The presented geological map at a scale of 1:75,000 shows a part of the Upper Mesozoic sedimentary belt exposed along the northern slopes of the Mongolian Altai in the Valley of Lakes (Western Mongolia). The Upper Jurassic to Lower Cretaceous formations of the Shiliin Nuruu Syncline, which have both lateral and vertical transitions, reach a total thickness of up to 1000 m. Poorly sorted conglomerates in the bottom of the sequence represent the proximal parts of the alluvial fans and grade up to the cycles of sandstones, mudstones, siltstones, marls, and coal seams of fluvial to lacustrine origin. Relics of terrestrial plants indicate a warm climate. The coalification corresponds to early brown coal. The rich Hauterivian-Aptian palaeontological association containing conchostracans, larvae of giant mayflies, gastropods, bivalves, and fish in the Anday Khudag and the Khulsan Gol formations could be compared with the Jehol Biota in northeast China.

The Mongolian Altai Domain of the Central Asian Orogenic Belt is formed by a giant Lower Palaeozoic accretionary wedge that was later thrust over the northerly Central Mongolian Microcontinent. This accretionary complex mainly consists of late Cambrian-Ordovician volcano-sedimentary rocks represented by various formations within the Tugrug Group which were deformed, metamorphosed and intruded by numerous plutons during the Devonian-Carboniferous orogenic events. In this work, we report new U-Pb zircon ages of two felsic igneous rocks indicating an existence of the so far neglected late Ordovician magmatic event affecting the Mongolian Altai accretionary wedge. The felsic volcanic sheet inside the upper part of the Tugrug Group in the western Gobi Altai Zone (eastern part of the Mongolian Altai Domain) yields an age of 457 +/- 2 Ma and nearby granite pluton intruding the entire volcano-sedimentary sequence gives an age of 445 +/- 1 Ma. Both rocks are high-K calc-alkaline, peraluminous, with similar geochemical patterns characterised by enrichment in mobile lithophile elements over Nb, Ti, P and Sr and nearly identical REE trends. All together, these features point to an analogous volcanic-arc-related magma source. This magmatism reflecting terminal stages of the accretionary wedge formation in the Mongolian Altai Domain may be related to the recently proposed late

The general SW–NE course of the Variscan orogen in Europe is abruptly bent to the N–S course at its eastern margin, where an oblique convergence occurred. The main suture in this part of the Variscan orogenic belt is called the Moldanubian Thrust, characterized by a dominant dextral strike-slip kinematics and a minor thrust component. The deep level of erosion and the good exposure of this structure allowed us to study the mechanisms of oblique convergence and the incorporation of the foreland basement into the orogenic belt. The combination of small-scale structures with the anisotropy of magnetic susceptibility studies allowed the recognition of two deformations in the studied rocks: dextral simple shearing and drag folding. Due to oblique convergence, the deformations induced by this mechanism were non-coaxial; therefore, their contributions can be easily distinguished. Finally, an overturned, almost recumbent large-scale synformal fold structure in the footwall and an antiformal structure in the hanging wall of the Moldanubian Thrust were formed. These two folds can be interpreted as structures formed by dragging along the Moldanubian Thrust. The previously described sinistral simple shearing in the upper limb of the synform resulted from the original dextral strike-slip shearing, which was overturned during progressive deformation.

