Wyniki wyszukiwania - BazTech

1

The margins of the Early Jurassic Trento Platform (Southern Alps)

Riva Alberto, Gianolla Piero, Caggiati Marcello

Geotourism / Geoturystyka

|

2023

|

nr 1-2 (72-73)

59--59

EN

Examples of Lower Jurassic carbonate platform margins are rare, probably due to the scarcity of good outcrops. One of the major palaeogeographic units of the Mesozoic Tethys, the Trento Platform, however, shows two different margin types facing the Belluno and the Lombardian basins. While the western margin, facing the Lombardian Basin, is showing an ooidal unit with frequent mud mounds (Massone Oolite), the eastern margin was poorly characterized, mainly due to difficult stratigraphic definition and problematic accessibility of outcrops. The eastern platform margin characteristics are strictly controlled by tectonic activity and the type of carbonate factory; the differences between the eastern and the western margin could be linked to windward-leeward position of the platform margin, more protected to the west than to the east. Subsidence increased since Late Triassic, due to the opening of the Alpine Tethys, defining shallow water areas, dominated by subtidal and peritidal muddy carbonates, and deeper basins, such as the Belluno and Lombardian Basin. More than 500 m of mud-dominated carbonates developed until Early Sinemurian, when major switch in the carbonate factory occurred. The Hettangian-Early Sinemurian margin is usually not well exposed and is strongly dolomitized and appears to be a tectonically controlled escarpments. Since Late Early Sinemurian, the carbonate factory changed and led to a huge production of peloids and ooids, promptly shed in the surrounding basin: in the Eastern Trento Platform we recognize a 400/500 m thick wedge of Sinemurian to Pliensbachian ooidal calcarenites pinching-out towards the basin, with scattered bioconstructions made of calcareous sponges across the margin. This wedge pinches out also towards the platform interior, showing that the ooids were poorly preserved on the platform top. The preserved slope shows an angle of about 20-25°. In the western margin, the resedimented ooids are more limited, probably due to the limited size of the marginal carbonate factory. In the Late Pliensbachian, probably in the Margaritatus zone, a drowning phase affected part of the eastern carbonate platform, switching to encrinitic calcarenites, while in the western one carbonate production continued until Bajocian. These encrinites are extremely thin on the platform top, but a resedimented wedge in the proximal basin highlights the position of the topographic margin. The margins of the Trento Platform is a rare example of Early Jurassic carbonate platform margin that can be used as a reference for coeval carbonate platform depositional systems.

2

Ammonite assemblage and age of the hydrocarbon seep La Elina, Neuquén Basin, Argentina

Parent Horacio, Kaim Andrzej, Garrido Alberto C.

Annales Societatis Geologorum Poloniae

|

2023

|

Vol. 93, No. 4

353--361

EN

The ancient hydrocarbon seep deposits at the La Elina Ranch, Neuquén Basin, northern Patagonia, Argentina, are the only Mesozoic seep site in South America yielding metazoan fossils. Apart from benthic mollusc shells and worm tubes, they yielded a number of nektonic ammonoids. Four species of ammonoids were identified: Hildaitoides retrocostatus, Hammatoceras ex gr. insigne, Calliphylloceras cf. nilssoni, and Phylloceras sp. The occurrences of three species (H. ex gr. insigne, C. cf. nilssoni, and Phylloceras sp.) probably are fortuitous, while H. retrocostatus might have actually thrived in, or around the seep, as indicated by numerous well-preserved juveniles, in addition to some adult specimens. The bathymetric estimates indicate a depth not greater than 200 m, while the benthic molluscs, typical of hydrocarbon seeps, indicate a much greater depth. It is hypothesized that the deep-water taxa might have occurred in a shallower setting, owing to rising anoxia and/or strong input of continental waters from the eastern and/or southeastern deltaic system. The ammonite assemblage indicates that the seep at La Elina is (Andean) Middle Toarcian, probably Chilensis Zone, in age.

