Intrusion of the Cambrian Burd Gol Granite Massif into the Proterozoic metamorphic rocks of the Zamtyn Nuruu and molasse-like sediments of the Boomyn Khudag Fm. culminated the collisional events of the Caledonian evolution in the SE part of the Lake Zone, Gobi Altay, SW Mongolia. The monotonous leucogranites of the Burd Gol Massif have a high-K calc-alkaline, subaluminous to slightly peraluminous geochemical signature with an intermediate initial Sr ratio ( 87 Sr/ 86 Sr 510 = 0.7064) and rather unradiogenic Nd (ε 5 Nd 10 = -1.5 and -0.2). The laser ablation ICP-MS U-Th-Pb radiometric dating of monazites and zircons from these rocks yields intrusive ages between 506.4 ± 5.4 and 513.4 ± 4.3 Ma (2σ). The final stage of magmatic activity is documented by the Ar-Ar dating of muscovite from a pegmatite dyke at 485.1 ± 3.2 Ma. The granites intruded and thermally influenced the terrestrial clastic sediments of the Boomyn Khudag Formation, whereby the thermal metamorphism of sediments was characterized by a muscovite growth. These new data argue against the previously assumed Permian age of the Burd Gol Massif and the Lower-Middle Devonian age of the Boomyn Khudag sedimentary formation and illustrates the terrestrial evolution in this part of the Lake Zone during the Cambrian.
As so ci ate Ed i tor-Anna Wysocka The en trenched Odra palaeovalley, cut into the bed rock of the dis tal mar gin (forebulge basal un con formity) of the Moravian Carpathian Foredeep (pe riph eral fore land ba sin) is filled with an al most 300 m thick pile of Mio cene de pos its. The directon of the val ley (NW-SE to NNW-SSE) has been con trolled by faults subparallel with the sys tem of sudetic faults". The sed i mentary suc ces sion con sists of 5 fa cies as so ci a tions/depositional en vi ron ments, which are in ter preted (from bot tom to top, i.e. from the old est to the youn gest) as: 1-col lu vial de pos its to de pos its of al lu vial fan, 2-de pos its of al lu vial fan, 3-fan-delta de pos its, 4-shal low wa ter delta to nearshore de pos its and 5-open ma rine de pos its. This fin ing-up and deep en ing-up succes sion re veals the fol low ing: the for ma tion of the new flex ural shape of the ba sin; deep ero sion con nected with up lift and tilting of the forebulge and re ac ti va tion of the NW-SE trending base ment faults; the Early/Mid dle Mio cene sea level fall; al lu vial de po si tion mostly driven by tec ton ics and mor phol ogy; forebulge flex ural re treat; Mid dle-Mio cene sea level rise; back-stepping of val ley infill; ma rine in va sion dur ing the Early Badenian with shift of the coast line fur ther land ward of the pallaeovalley. Tec ton ics re lated to con tem po rary thrust ing pro cesses in the West ern Carpathians are as sumed to be the dom i nat ing fac tor of the stud ied de po si tion at the ex pense of eustatic sea level changes. Prov e nance stud ies have proven that the pre-Neogene base ment (i.e. the Early Car bon if er ous clastic "Culmian fa cies" of the Moravian-Silesian Pa leo zoic) rep re sents an impor tant source for the con glom er ates and sands, which vol u met ri cally dom i nate in the palaeovalley infill. How ever, they also showed, that the de pos its of the ear lier Carpathian Foredeep Ba sin sed i men tary stage (Karpatian in age?) cov ered the area un der study and were eroded and resedimented into the palaeovalley infill.
The Cretaceous continental sedimentation in SW Mongolia was commonly accompanied by volcanic activity. Bimodal association of the Cretaceous Khulsan Gol Formation is represented mostly by calc-alkaline and rare alkaline volcanic rocks (basaltic andesite, trachybasalt to trachyandesite lavas or tuffs with lahars). The lavas were extruded mainly subaerially, although locally there is a subaqueous component present corresponding to final phases of Mesozoic sedimentation in the Gobi-Altay rift zone. Variations in chemical and isotopic composition reflect crustal assimilation coupled with fractional crystallization of parental magma generated by melting of lower lithosphere and/or uppermost asthenospheric mantle. These within-plate volcanic rocks can be explained as initial stages of Cenozoic magmatic activity in the Mongolia.