The Trans-Altai Zone in the southern tract of the Central Asian Oceanic Belt is composed of Early Palaeozoic oceanic crust preserved in Ordovician to Devonian ophiolite fragments and Devonian-Carboniferous igneous arcs. The Edren and Baaran subzones at the NW tip of the Trans-Altai Zone were intruded by Late Palaeozoic plutons that have been examined by the combined geochronological and geochemical study.Mississippian subduction-related plutons intruded Devonian and Carboniferous volcano-sedimentary sequences in two magmatic pulses. The older, Tournaisian plutons (dated at 352 +/- 1 and 347 +/- 4 Ma) occur in both subzones; the younger Visean/Serpukhovian ones (331 +/- 1 Ma) are found only at the northern boundary of the Edren Subzone. All Mississippian rocks are high-K calc-alkaline and characterised by a strong enrichment of hydrous fluid mobile lithophile elements over conservative Nb, Ta and Ti relative to normal mid-ocean ridge basalts. Low 87Sr/86Sri (similar to 0.7035-0.7038) and highly positive epsilon iNd values (+ 6.6 to + 5.2) suggest a relatively juvenile parental magma source with a short mean crustal residence. This corresponds well with the age of scarce inherited zircons, none of which is older than 530 Ma.The Early Permian post-tectonic plutons intruded the shallow crust of the Baaran Subzone (Devonian-Carboniferous flysch and Early Carboniferous volcanic arc). The prominent concentric body of the Aaj Bogd Pluton is composed of monzodiorites to monzogabbros (284 +/- 1 and 294 +/- 3 Ma) in its centre, surrounded by granite with syenite (282 +/- 1 Ma) in the main mass of the pluton. Whole-rock Sr-Nd isotopic ratios match those of Carboniferous magmatic rocks, while trace-element patterns point to an intra-plate origin influenced by a fertile asthenospheric mantle component. On the other hand, the slightly older (290 +/- 1 Ma) quartz syenites to alkali feldspar granites in the Baaran Subzone have spurious arc-like geochemistry inherited from their arc-related crustal source(s). Regional distribution of the numerous oval-shaped Early Permian alkaline post-orogenic plutons, some with A2-type granite affinity, follows the major Permian strike-slip zones spanning from the Dulate Arc in the west to the Khan Bogd Pluton in the east. These late, transcurrent zones apparently played an important role in late-orogenic magma generation, ascent and emplacement.

In this study, U-Pb ages and Hf isotopic composition of detrital zircons from the Precambrian metasedimentary autochthon of the Brunovistulian Domain in the eastern Bohemian Massif were investigated to understand the pre-collisional evolution of the eastern periphery of the European Variscan belt. Detrital zircons of the Tonian sequences have mostly Paleoproterozoic to Neoproterozoic ages (c. 2.1-0.9 Ga) and are interpreted as detritus derived from the basement of either Baltica or Amazonia. The mostly positive epsilon Hf(t) values (-4 to + 16) indicate a juvenile nature of their magma sources with minor older crustal components. In contrast, the Ediacaran se-quences contain dominantly Neoproterozoic zircons (c. 600 Ma) and only rare Paleo-and Mesoproterozoic ages indicate that they were sourced from the adjacent Neoproterozoic magmatic arc with very limited input of recycled cratonic detritus. The large spread of epsilon Hf(t) values (-15 to + 13) of the Neoproterozoic zircons suggests significant mixing of mantle-derived magmas with mature crustal material, typical of large continental magmatic arc systems. The zircon age patterns of the Ediacaran sequences, characterized by a dominance of the late Neoproterozoic zircons and limited Mesoproterozoic zircons, are nearly identical to those from the Tepl'a-Barrandian Unit and Moldanubian Zone, pointing to their similar sources. We consider such age populations as a record of sources actually exposed at the time of deposition, rather than the real provenance signature of the continental basement. The change in detrital zircon U-Pb age and Hf record of the Brunovis-tulian Domain took place between the early and late Neoproteorozoic, and probably reflects the plate-tectonic reconfiguration from the Rodinia formation/break-up to the evolution of the Gondwana or Baltica active mar-gins. Our data challenge the main arguments for an existence of the Rheic oceanic suture between the Bruno-vistulian Domain and Moldanubian Zone and allow for an alternative pre-collisional model of the Bohemian Massif as a single Neoproterozoic crustal domain.

