The results of paleostress analyses in the eastern parts of the Nízký Jeseník and the Drahany Uplands

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1 The results of paleostress analyses in the eastern parts of the ízký Jeseník and the Drahany Uplands Vìstník Èeského geologického ústa!::u 75, l, 2000 JOSEF HA viø Ostav fyziky Zemì, PøF MU Brno, Tvrdého 12, Brno, A b str a c t. The orientation of the principal paleostress axes were studied in the Culmian sediments ín the eastem partsof the ízký Jeseník area (the Moravice and the Hradec-Kyjovice Formations) and ofthe Drahany Uplands (the Myslejovice Formation). The paleostress analyses were based on the fault geometry investigation. Several different Variscan paieostress fields were computed. In the case of compressional stress fields with subvertical oríentation of the maximum extension, the axis of maximum compression (JI were orientated from E- W to W -SE, in south-eastem part of the Drahany Uplands up to W-SSE. In some cases, both the maximum compression axis and the maximum extension axis are orientated sub-horizontally. The axis of (JI was orientated E-SW or E- W, axis of (JJ was orientated W -SE or -S. But at one síle (the site 26) in the eastem part of the ízký Jeseník area the inverse orientation of the (JI axis and the (JJ axis were aiso computed. The extensional paleostress fields were computed only in the ízký Jeseník area. The maximum extension axes were orientated approximately E- W (in wide range of orientations from W -SE up to E- SW). The orientations of the tensile fractures and the quartz veins measured in the eastem part of the ízký Jeseník area do not agree to this result. The facts discussed in the article indicate the generally Variscan age of the found compressional stress fields. The younger extensional stress fields are probably late- Variscan and they can reflect the gravitational collapse of the Variscan orogene. A b str a k t. V kulmských sedimentech východní èásti ízkého Jeseníku (moravické a hradecko-kyjovické souvrství) a Drahanské vrchoviny (myslejovické sou vrství) byla studována orientace hlavních os paleonapìtí. Paleonapì ová analýza byla založena na studiu geometrie zlomù se striacemi. Bylo zjištìno nìkolik rùzných paleonapì ových polí. V pøípadì kompresních napì ových polí se subvertikální orientací maximální extenze byla osa maximální komprese orientována ve smìru V-Z až SZ-JV, v jižní èásti Drahanské vrchoviny až ve smìru SSZ-JJV. V nìkterých pøípadech byly jak smìry maximální komprese, tak i smìry maximální extenze orientovány subhorizontálnì. Osa 0"\ byla orientována ve smìru SV -JZ nebo až V- Z, osa 0"3 pak ve smìru SZ-JV nebo S-J. a jedné z lokalit ve východní èásti ízkého Jeseníku (lokalita 26) však bylo spoèítáno také paleonapì ové pole s obrácenými orientacemi os 0"1 a 0"3. Extenzní paleonapì ová pole byla zjištìna pouze v ízkém Jeseníku. Smìr maximální extenze byl pøibližnì V.-z. (s širokým rozptylem orientací od smìru SZ-JV po smìr SV-JZ). S tímto výsledkem nesouhlasí orientace tahových puklin a køemenných žil, které byly mìøeny v regionu ízkého Jeseníku. Skuteènosti diskutované v tomto èlánku ukazují obecnì variské stáøí zjištìných kompresních napì ových polí. Mladší extenzní paleonapì ová pole jsou pravdìpodobnì pozdnì variská a mohou být odrazem gravitaèního kolapsu variského orogenu. Ke y word s: brittle deformation, faults with striations, paleostress analyses, ízký Jeseník area, Drahany Uplands, Variscides lntroduction The Lower Carboniferous Culmian sediments depositeï at the eastem boundary of the Bohemian Massif (in the Moravian-Silesian region) belong to the extemal domain of the Variscan orogene. They have been proposed to be a part of the Rhenohercynian za ne (for instance Behr et aj. 1984). There are two main outcrops of the Culmian sediments (shales, graywackes and conglomerates) on the eastem margin of the Bohemian Massif: the ízký