3

Palaeolatitudinal gradients along the southeastern Palaeo-Pacific margin and the distribution of Early Jurassic bivalves

Damborenea S. E., Echevarria J.

Volumina Jurassica

|

2015

|

Vol. 13, no. 1

3--16

EN

Presence-absence bivalve species data for each Early Jurassic stage along southeastern South America between 20 and 46°S present-day latitude were processed by a set of analytical methods to analyse the palaeolatitudinal patterns of diversity and distribution. The expected decrease in species diversity towards higher latitudes is punctuated by a consistent local diversity increase between 34 and 42°, especially evident during Pliensbachian and Toarcian times, which may be due to an abrupt change in palaeogeography at that latitude, coinciding with the Curicó direct connection to the open ocean and the establishment of an increased variety of habitats within the extensive Neuquén Basin. The proportions of systematic groups show relative increases towards both higher latitudes (Crassatelloidea, Nuculanoidea, Pectinoidea, Monotoidea, Inoceramoidea) and lower latitudes (Trigonioidea, Pholadomyoidea, Limoidea, Lucinoidea). Epifaunal bivalves were dominant during the Hettangian but by Pliensbachian–Toarcian times they were less common than infaunal ones, while semi-infaunal species had low diversities during the whole Early Jurassic. This study suggests that (a) large scale geographical conditions should be taken into account for the analysis of latitudinal diversity trends among benthonic faunas; and (b) latitudinal trends of some living bivalve lineages may have a longer and more complex history than previously thought.

4

Profil sedymentologiczny przedkelowejskich (jurajskich) utworów silikoklastycznych w otworze badawczym Cianowice 2 (okolice Krakowa)

Pieńkowski G.

Biuletyn Państwowego Instytutu Geologicznego

|

2014

|

nr 459

147--156

PL

W otworze Cianowice 2 (okolice Krakowa), bezpośrednio na niezgodności erozyjnej ze zmetamorfizowanymi łupkami neoproterozoiku (ediakaru), a pod węglanowymi utworami jury środkowej (keloweju), występuje ponad 20-metrowy kompleks utworów silikoklastycznych (brekcje, zlepieńce, piaskowce, mułowce z podrzędnymi wkładkami węgli, syderytów i margli). Wykonane w czterech próbkach analizy palinologiczne pozwoliły uzyskać stosunkowo ubogi zespół miosporowy o szerokim zasięgu stratygraficznym, niedający rozstrzygających rezultatów, potwierdzający bardzo ogólnie jedynie jurajski wiek utworów (Jadwiga Ziaja, inf. ustna). Pozycja stratygraficzna tych utworów nie jest jasna – mogą one należeć zarówno do wczesnej jury, do środkowej jury, jak i obu tych epok, a najniższe warstwy grubookruchowe mogą być jeszcze starsze i reprezentować późny trias. Cały nawiercony kompleks silikoklastyczny został podzielony na pięć wyraźnych sukcesji. W poszczególnych sukcesjach dominują podrzędne cykle proste o ziarnie (i energii przepływu) malejący ku górze. Sukcesja 1 składa się z brekcji i zlepieńców o nieuporządkowanej strukturze, co wskazuje na spływy mułowe (soliflukcyjne), przechodzące być może w spływy wodne w środowisku stożków aluwialnych. Sukcesja 2 składa się z pięciu cykli prostych piaszczysto-mułowcowych, ze śladami wegetacji roślinnej, utworzonych na równi rzecznej. Sukcesja 3 składa się w całości z mułowców o genezie jeziorno-bagiennej, z licznymi śladami wegetacji roślinnej i węglami w stropie. Sukcesje 4 i 5 to ponownie sukcesje złożone z cykli prostych o genezie rzecznej. Cały profil badanych utworów silikoklastycznych wykazuje peneplenizację żywej początkowo rzeźby obszarów źródłowych i ciągły spadek energii procesów depozycyjnych ku górze aż do stropu sukcesji 3 z węglami, a następnie ponowny nawrót równi rzecznej. Poszczególne sukcesje są oddzielone powierzchniami nieciągłości (przeważnie erozyjnymi, jedynie spąg sukcesji 3 ma charakter odpowiednika powierzchni mogącej być korelatywną powierzchnią transgresji), które mogą stanowić regionalne powierzchnie korelacyjne (zwłaszcza dolne granice sukcesji 1, 3 i 5). Sukcesje o dolnych granicach erozyjnych mogą odpowiadać sekwencjom depozycyjnym. Porównania regionalne otworu wiertniczego Cianowice 2 z otworem Parkoszowice 58 BN położonym ok. 40 km na północny zachód skłaniają do uznania tych utworów wstępnie za jurę dolną (najprawdopodobniej pliensbach–toark), grubookruchowe utwory sukcesji 1 w spągu otworu mogą reprezentować także wiek późnotriasowy. Do czasu uzyskania bardziej precyzyjnych danych biostratygraficznych lub chemostratygraficznych nie można potwierdzić tego z całą pewnością ponad stwierdzenie, że są to utwory jurajskie starsze od keloweju.