The geological map L-47-V at a scale 1:500,000 covers part of Mongolian Altaids with ophiolite fragments in southern Central Asian Orogenic Belt in SW Mongolia. This region has a basin and range topography with Neoproterozoic and Palaeozoic units exposed at NW–SE trending ranges rising along major intracontinental faults and with intermontane basins filled by Mesozoic and Cenozoic sediments in between. The map shows clear N–S tectonic zonation featuring the northerly Precambrian Baidrag microcontinent, the lower Palaeozoic Lake Zone in the centre and the southerly Palaeozoic Gobi-Altai and Trans-Altai zones. Gravity highs are located in the SW part of the map and low to intermediate Bouguer anomalies in the NE part. NW–SE trends of gravity anomalies correlate well with the contact between the Trans-Altai and the Gobi-Altai zones but the important first-order geological boundary between the Lake and Gobi-Altai zones cannot be delineated by the gravity gradients.

A new occurrence of Permian volcanic and volcaniclastic rocks in the Mongolian Altai south of the Main Mongolian Lineament was described between soums of Tugrug and Tseel in Gobi-Altai aimag. Studied vitrophyric pyroxene basalt lies in a layer of agglomerate and amygdaloidal lavas, which is a part of NE–SW trending subvertical sequence of varicolored siltstones and volcaniclastic rocks in the Tsengel River valley. This high-Mg basalt is enriched in large ion lithophile elements, Pb and Sr and depleted in Nb and Ta. LA-ICP-MS dating on 44 spots reveals several concordia clusters. The whole rock geochemistry of sample fits volcanic arc characteristic in the geotectonic discrimination diagrams. Dominant zircon data yield Upper Carboniferous and Permian magmatic ages 304.4 ± 2.3 and 288.6 ± 1.9 Ma. Two smaller clusters of Upper Devonian (376 ± 4.7 Ma) to Lower Carboniferous ages (351.9 ± 3.5 Ma) indicate probably contamination of ascending magmatic material. Youngest Triassic age found in three morphologically differing grains reflects probably lead loss. Described high-Mg basalt lava represents sub-aerial volcanism in volcanic arc environment developed over the N dipping subduction zone in the southwestern Mongolia in the time span from Uppermost Carboniferous to Permian during terminal stage of its activity.

Rokytna conglomerates and breccias are grey to red, coarse- to very coarse-grained, clast-supported sediments (locally, the matrix-supported varieties may occur). They are poorly sorted with rounded to subangular pebbles, max. size of clast is about 50 cm (along the a axis). Conglomerates and breccias (Fig. 5-1) are facially monotonous, the material was derived from easterly situated geological units. Culmian rocks (greywackes, shales, conglomerates) dominate here (89–99 %), Devonian to Lower Carboniferous limestones (Spacek et al. 2002) are locally common (up to 6 %). Quartz, quartzite and magmatic rock clasts derived likely from the Brunovistulian units are variably distributed. They are exceptional at Meckov, but could be relatively common (up 3 %) in other exposures of the Rokytna Conglomerate.

The Brno Massif is the largest exposed part of the Brunovistulicum (eastern Bohemian Massif) representing Precambrian basement incorporated into the Central European Variscan Belt. Two well-known Cadomian granodiorite complexes of magmatic-arc origin are separated by N–S-trending belt of mafic rocks previously compared to ophiolite. This so-called Central Basic Belt is formed by a slightly metamorphosed volcanic part (Metabasite Zone) in the east and dominantly plutonic Diorite Zone in the west. Our new geological, geochemical and isotopic data including U–Pb zircon dating reveal two distinct Precambrian magmatic events within the Central Basic Belt preceding the Cadomian arc. The geochemical signatures of the dominant late Tonian (c. 730 Ma) tholeiitic basalts (\(\varepsilon_{\text{Nd}}^{725}\) = + 7.8 to + 6.7) in the Metabasite Zone suggest a direct derivation from a mantle source in an extensional setting. Also, the associated sporadic rhyolitic lavas and tuffs are primitive, showing a short mean crustal residence (\(\varepsilon_{\text{Nd}}^{ 7 2 5}\) = + 6.0 and + 5.7; \(T_{\text{DM}}^{\text{Nd}}\).2stg ~ 0.9 Ga). By contrast, the Cryogenian (c. 650 Ma) magmatism of the Diorite Zone clearly demonstrates features of a magmatic-arc origin. Rather primitive whole-rock geochemistry and radiogenic Nd isotopic signature (\(\varepsilon_{\text{Nd}}^{ 6 5 5}\) values typically falling between + 7 and + 6) show that this arc was either intraoceanic, or developed on recently accreted, immature mafic crust. Based on all the available data, three successive tectono-magmatic stages have been identified in the Brno Massif in the Neoproterozoic times (c. 730–600 Ma), as products of a single long-lived, multi-stage subduction system spanning nearly full Neoproterozoic supercontinent cycle from the break-up of Rodinia to the assembly of Pannotia.