Jeseník and the Drahany Upland areas. These sediments represent a flysh and Jater an early molasse of the Variscan oroge- The age and deformation of the Culmian sediments decrease generally from west to east or from north-west to south-east in the Moravian-Silesian units (Dvoøák 1973, 1993, 1994; Hrouda 1979; Kumpera 1972). In Dvoøák's (1993) opinion, the Culmian sedimentation started in the Andìlská Hora Formation (the western part of the ízký Jeseník Uplands) already during the Famennian. The age of sediments decreases eastwards through the Tournaisian and Viséan up to amurian in the eastern part of the ízký Jeseník Uplands. The Culmian sediments were folded during Variscan deformation, the fold axes and strike of the cleavage planes are predominantly orientated approximately E- SSW in the Moravian-Silesian region (Dvoøák 1973, 1993; Kumpera 1983). Cháb (1986) supposes the nappe fabric of the Culmian units. Some evidence of the nappe fabric was shown by some other authors (for instance Èížek, Tomek 1991; Melichar, Buèek 1994). Stress analyses based on the fau1t geometry investigation were carried aut in the eastern part of the ízký Jeseník Upland by Grygar (1991). Both the axes ofmaximum compression (0"1) and extension (0"3) computed by his analyses were subhorizontal. The axis 0"1 was orientateï in WW-ESE direction, 0"3 was orientated in E- SSW direction in the Jakubèovice quarry. Hanžl (1997) distinguished several different stress field analyses at sites in the Brno pluton. Only some from the distinguished stress field are considered to be Variscan age. Hanžl supposes the post-variscan age of the E-SW extension, the E-W compression also could be post-variscan. ew results of the paleostress ana}yses based on the fault geometry investigation, carried aut in the eastern parts of the ízký Jeseník area (the Moravice and the Hradec- Kyjovice Formations) and of the Drahany Uplands (the Myslejovice Formation), are discussed in this article. 27

2 Bulletin ofthe Czech GeologicaJ Survey 75, 1,2000 o Km cr,\\. '..'.' ,-'1 ".,; cī!::> I : ::::Jlli!\\ O" '" '>- H,,: ;:: ;jj;' 0", <:,,, '""" '? t ple Angelier-Mechler's method t of graphical analysis (Angelier, Mechler 1977). Four sub-regions for common stress analyses of the measured data were single aut in the eastern part of the ízký Jeseník area (see fig. 1). Sub-region A is created by sites in the valley of Bystøice river, southwards of Domašov n. Bystøicí, in the western part of."; the investigated area. At these si- : tes the rocks of base of the Moravice Formation Tise on surface. Sub-region B contains the sites south-eastwards of Vítkov (the Hradec-Kyjovice Formation " and the most upper part of the \t? Moravice Formation). Two subregions were single aut in the val- 'lili,. ) ley of Moravice river in the nort- 3 hern part of the investigated area. Sub-region C is situated in the eastern part of this area, near Hradec n. Moravicí, sub-region D was single aut in the western part, northwards of Vítkov. In the southeastern part of the Drahany tp Principal Faults Uplands, Only one sub-region -. : I ' Front 01 Principal named E was single aut., 4 Us TRIA (" appes On ly at some sites it was pos- cr3 E3 Lugian and sible to carry aut a separate stress West Car pathians Bohemian Massif Jurassic Moldah.ubian. analysis. At these sites the nume- crystalllne urnts ncal results were com p uted usmg :g Outer Flysch Belt Tertlary.Quaternary Permlan Moravo-Slleslan volcanic rocks crystaillne urnts.the program IVERS made by 0"3 D eogenesedientsol eogene -Devonian-Carbonilerous Varlscan granrtolds S erner et al. (1993) and the prothe Vienna Basln and sedlmentary -..p thecarpathian E1 Cretaceous andvolcanicrocks Cadomlanlgneous gram BRUTE3 made by F d rocks. are eep Hardcastle and Hllls (1991), Fig. I. Schematic geologicai map of the eastern margin of the Bohemian Massif and the results of the which are based on the inversion simple graphicai Angelier-Mechler's method of the paleostress analysis (Lambert projection, lower method (Angelier 1984; 1989). hemisphere, 0"1 -horizontal hatching, 0"3 -vertical hatching). A-E are sub-regions single aut for common Both programs computed variabsimple stress analyses (see text). les of the reduced stress tensor (Angelier et al. 1982). It means, the orientations of the principal axes (0"1, 0"2 and 0"3) and the value of the stress Paleostress ana1yses ofthe data ratio 0=(0"2-0"3).