doi.org/10.31577/geolcarp.71.3.6","url":null,"abstract":"U–Pb dating of magmatic zircons from the Permian basaltic metaandesites/metabasalts of the Tribeč Mts. yielded the Concordia ages of 263.1±2.6 Ma, which correspond to the Guadalupian Epoch in the time span of the uppermost Wordian/Capitanian Stages. These magmatic zircon ages clearly document the timing of the Mid-Permian lithospheric extension in the internal zone of the Variscan fragments in the Western Carpathians. The studied volcanic rocks with the associated metasediments belong to the Veporic Unit that overthrusts the Tatric Unit. The considered sequence was correlated with the Northern Veporic Permian rocks from the Čierťaž Mts. From the geochemical point of view, the studied volcanic rocks have a calc-alkaline magmatic trend with an affinity to continental within-plate tectonic setting, linked to the post-orogenic lithospheric extension. The detrital zircon population, obtained from the associated arkosic metagreywackes, displays mainly Tournaisian and Ediacaran zircon ages in the range of 342–367 and 546–631 Ma, respectively. Only a small number of Cambrian/Ordovician (499–466 Ma), Tonian (720–1000 Ma) and Paleoproterozoic/ Neoarchean (~1.9 Ga and ~2.5 Ga) zircon ages were determined. The similar association of zircon ages was found within the xenocrystic cores in the studied volcanic rocks. The presented detrital and xenocrystic zircon ages specify the provenance of the Tribeč Permian deposits from the Western Carpathian Crystalline Basement crust, characteristic of derivation from the Variscan magmatic rocks and reworked fragments of Cadomian crust.","PeriodicalId":12545,"journal":{"name":"Geologica Carpathica","volume":"71 1","pages":"274-287"},"PeriodicalIF":1.3,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43897148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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