The Dřinova Hill was named after “dřin”, which is Czech name for Cornelian cherry (Cornus mas), a shrub growing on arid calcareous soils. The quarry was originally opened for limestone mining, both the over- and the underlying non-lime rocks were exposed with the progress of the mining. Nowadays, the quarry is still active and produces different types of crushed stone, especially from the underlying granodiorite rocks.

A geological map is an indispensable tool for understanding the structure of the Earth's crust but high-quality geological maps are usually lacking in remote areas of mountainous Central Asia covered by vast deserts. The progress in remote sensing and geographical information system (GIS), as well as the advancement in analytical methods, have generated new challenges in producing modern geological maps in such regions. The presented 1: 50,000 geological map along the Sagsai River summarizes new and more accurate geological data from the geologically interesting region at the contact of the supracrustal and deep crustal Tugrug and Tseel units forming the metamorphosed accretionary wedge on the S and SW slopes of the Mongolian Altai. These geological units are formed by the lower Palaeozoic volcano-sedimentary sequences affected by Devonian Barrovian metamorphism ranging from lower greenschist to granulite facies. This metamorphic basement was subsequently intruded by the post-orogenic late Carboniferous Sagsai Pluton. The presented map shows complex relationships between different crustal levels of the metamorphosed accretionary wedge and post-tectonic intrusion evaluated using a GIS, numerical processing of remote sensing data as well as field documentation and laboratory studies.

Orthogneiss and meta-rhyolite bodies from different crustal levels of the Tseel Terrane in the Mongolian Altai were examined using multidisciplinary approach involving structural geology, whole-rock geochemistry and U-Pb zircon geochronology. The orthogneisses form sheet-like bodies parallel with dominant sub-horizontal metamorphic fabric which was heterogeneously verticalized along localized zones of deformation at boundaries of lower and middle crustal domains. Three samples of orthogneisses yielded Late Devonian LA-ICP-MS U-Pb zircon ages of 373 +/- 3, 377 +/- 5 and 379 +/- 2 Ma (2 sigma), which are interpreted as crystallization ages of felsic magmas. The meta-rhyolite displays poorly constrained, older U-Pb zircon ages of 380 +/- 4 and 403 +/- 5 Ma, which are also considered as intrusive. Whole-rock geochemistry, including relatively little fractionated REE patterns, as well as radiogenic whole-rock Nd and zircon Hf isotopic signatures point to a rather primitive source of the granitic protoliths. The high-K calc-alkaline chemistry and LILE over HFSE enrichments in the NMORB-normalized spider plots indicate an arc-related origin. Juvenile character of the studied rocks was confirmed by Nd and Hf crustal residence ages that are mostly 0.8-0.9 Ga. The origin of the metaigneous rocks is interpreted in terms of partial melting of Neoproterozoic to Cambrian magmatic arc-derived material, probably dominated by immature psammitic sediments (graywackes). This study brings important arguments that the orthogneisses do not represent an old crystalline basement previously assumed in the Mongolian Altai. A model is proposed suggesting formation of mature and layered continental crust by syn-orogenic melting of youthful volcanosedimentary wedge and emplacement of sub-horizontal syn-orogenic magmatic sheets at all crustal levels during crustal-scale vertical shortening. The vertical shortening was probably connected to lithospheric-scale extensional event associated with massive heat influx and emplacement of juvenile magmas at the bottom of the crust. It is suggested that this mechanism represents potentially a viable model for cratonization of accretionary systems worldwide.