EN

In the Cianowice 2 borehole (located in the vicinity of Kraków), straight on the erosional unconformity on the top of metamorphosed Neo-Proterozoic (Ediacaran) shales and below carbonate deposits of Callovian, 20 meters thick interval of siliciclastic rocks has been encountered. The siliciclastic rocks are composed of conglomerates, sandstones, mudstones and subordinate intercalations of coal, siderite and marls. Stratigraphical position of this interval can be inferred based on poorly-preserved miospore assemblage, spanning relatively long geological time (Jadwiga Ziaja, pers. comm.) – it can represent either Early or Middle Jurassic, or both of those epochs, while the lowermost coarse-grained package can be even of an older, i.e. Triassic age. The interval was subdivided into 5 well-distinguished sedimentary successions, separated by bounding surfaces, mostly of erosional character – only succession 3 starts with sharp lithological contrast between sandy deposits and overlying mudstones, which reflects flooding and rapid retrogradation (either lacustrine or lagoonal). All these bounding surfaces (particularly bottoms of successions 1, 3 and 5) are of regional correlative significance-erosional bounding surfaces can represent sequence boundaries, while bottom of the succession 3 can represent correlative surface of a transgression. In each succession, except for the lowermost one, subordinate fining-upward cycles are dominating. They represent diminishing-upward energy of transport. The succession 1 is composed of breccia and conglomerates with chaotic structure, indicative of mudflow – dominated fans, possibly passing into alluvial fans and back to the mudflow fan again in the top. There is a marked lithological contrast (possibly connected also with considerable hiatus) between the coarse-grained deposits of succession 1 and following successions built of fine-grained sandstones, siltstones, mudstones and claystones. The succession 2 is composed of five fining-upward cycles, indicative of fluvial environment (fluvial plain), with traces of plant vegetation. The succession 3 is entirely composed of mudstones of lacustrine origin, with numerous traces of plant vegetation, siderite concretions and bands and coals at the top. Successions 4 i 5 again contain typical fining-upward fluvial cycles with traces of plant vegetation. The overall profile shows peneplanation of a landscape and continuous diminishing of energy of sedimentary processes up to the top of succession 3 marked with coals. Then, fluvial sedimentation returned. Regional comparison of the Cianowice 2 borehole with borehole Parkoszowice 58 BN, located some 40 km to NW tends to suggest the Early Jurassic (most probably Pliensbachian–Toarcian) age of the profile (the lowermost coarse-grained part can be of a Triassic age), but until more reliable biostratigraphical or chemostratigraphical evidences are obtained, these more detailed interpretations of stratigraphical division remain tentative.

5

Tropy dinozaurów z wczesnojurajskiego ekosystemu z Sołtykowa w Górach Świętokrzyskich

Niedźwiedzki G.