(0"1-0"3)-1 (defined by Angelier 1975) were computed. But the accuracy of the calculation of the The paleostress analyses were based mainly on the in- stress ratio was too low. Thus only the computed orientavestigation of fault planes with striations and other kine- tions of the principal stress field axes are discussed in this matic indicators in the Culmian rocks in the eastern parts article. of the ízký Jeseník and of the Drahany Uplands. The The kinematic indicators on the micro-fault planes ofmeasurements of the quartz dikes and extensional fractu- ten show strongly various character of movement. les were used less often. Somewhere, the reversed and normal faults and strike Planes of micro-faults with striations were found at a slips, which cannot be created in the same stress field, wenumber of sites, mainly in the eastern part of the ízký re found at same site. After separation of data sets, more Jeseník area. But the number ofmeasured data were often different stress fields were found in the eastern parts ofthe insufficient at a single sites. That is why the data from si- ízký Jeseník area and Drahany Uplands. Some of them tes near each other were analysed together using the sim- represent the Variscan compression, other stres s fields 28 f'..i, r

3 Vìstnik ÈeskéboKeoloKickébo ústavu show probably late- V ariscan or post- V ariscan extension. Compressional paleostress fields Compressional paleostress fields with subvertical orientation of the axis of maximum extension (0"3) were found both in the ízký Jeseník area and Drahany Uplands. The orientation of maximum compression 0"\ computed in separated sub-regions various from E-W to W-SE (fig.l). The orientation E-W or WW-ESE were found in the sub-regions C (ji" and D in the north-easternern part of the ízký Jeseník area. Result of stress analysis in the sub-region o Km a, a, i?. + a, O.ofsite: a, o. ofsite: 192.-::::: '\\.; +"\ o. -'J( I:.J o((f,o. ofsite: 21 B (south-eastern part ofthe ízký..'+ ;"", Jeseník area) shows orientation of 0"1 rather in direction W-SE. I " , ++.' >ht Common stress analysis of the " fault striations in the south-eastern part of the Drahany Uplands gave two different results of compressi- : onal paleostress fields with subvertical orientation of the axis of maximum extension 0"3. First resuit shows orientation of 0"\ approximately in direction from WW- ESE to W -SE, second result A U STR I A Other paleostress fields con- nected with the Variscan com- planes). pression show sub-horizontal shows trus orientation rather in di-.fig. rectlon W -SSE. orientation both axis 0"1 and axis 0"3. This paleostress field were found in the sub-region C in the eastern part of the ízký Jeseník. The axis of maximum compression 0"1 is orientated in direction E-SW, axis of maxim extension 0"3 is orientated in direction W- SE. Same orientations r:: +) \ ":;; ) ] o. ofsite: 120 o. ofsite: 108 t })o.ofsite: Principal axes ofpaleostress field:.a, maximumofcompression Á a, intennediate axis.a, maximum of extension 2. Schematic geological map of the eastern margin of the Bohemian Massif (legend is same as in fig. I) and the orientations of principal paleostress axes (arrows represent orientation of principal horizontal stresses) -compressional paleostress fields (Lambert projection, lower hemisphere, great circles -fault of principal axes of paleostress field were found also in the south-eastern part of the