Tectonic slices of microgranites are exposed in the Metabazite Zone along its boundary with the Diorite Zone of the Cadomian Brno Massif. Rock with granophyric texture was found SW of the Velka Baba Hill. Granophyre is composed of irregular intergrows of quartz and feldspars arranged around albite lath. Rounded quartz is also presented. The granophyre has a chemical composition of trondhjemite, trace elements geochemistry can be well correlated with composition of rhyolites forming layers in metabazalts. Both rocks have character of within-plate to ocean-ridge granites and granophyres are interpreted as subvolcanic equivalent of rhyolites.

New geological, geochemical and geochronological data characterize architecture and geodynamic evolution of the southern Baydrag continental margin in Mongolia. The structurally deepest Zamtyn Nuruu Complex is composed of highly deformed orthogneisses and amphibolites intruded by syn-tectonic diorites and gabbros. Geochemical affinity of the amphibolites varies from continental-arc to within-plate tholeiites, while the Grenvillean (948±6 and 941±11Ma) orthogneisses show features typical of magmatic-arc origin. The syn-metamorphic gabbros and diorites intruded coevally with the regional thermal event at 542±4Ma. Zircon Hf isotope and whole-rock geochemical data point to a primitive source of mafic rocks, most likely formed in Early Cambrian arc developed on Grenvillean basement. The overlying Alag Khadny subduction mélange contains eclogites and amphibolites with MORB affinity while lenses of orthogneisses (953±12Ma: zircon, 939±5Ma: monazite) reveal late- to post-collisional signature. The subduction event is dated by zircon at ca. 538±20Ma. The matrix of the mélange consists of metapelites and carbonates, most likely fragments of Neoproterozoic to Early Cambrian carbonate platform scrapped off the subducting plate during the mid-Cambrian accretion. The hanging-wall Khan-Taishir–Erdene Uul ophiolite is formed by Neoproterozoic pillow lavas, red cherts and associated ultramafic rocks, with gabbros dated at 973±12Ma. Taken together, the new data allow placing south Mongolian continental fragments into a geodynamic model of Rodinia formation, fragmentation and Palaeo-Pacific subduction initiation. The Zamtyn Nuruu Grenvillean arc is interpreted as a result of Mirovoi Ocean subduction beneath Rodinian margin, while the Early Cambrian diorites and gabbros testify initiation of supra-subduction magmatism of Palaeo-Pacific plate beneath continental fragment of Gondwanan, most likely Tarim affinity. These two events were separated by the development of Neoproterozoic passive margin probably associated with Rodinia fragmentation.