Biuletyn Państwowego Instytutu Geologicznego

|

2011

|

nr 447

49--98

PL

W artykule została przedstawiona rekonstrukcja wczesnojurajskiego zespołu dinozaurów (sprzed około 200 milionów lat) na podstawie danych paleoichnologicznych (skamieniałości śladowych – tropów dinozaurów). W latach 1997–2009 autor zebrał ze stanowiska w Sołtykowie materiał badawczy liczący kilkadziesiąt okazów, wykonał również szereg dokumentacji fotograficznych oraz replik gipsowych (odlewów) z okazów pozostawionych w terenie. Ten materiał to tropy dinozaurów drapieżnych – teropodów oraz roślinożernych zauropodomorfów i wczesnych dinozaurów ptasiomiednicznych. Artykuł zawiera również charakterystykę środowiska abiotycznego oraz innych znalezisk paleontologicznych i paleoichnologicznych (skamieniałości śladowe bezkręgowców). Odsłonięcie Sołtyków reprezentuje unikatowy zapis wczesnojurajskiego ekosystemu lądowego, związanego z rozwojem rzeki anastomozująco-meandrującej oraz przyległych do niej obszarów równi zalewowej. Stanowisko to dostarcza danych paleoichnologicznych użytecznych do określenia różnorodności biologicznej, stanu ewolucyjnego i biologii wczesnych dinozaurów oraz innych ówczesnych kręgowców lądowych (gadów ssakokształtnych wczesnych ssaków, lepidozaurów, pterozaurów i wczesnych krokodylomorfów).

EN

This paper presents reconstruction of the Early Jurassic dinosaurs assemblage (about 200 million years old) based on paleoichnological data (trace fossils – tracks of dinosaurs). In 1997–2009, the author collected paleontological material counting several tens of specimens from the Sołtyków clay-pit and made photographic documentation in the site, as well as replica plaster (casts) from specimens left in the field. This material contains predatory dinosaur tracks and tracks of herbivorous sauropodomorphs and early ornithischia. This publication also includes description of the abiotic environment and other paleontological finds (e.g., insects, bivalves fossils) and paleoichnological finds (invertebrate trace fossils). The Early Jurassic deposits from Sołtyków represent a unique record of an ecosystem of in-land environment connected with the development of an anastomosing-meandering river and adjacent flood plains. This locality provides paleoichnological data valuable for determining biodiversity, evolutionary position and biology of the early dinosaurs and other terrestrial vertebrates (mammal-like reptiles, early mammals, lepidosaurs, pterosaurs and early crocodylomorphs).

6

Taxonomy and palaeoecology of the Early Jurassic macroflora from Odrowąż, central Poland

Barbacka M., Ziaja J., Wcisło-Luraniec E.

Acta Geologica Polonica

|

2010

|

Vol. 60, no. 3

373-392

EN

The locality of Odrowąż is an Early Jurassic section in central Poland, with a taxonomically relatively poor flora. The available material is composed of both macro- and microremains. The macroremains, represented by 720 specimens (491 suitable for study), consist mainly of leaves, shoots, rhizomes, as well as male and female cones and fragments of other fructifications. sphenophytes, pteridophytes, pteridosperms, bennettites, cycads, ginkgophytes, conifers are represented by single taxa, only ferns are more diverse. The material is dominated by the conifer Hirmeriella muensteri (schenk) Jung and the benettite Pterophyllum alinae Barbacka sp. nov. Taxonomically, the ferns are the most diverse group (five species belonging to five genera). Most of the plants show adaptations to wet conditions, which corresponds well to the proposed sedimentary environment, a river plain. The complete material shows, however, that the floral remains originated from a wider area situated along the river and on its banks. One new genus, Odrolepis, three new species, Odrolepis liassica, Pterophyllum alinae, Paracycas minuta, and one new forma, Todites princeps, forma trilobata, are described. some forms are left in open nomenclature.

7

The Upper Sinemurian ammonite succession in the Sierra Madre Oriental (Mexico)

Meister Ch., Blau J., Dommergues J-L., Schlatter R., Schmidt-Effing R.