Drahany Uplands. But in this sub-region E also another stress field with orientation of 0"1 in direction W-E and with orientation of 0"3 in direction -S was singled aut (fig. I). Results of the common analyses in separated sub-regions agree to some results of numerical analyses carried aut at single sites in the eastern part of the ízký Jeseník area (fig. 2). Subvertical orientation of 0"3 and axis of 0"1 orientated in direction E-W and W-SE follows from analyses carried aut at sites I and 21. Paleostress field with axis of 0"\ orientated in direction E-SW and axis of 0"3 orientated in direction W-SE was found at site 25 north-eastwards of Vítkov. This field agrees to result from sub-region D. otwithstanding, the strongly different result, with opposite orientations of {J] and {J3, follows from kinematic indicators found at some micro-fault planes at site 26, southwards of Domašov n. Bystøicí (the sub-region A). Unfortunately, small number of measurements and existence another strikeslip faults with opposite character of movements at site 26 bring some uncertainty into result of analysis at this site. umerical paleostress analyses were carried aut also at three single sites in the south-eastern part of the Drahany Uplands (sites 102, 108 and 120). At the site 102, the principal axes orientations are similar to orientations at the site 25. The axis of maximum compression {Jj is orientated in direction E-SW, axis of maximum extension {J3 is orientated in direction W-SE (fig. 2). Another result was computed at the site 108. The axis of maximum compression {J] is orientated in direction E- W or EE- WSW and the axis of maximum extension {J3 is orientated in direction -S or W -S SE. The subvertical orientation of {J3 and axis of {J] orientated approximately in direction W-SE were found at the site 120. These re ; '?!;,'-f: K; "::,.; '*:

4 Bulletin ofthe Czech GeolopJcal S!![vey o Km x o. -'o. or site: 32 C1,r..1;::3 ofsite: 24" ty and their orientation very well t retlects the orientation of maximum extension. But the planes are often pre-existing and their poles could differ from the orientation of principal extensional stress axis. The range of the orientation differences of the quartz...,,"! mineral fibres on the fracture planes and the pole of this planes visible at some sites is up to value ]i1j 200 in the eastern part of the ízký Jeseník area. The ma:ximum of density distribution of the fracture poles is, ' ", orientated in direction from -S q ;;,, to E-SSW (fig. 4). AIso poles r of quartz veins are predominant- " ly south-dipping (fig. 4). It can indicate rather -S extension, o. ofsite: 5 while results of normal fault geo- metry analyses show rather E- W?J> :c extension. AUSTRIA o. ofsite: Principal axes of pa1eostress field: fields Ages of found paleostress.(j, maximum of compression Á (J, inteediate axis.important question is age of (J, maxlmumofextenslon found stress fields. Some infor-fig. 3. Schematic geological map of the eastern margin of the Bohemian Massif (legend is same as in fig. mation about relative ages of the I) and the orientations of princi pal paleostress axes (arrows represent orientation of princi pal horizontal stress fields can be obtained from stresses) -extensional paleostress fields (Lambert projection, lower hemisphere, great circles -fault pla- the study of relationships of difnes). ferent products of brittle deforsults agree to mentioned results obtained from common mation. At a few sites it was rasimple graphical analyses in this slib-region E. rely possible to see two different generations of striations on same fault planes. The striation showing oblique re- Extensional paleostress fields versed movement along the fault plane is covered younger rather strike-slip striation at site I in the southeastem part Micro-fault planes with striations proving the existen- of the ízký Jeseník area, south-eastwards of Vítkov. ce of