ABSTRACTThe Chandman massif, a typical structure of the Mongolian Altai, consists of a migmatite–magmatite core rimmed by a lower grade metamorphic envelope of andalusite and cordierite‐bearing schists. The oldest structure in the migmatite–magmatite core is a subhorizontal migmatitic foliation S1 parallel to rare granitoid sills. This fabric is folded by upright folds F2 and transposed into a vertical migmatitic foliation S2 that is syn‐tectonic, with up to several tens of metres thick granitoid sills. Sillimanite–ilmenite–magnetite S1 inclusion trails in garnet constrain the depth of equilibration during the S1 fabric to 6–7 kbar at 710–780 °C. Reorientation of sillimanite into the S2 fabric indicates that the S1–S2 fabric transition occurred in the sillimanite stability field. The presence of cordierite, and garnet rim chemistry point to decompression to 3–4 kbar and 680–750 °C during development of the S2 steep fabric, and post‐tectonic andalusite indicates further decompression to 2–3 kbar and 600–650 °C. Widespread crystallization of post‐tectonic muscovite is explained by the release of H2O from crystallizing partial melt. In the metamorphic envelope the subhorizontal metamorphic schistosity S1 is heterogeneously affected by upright F2 folds and axial planar subvertical cleavage S2. In the north, the inclusion trails in garnet are parallel to the S1 foliation, and the garnet zoning indicates nearly isobaric heating from 2.5 to 3 kbar and 500–530 °C. Cordierite contains crenulated S1 inclusion trails and has pressure shadows related to the formation of the S2 fabric. The switch from the S1 to the S2 foliation occurred near 2.5–3 kbar and 530–570 °C; replacement of cordierite by fine‐grained muscovite and chlorite indicates further retrogression and cooling. In the south, andalusite containing crenulated inclusion trails of ilmenite and magnetite indicates heating during the D2 deformation at 3–4 kbar and 540–620 °C. Monazite from a migmatite analysed by LASS yielded elevated HREE concentrations. The grain with the best‐developed oscillatory zoning is 356 ± 1.0 [±7] Ma (207Pb‐corrected 238U/206Pb), considered to date the crystallization from melt in the cordierite stability ~680 °C and 3.5 kbar, whereas the patchy BSE‐dark domains give a date of 347 ± 4.2 [±7] Ma interpreted as recrystallization at subsolidus conditions. The earliest sub‐horizontal fabric is associated with the onset of magmatism and peak of P–T conditions in the deep crust, indicating important heat input associated with lower crustal horizontal flow. The paroxysmal metamorphic conditions are connected with collapse of the metamorphic structure, an extrusion of the hot lower crustal rocks associated with vertical magma transfer and a juxtaposition of the hot magmatite–migmatite core with supracrustal rocks. This study provides information about tectono‐thermal history and time‐scales of horizontal flow and vertical mass and heat transfer in the Altai orogen. It is shown that, similar to collisional orogens, doming of partially molten rocks assisted by syn‐orogenic magmatism can be responsible for the exhumation of orogenic lower crust in accretionary orogenic systems.

The low-grade metavolcanic/volcanosedimentary complex of the Devonian Vrbno Group (Silesicum, NE Bohemian Massif, Czech Republic) occurs in two ~NE–SW trending belts, separated by tectonic slices of Cadomian metagranitic paraautochton. (1) The basic–intermediate lavas of the calc-alkaline Western Volcanic Belt came from a moderately depleted mantle \( \left( {\varepsilon_{\text{Nd}}^{370} \sim + 3} \right) \). Rare rhyolites (374.0 ± 1.7 Ma: 2σ, LA–ICP–MS U–Pb Zrn) were derived most likely from immature crust or by extensive fractionation of primary basaltic melts. The rock association is interpreted as a vestige of a deeply dissected continental arc. (2) The Eastern Volcanic Belt consists mainly of (nearly) contemporaneous (371.0 ± 1.4 Ma) felsic alkaline lavas with high HFSE contents, as well as high Ga/Al and Fe/Mg ratios, typical of within-plate igneous setting. The petrology and Nd–Sr isotopic data point to a high-T anatexis of a young metagranitic crust, resembling the Cadomian (Brunovistulian) basement, in a back-arc setting. The attenuated Brunovistulian lithosphere could have partially melted by the heat provided by the upwelling asthenosphere and/or underplating basic magma. (3) Finally, the region was penetrated by numerous subalkaline, MORB/EMORB-like dolerite sheets—a hallmark of the considerable crustal thinning.

During the geological mapping in the Boskovice Basin, two new palaeobotanical localities in Veverské Knínice and a locality in Veverská Bítýška have been found. The most abundant flora comes from the Veverské Knínice localities. Conifers dominate in the floral assemblage. Pteridosperms are also relatively common, whereas ferns and sphenopsids are rare. These localities are assignable to the Padochov Formation, Říčany Horizon of the Permian (Rotliegend, Asselian) age. The subsequent Veverská Bítýška Formation belongs still to the Asselian. This formation contains Chudčice Horizon that yields very poor conifer flora at the Veverská Bítýška locality. Permian system is a period of progressing aridity in Moravia. Only fossiliferous horizons represent spans with higher humidity that enabled plants to live. However, the climate was not so humid, but it was rather seasonal, because pure hygrophyte plants lack in the assemblage, on the other hand, “xerophyte” plants, like conifers, dominate here.