Volumina Jurassica

|

2009

|

Vol. 7, no. 1

31-36

EN

In the Sierra Madre Oriental (Mexico), the biostratigraphic subdivision of the Upper Sinemurian can be refined. It has been possible to differentiate 11 horizons from the upper Obtusum Zone to the top of the Raricostatum Zone which are correlated with the NW European standard zonation. The index species of each horizon is figured.

8

Sinemurian to lowermost Toarcian ammonites of the Brescian Prealps (Southern Alps, Italy): preliminary biostratigraphical framework and correlations

Meister Ch., Schirolli P., Dommergues J-L.

Volumina Jurassica

|

2009

|

Vol. 7, no. 1

9-18

EN

A set of 28 ammonite biohorizons or faunal assemblages is proposed for the Sinemurian, the Pliensbachian and the lowermost Toarcian of the Brescian Prealps, in part based on the published data of the authors of this contribution and partly on new results, derived both from recent field investigations and from the study of the historical collection of Lower Jurassic ammonites preserved in the Museum of Natural Sciences of Brescia (Northern Italy). The biohorizons are present in the Liassic carbonate succession of the Brescian Prealps, cropping out between the eastern surroundings of Brescia (Botticino), to the east, and Lake Iseo, to the west. Since the Hettangian this region was subjected to Jurassic rifting. The area of study was located on the eastern border of the wide Lombardian Basin, a part of the southern continental passive margin of Tethys. An articulated fault-system, trending from Brescia to the North, separated the western subsiding area of the Val Trompia-Sebino Basin from the eastern Botticino structural high. After the drowning of the Rhetian-Hettangian Corna Platform, the very thick synrift succession of the Medolo Group accumulated in the Val Trompia-Sebino Basin, whereas the coeval reduced sequence of the Rezzato Encrinite and the overlying Botticino Corso Rosso covered the Botticino High, subsequent to the Early Sinemurian. The ammonite biohorizons and assemblages recognised are quite well integrated and correlable with either the NW European standard zonation or the different zonations proposed for the Tethyan Realm.

9

Paleogeografia południowo-wschodniej Azji i jej związek z rozmieszczeniem wczesnojurajskich budowli małżowych (z grupy Lithiotis) na tle wielkiego wymierania trias/jura

Krobicki M., Golonka J.

Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

|

2009

|

T. 35, z. 3/1

79-90

EN

The separation of Laurasia and Gondwana, which was initiated by the Triassic break-up of Pangea, continued during Early-Middle Jurassic times. The origin of the narrow sea strait. so-called "Hispanic Corridor", took place between these two continents and connection of the Panthalassa Ocean (Proto-Pacific) and western (Alpine) Tethys gradually started in Early Jurassic, most probably in Sinemurian-Pliensbachian times. Recovery of marine fauna after Triassic/Jurassic mass extinction event was mainly marked by world-wide distribution of Lithiotis-type bivalve buildups. They indicate mainly shallow-marine/lagoon-type carbonate sedimentation and palaeogeographic/geodynamic regimes during break-up of Pangea in Pliensbachian-Early Toarcian times.

10

Sinemurian to lowermost Toarcian ammonites of the Brescian Alps (Southern Alps, Italy): biostratigraphical framework and correlations

Meister Ch., Schirolli P., Dommergues J-L.