De vo nian siliciclastic rocks of the Babí lom lo cal ity (south ern Moravia, Czech Re pub lic): sed i men tary en vi ron ment re con struc tion and prov e nance study Jurand Anchimetamorphosed sand stones and con glom er ates of the so-called "Basal De vo nian Clastics", that build a hill (ridge) named Babí lom, are con sid ered to be of Lower to Mid dle De vo nian age. Al though they are strongly tec toni cally af fected, many sed i men tary fea tures are well-pre served and dis tinct. Both the fa cies and struc tures typ i cal of al lu vial fans and rivers were rec og nized in the sed i men tary as so ci a tion at Babí lom. Among oth ers, there are chan nel lags with imbricated grains, cross-bed ding, and debrites. The way-up di rec tion is clearly seen via re pet i tive coars en ing-up wards se quences. As sum ing a lack of ro ta tion of the suc ces sion in the X-Y plane, the main palaeodrainage was to wards the north and the ma jor sup ply of ma te rial was from the east. The high ma tu rity of the rocks sug gests der i va tion from older de pos its and/or highly weath ered source rocks. The mag matic rocks of the Brunovistulicum are pos si bly the pri mary source of the sed i ments.Key words: south ern Moravia, Brno Mas sif, De vo nian siliciclastics, fa cies anal y sis, heavy min er als, al lu vial fan. INTRODUCTIONIn Czech geo log i cal lit er a ture, the term "Basal De vo nian Clastics" is used for the red monomictic quartz-peb ble conglom er ates, quartz arenites, subarkoses, and ar kos es with interbeds of lam i nated siltstone, as well as for polymict conglom er ates which are ex posed in sev eral ar eas of south ern Moravia (e.g., Dvoøák, 1978, 1998Gilíková, 2007). These depos its have also been named the Old Red Sed i ments (Skoèek, 1980;Zukalová and Chlupáè, 1982). The best known oc currences of these clastics are in the Moravian Karst area, between Bílovice nad Svitavou and Ochoz u Brna (Gilíková et al., 2010), in the Babí lom -Èervený kopec Zone be tween Svinošice and Lelekovice, and in the Èebínka Zone near the town of Tišnov (Hanžl et al., 2007). These rocks are also known from nu mer ous deep bore holes along the south east ern mar gin of the Bo he mian Mas sif (Vavrdová et al., 2003;Mikuláš et al., 2008).Spec tac u lar out crops of De vo nian clastic rocks in the Babí lom des ti na tion (Fig. 1) have at tracted the in ter est of a num ber of in ves ti ga tors (Dvoøák, 1960;Melichar et al., 1999;Nehyba et al., 2001;Gilíková, 2007;Buriánek et al., 2008). The aim of this pa per is to pres ent re sults of sedimentological and pet ro graph ical stud ies car ried out in sev eral iso lated ex po sures in this zone, that ad dress the ques tions of: -depositional pro cesses and set tings, -evo lu tion of the depositional en vi ron ment, -source ar eas, -and dem on strate ap pli ca bil ity of sedimentological techniques in tec toni cally de formed coarse clastic. GEOLOGICAL SETTINGThe siliciclastic sed i men tary rocks of the Babí lomÈervený kopec Zone crop out over the N-S elon gated area bordered ...
Type sections/areas for all four formations distinguished in the sedimentary succession of the Subsilesian Unit on Czech territory were revisited and described. New data on lithology, sedimentology, fossil record, biostratigraphy, heavy-minerals and geochemical proxies are based on observations and analysis of these sections. The historical type section of the Frýdek Formation was destroyed during railway construction in 19th century. Outcrops of Campanian to Maastrichtian marls and sandstones on the southwestern slope of “Castle hill” at Frýdek, are proposed as a new type section. The Ostravice riverbed in Frýdlant nad Ostravicí was originally designated as the type area, not mentioning the particular section. This area, even when supplemented with Sibudov Creek, does not show all typical facies of the formation. The outcrops range from lowermost Eocene to Eocene-Oligocene transition. In the original description of the Menilite Formation Glocker mentioned several localities in the area covering the Ždanice, Subsilesian and Silesian units, not mentioning the principal one. The single sections, each not exceeding a thickness of 2 m, are not sufficient to be a type section. Instead of that, we propose the area between Paršovice and Bystřice pod Hostýnem, covering the historical localities, as the type area. The type locality of the Ženklava Formation is an outcrop in an unnamed creek in Ženklava according to the original definition. It seems to be reasonable to extend the type section to the whole 500 m long section of the creek with the outcrops that better illustrate the lithological variability of the formation. New biostratigraphic data allow assignment to late Egerian (Eggenburgian?).
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