the extensional stress fields with subvertical orienta- Similarly, the younger striation showing normal movetion of axis of maximum compression (JI were found auly ment covers the older strike-slip striation on the fault plain the ízký Jeseník area. The orientations of axes ofma- ne at site 32 northwards of Vítkov. AIso the quartz mineximum extension (J3 strongly differ from place to place. ral fibres indicating the younger tensile movement on the Significant differences are visible mainly from results of some predominantly E-W orientated fault planes with kiseparated numerical analyses at some single sites. The nematic indicators of the older sinistral strike-slip moveaxis of (J3 is orientated approximately in direction E- W at ment is important for study of relative age of stress fields. sites I and 24, at site 5 the W-SE extension was found The crossing of different planes (faults, fractures and and at site 32 the E-SW extension follows from analysis veins) can give another important information about rela- (fig. 3). tive age of the stress fields. For example the crossing of Also extensional fractures with quartz mineralization tensile fractures and reversed fault planes was found at siand quartz veins gel evidence about extension in the eas- te 21 in the valley of Moravice river in the eastem part of tem part of the ízký Jeseník area. But it is necessary to draw attention to the fact lhal the orientation of maximum the ízký Jeseník area. Absence of any offset of parts of tensile fractures crossing the reversed fault plane proves extension is parallel to the orientation of the minerl fib- the younger age of tensile fractures. At the same site the res on the fracture plane rather lhali to the pole of thls pla- ne. The mineral fibres grew during the stress field activi- crossing quartz vein and a few normal and reversed faults was observed. The quartz vein is shifted along the normal íí- -::::k::; ; 1 30

5 "'" ---, R31 Vìstnik Ceského J!eo1oJ!ického ústavu Equal Area (Schmidt) age of the found compressional stress fields. The younger extensional stress fields connected with tensile fractures and normal faults are probably late- Variscan and they can reflect the gravitational collapse of the Variscan orogene. But the post-variscan (saxonian) age ofyounger stress fields cannot be excluded on base of discussed results. Conclusion Fig. 4. Diagram of the poles of fractures with quartz mineralization (circles) and the poles ofthe quartz veins (squares) -the eastem part of the ízký Jeseník area (Lambert projection, lower hemisphere). fault planes, blit no movement along the reversed fault planes was found. The relationships of different products of brittle deformation show the generally oldest age of compressional stress fields obtained from analyses of reversed faults, younger age of the stress fields with subhorizontal orientations of maximum compression axis (JI and of maximum extension axis (J3 represented by the strike-slip faults and youngest age or extensional stress fields connected with normal faults. The tensile fractures are probably generally younger than strike-slip faults and older than normal faults. This distinguishing of relative ages, based on the observation of relationships of different products of brittle deformation, is on ly schematic, the existence more different generation of fault planes with similar orientation and sen se of movements could be possible. The Culmian sediments were folded during Variscan deformation in the eastern part of the ízký Jeseník area. Variscan folding involved also fault geometries at some sites. For example fault planes found in arm of large fold at site 17 near Hradec n. Moravicí were rotated together with the sedimentary layers during folding. Before the rotation the fault geometries had character of sinistral strikeslip and reversed faults. This relationship pro ves Variscan age of found rotated faults