Volumina Jurassica

|

2006

|

Vol. 4, no. 1

184-185

EN

A set of 28 ammonite biohorizons or faunal assemblages can be proposed for the Sinemurian, the Pliensbachian and the lowermost Toarcian in the Brescian Alps, in part based on the data from Dommergues et al. (1997) and partly on new results, deriving both from recent field investigations and from the study of the historical collection of the Lower Jurassic ammonites preserved in the Museum of Natural Sciences of Brescia (Northern Italy), placed into their stratigraphical framework (Fig. 1). The biohorizons are referred to the Liassic carbonate succession of the Brescian Alps, outcropping between the eastern surroundings of Brescia (Botticino), to the East, and the Lake Iseo, to the West. Since the Hettangian the region was subjected to the paroxismal phase of the Jurassic rifting and the area of study was located in the eastern border of the wide Lombardian Basin, a part of the southern continental passive margin of the Tethys. At the beginning of Jurassic, an articulated fault-system, composed of N-S master faults (W-dipping) and W-E transfer faults, located from Brescia to the North, separated a western growing basinal area from the eastern Botticino structural high. Since Hettangian to the onset of Toarcian, almost 1000 m of well-stratified cherty marly limestones of the Medolo Group (Gardone Val Trompia Limestone and Domaro Limestone formations) represent the synrift deposition of the Sebino Basin, following the drowning of the Raethian-Hettangian Corna Platform. In contrast, after the Early Sinemurian a coeval reduced sequence (50 m thick), composed by the Rezzato Encrinite (Lower Sinemurian to Upper Carixian) and the overlying thinly-bedded and nodular ammonitic marly limestones of the Botticino Corso Rosso (Upper Carixian and Domerian), covered the Corna Platform in the Botticino High. The recognized ammonite biohorizons and assemblages are quite well integrated and correlable with either the NW European standard zonation or the different zonations given for the Tethyan realm (Appennines, Subbeticas and Austrian and Hungarian Upper Austroalpine). Most of these stratigraphical units are based on Tethyan taxa. Only two horizons (U. cf. jamesoni horizon and P. solare horizon) show NW European affinites. Moreover the E. quenstedti horizon is only known from the northern margin of the Tethys, mainly from the Upper Austroalpine units.

11

Sinemurian ammonite succession from the Sierra Madre Oriental (Mexico)

Blau J., Meister Ch., Dommergues J-L., Schlatter R., Schmidt-Effing R.

Volumina Jurassica

|

2006

|

Vol. 4, no. 1

147-148

EN

In a series of studies (Blau et al. 2001, 2002, 2003; Meister et al. 2002, 2005) dedicated to Liassic (Sinemurian) ammonites of the Sierra Madre Oriental (Mexico), we have described 42 taxa, amongst them one new genus and five new species. After a critical analysis of Erben’s collection and with our own collections, we propose a synthetic succession of 13 correlable units “biohorizons”. Even though the Sinemurian sediments of the Huayacocotla Basin are very thick only two periods are well represented: the Bucklandi and Semicostatum zones for the Lower Sinemurian and the upper Obtusum and Raricostatum zones for the Upper Sinemurian. These two time intervals can be well correlated with South and North American biostratigraphic schemes. The Lower Sinemurian is characterized by the acme of Arnioceras a genus well distributed on the eastern Panthalassian rim. The Upper Sinemurian allows a much more refined biostratigraphic subdivision and more acute correlations. In the upper Obtusum Zone Euerbenites is an index fossil and can be correlated from Sonora to Peru. In the Raricostatum Zone several horizons allow acute correlation with South America (O. incaguasiense and P. tardecrescens horizons) and with North America (P. harbledownense and P. rothpletzi horizons). Mainly in the Upper Sinemurian there is quite strong endemism of the ammonite fauna in the Huayacocotla Basin (nearly 40%) which may be due to a quite isolated palaeogeographical position of the basin. On the other hand the affinities to Tethyan faunas are obvious. There is little palaeontologic evidence for a Sinemurian connection between Eastern Pacific (Panthalassa) and Western Tethys through the Hispanic Corridor. First palaeontological evidence indicates a possible connection not before the Pliensbachian. If this connection was not established in the Sinemurian, we must imagine other migration ways to explain the Tethyan affinities. There are at least four possibilities or combinations of migration routes: southern peri-Pangean, peri-Asiatic, latudinal trans-Panthalassian, and Boreal (Viking Corridor, Arctic seas). All these migration routes remain hypothetical and the establishment of the Hispanic Corridor already in the Sinemurian cannot be ruled out completely.