indicating compressional stress fields. Similarly the close orientations of maximum compression (JI, cleavage poles and the minimum axis offinal fabric ellipsoid of deformed Culmian conglomerates at site 21 can indicate Variscan age of compressional stress field obtained from analysis of reversed micro-faults found at this site. The discussed facts indicate the generally Variscan The results of stress analysis in the eastern parts of the ízký Jeseník area and Drahany Uplands show the existence of some different stress field. There is evidence of the Variscan age of the compressional stress fields. The axis of maximum compression (J\ of stress fields with subvertical axis of maximum extension (J3 were orientated in direction from E-W to W-SE, in south-eastern part of the Drahany Uplands up to W-SSE. Other compressional stress fields connected with the Variscan compression show sub-horizontal orientation both axis (JI and axis (J3. The axis of (JI was orientated in direction E-SW, axis of (J3 was orientated in direction W -SE. In addition, in the southeastern part of the Drahany Uplands another stress field with orientation of (JI in direction W-E and with orientation of (J3 in direction -S was found. The stress analyses of younger predominantly normal micro-fault geometry show rather E-W orientation of the axis of maximum extension (in wide range from W-SE up to E-SW). The orientation of tensile fracture poles and quartz veins do not agree to this result. The maximum of density distribution of the fracture poles is orientated in direction from -S to E-SSW. 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6 ()unetin ofthe Czech Geo1ogicaJ Survey 75, 1,2000 eastern boundary of the Bohemian Massif. -Tectonics, 10,2, Dvofák, J. (1973): Synsedimentary tectonic of the Palaeozoic of the Drahany Upland (Sudeticum, Moravia, Czechoslovakia). - Tectonophysics, 17, Amsterdam. Dvofák, J. (1993): Moravské paleozoikum. -In: Pøichystal, A. - Obstová, V. -Suk, M. (eds.): Geologie Moravy a Slezska, 41-58, Morav. zem. muz. Brno. Dvofák, J. (1994): Variský flyšový vývoj v ízkém Jeseníku na Moravì a ve Slezsku. -Èes. geol. úst. Praha. Grygar, R. (1991): Strukturnì-kinematická analýza sv. okraje Èeského masivu. -Záv. zpráva HS 105/90. -MS archív VSB. Ostrava. Hantl, P. (1997): Structural profile through the Brno Massif. -Exploration Geophysics, Remote Sensing and Environment, IV, 1, Hardcast1e, K.C. -Hil1s, L.S. 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(1993): Fault-striae analysis: a Turbo Pascal program package for graphical presentation and reduced stress tensor calculation. -Computers & Geosciences, 19, 9, RECEZE H Lobitzer -P. Grecula (editoøi, 1999): Geologie ohne Gtenzen. Festschrift 150 Jahre Geo/ogische Bundesansta/t. - Abhandlungen, 56, 1,460 str., Geologische Bundesanstalt, Wien. a jiném místì jsme ve Vìstníku Èeského geologického ústavu informovali o 150. výroèí založení Rakouské geologické služby a o oslavách tohoto neobyèejnì významného jubilea. Souèástí tìchto oslav bylo i vydání sborníku prací v kmenovém periodiku vídeòského geologického ústavu. Sborník byl pøipravován již v polovinì roku 1998 a rozvržen tak, aby obsahoval jednak èást historickou, jednak odborné èlánky s tématy vìdecké spolupráce Rakouska s okolními zemìmi. Rukopisù se postupnì nahromadilo tolik, že tento sborník musil být rozdìlen do dvou èástí. První vyšla vèas a byla k dispozici úèastníkùm oslav v listopadu Rakouští pøátelé, pouèeni tím, že podobné títuly jako "Sborník k výroèí spolupráce" jsou komerèním propadákem, tentokráte nazvali svazek chytøe "Geologie bez hranic". To mùže naopak zájem pøípadných konzumentù pøilákat. Editoøi rozdìlili první svazek na nìkolik sekcí: Po úvodním slovì øeditele ústavu následuje blok s pøíspìvky zástupcù okolních zemí o dìjinách geologické spolupráce s Rakouskem. Druhý blok se soustøedil na nìkterá speciální témata z historie geologických výzkumù. ásleduje èást zahrnující geologické pøíspìvky, popisující výsledky mezinárodních výzkumù rakouského krystalinika a staršího paleozoika. Poslední èástí jsou "varia", smìs tematicky rùznorodých geologických statí. a následujících øádcích postupnì probereme charakter jednotlivých sekcí. Pøedešleme jen, že sborník je dvojjazyèný, èást je publikována nìmecky, èást anglicky. Všechny èlánky pak mají nìmecký a anglický abstrakt. Èlánky do historické èásti byly pøímo objednány oslavencem, Rakouskou geologickou službou. Editoøi pøitom ponechali na vùli autorù, jak tyto pøíspìvky pojmou. Švýcaøi pojednali o pøíkrovové stavbì Alp a o úloze rakouských geologù pøi tektonických studiích. Zástupce Bavorska psal sice též o Alpách, soustøedil se však spíše na biostratigrafické studie v druhé polovinì minulého století. ezùstal jen pøi historii, nýbrž vìnoval se i moderním koncepcím deskové tektoniky. Èeský pøíspìvek je ponìkud odlišný. Jde spíše o esej, nebo si vybral nìkolik zajímavých témat rakousko-èeských vztahù: osobu Franze Eduarda Suesse a jeho pøedstavu moldanubického nasunutí pøes moravikum, osudy bloku ortocerového vápence z Kosova, práci rakouských a èeských geologù na Blízkém východì, vztahy mezi hornickými akademiemi v Leobenu a Pøíbrami a nápadnou faunistickou pøíbuznost mezi silurem Karnských Alp a Barrandienu. Èeský pøíspìvek obsahuje i seznam 127 geologù a pøírodovìdcù, kteøí do roku 1918 mìli úzké vztahy jak k Rakousku, tak k Èeským zemím. Slovenský pøíspìvek je velmi struèný a bohužel ho nenapsal zamìstnanec spøátelené geologické služby. Maïaøi a Slovinci se vìnovali historii spoleèných geologických výzkumù a svá pojednání vyzdobili portréty, ukázky rukopisù a starých map. Podobnì je koncipován i italský pøíspìvek. Z Bosny a Hercegoviny došel rukopis, který je vlastnì biografií rakouských geologù, geografù a montanistù, pracujících v této balkánské zemi, patøící kdysi k monarchii. Druhá èást sborníku je historicko-biografickou všehochutí. Obsahuje krátké èlánky o nìkterých osobnostech nebo událostech. ìkteré z nich popisují vyloženì "vnitøní záležitosti" Rakouska, jako tøeba vztahy mezi Geologickou službou a univerzitou ve Štýrském Hradci. Bylo sem zaøazeno i pojednání o Joachimu Barrandovi, jehož úzké vztahy k Vídni byly obšírnì popsány v jiných pub)ikacích. Do tøetí sekce sborníku jsou zaøazeny spoleèné práce, týkající se krystalinika a staršího paleozoika. Pomohli ji naplnit i naši autoøi. Jeden z nich popisuje silurské a spodnodevonské mlže Kamských Alp, druhý spolupracoval na výzkumu silurských èerných bøidlic téhož regionu a tøetí studoval dvojsiídné žuly jihoèeského plutonu. Ostatní pøíspìvky se týkají krystalických vápencù Štýrska, metamorfovaných bazaltù Solné Komory a silurských nautiloidù Karnských Alp. Do poslední sekce byly zaøazeny rukopisy, které byly v termínu redakènì zpracovány. I zde má Ceský geologický ústav své zastoupení, a to v èláncích o miocenním vulkanismu. Jinak jde o skuteènou smìs petrografických a paleontologických prací z Rakouska i zahranièí. Z této struèné recenze vyplývá, že spoleèným jmenovatelem vydaného sborníku je starší i souèasná mezinárodní spolupráce v geologických vìdách. Zámìrem vydavatele bylo dodržet koncepci a pøitom pøíliš neomezovat autory a netrvat na dodržování osnovy. Takový pøístup má samozøejmì své výhody i nevýhody. Již se objevily názory, že nìkteré rozsáhlejší paleontologické práce pøíliš neodpovídají pùvodnímu zámìru. Odvážíme se též kritizovat, že nìkteré historické poznámky mají až pøíliš místní význam. Vìtšina prací však ètenáøe potìší. Pamìtníkù ubývá, dokumenty ze starého Rakouska-Uherskajsou vzácnìjší a vzácnìjší. Dík patøí našim rakouským pøátelùm nejen za vydání sborníku, ale i za peèlivé archivování a zpracovávání historických materiálù, ve kterých najdeme mnoho údajù o zemích koruny Ceské i o pøírodovìdcích, kteøí mìli zásluhu na jejich geologickém prozkoumání. Zdenìk Kukal 32