12

Petrological studies of the Early Jurassic siderites from Western Pomerania (Poland)

Maliszewska A., Kozłowska A., Kuberska M.

Volumina Jurassica

|

2006

|

Vol. 4, no. 1

96-97

EN

Petrological studies of siderite layers and concretions occurring in the Early Jurassic periodically marine deposits, described as the brackish shelf facies (Feldman-Olszewska 1997), were conducted. The analyzed rocks are mainly built of the sideroplesite, while siderite and pistomesite occur sporadically. Two generations of the sideroplesite were distinguished, that essentially differ due to the size of the rhombohedra. The older generation forms micritic concretions and micritic layers of the clayey siderites. The younger generation either represents a groundmass of the sparry siderites or cements of the sideritic sandstones. Some layers of siderites contain ooids and aggregates of the chamosite and phosphates, chamosite intraclasts, pyrite, detrital quartz and micas. Numerous shells of foraminifers and occasionally molluscs are present, too. Nine samples of the clayish siderites from the Mechowo IG1 borehole were isotopically analyzed aiming at oxygen and carbon ratios. The recognition of δ18 O of crystallization waters responsible for the siderite formation was the final aim of the studies. A formula given by Carothers et al. (1998) as well as the results of studies on the siderites of Baker et al. (1995) were applied. It results from the calculations that the δ18 O of the crystallization water oscillated between -12 and -3‰ SMOW in the Late Sinemurian, while in the Early Pliensbachian and the Early Toarcian it changed from -10 to +2‰ SMOW. That points to the meteoric waters gradually enriched in the 18 O isotope. The δ13C values in the siderite samples oscillate from -0.85 to -10.57‰ PDB. That suggests that the pore waters were enriched in carbon formed in the microbiological zone of the metanogenesis due to the alteration of the organic matter (Longstaffe & Ayalon 1997). The whole petrological analysis of the siderites points to their origin as the product of the diagenetic processes which operated in the bottom mud of the shallow brackish basins in the anoxic conditions with the influence of the meteoritic waters.

13

Oyster and brachiopod stable isotopes across the Triassic/Jurassic boundary and in the Early Jurassic

Korte C., Hesselbo S., Jenkyns H., Dietl G., Dulai A., Vörös A.

Volumina Jurassica

|

2006

|

Vol. 4, no. 1

289-289

EN

Oxygen and carbon isotope values have been obtained from oysters for the Triassic/Jurassic boundary section at Lavernock Point (Wales), and from brachiopods and oysters for different Hettangian, Sinemurian and Pliensbachian localities of South Germany and Hungary. Low-Mg-calcite brachiopods and oysters are particularly suitable for such studies because this carbonate phase is the most resistant to diagenetic alteration. Nevertheless, all fossils have been screened by chemical and optical techniques (optical microscope, scanning electron microscopy, trace element analyses) to evaluate the isotope data for diagenetic change, and only samples with Mn content less than 250 ppm and Sr content more than 400 ppm, complemented by well preserved textures under SEM, were considered in this study. For the Triassic/Jurassic boundary (TJB) the carbon isotope values are at about 2.5‰ in the lower Langport Member, increase to 4.5‰ in the lowest Blue Lias and decrease subsequently to 1.5‰ just below the Planorbis Zone. The data remain low with variations between 1.5 and 2.5‰ up to the Liassicus Zone. These results correspond to the organic carbon isotope trend for the Triassic/Jurassic boundary section at St Audrie's Bay (Hesselbo et al. 2002). Oxygen isotope values increase from -0.5‰ in lower Langport Member to 0‰ at the base of the Blue Lias, decrease in the Blue Lias down to -1.5‰ just below the Planorbis Zone and change in parallel with the organic and inorganic carbon-isotope trends. The δ ¹ ⁸O values indicate decreasing seawater temperature with increasing δ ¹ ³C in the Langport Member and increasing water temperatures of about 6°C in the lower Blue Lias. The distinct warming trend occurred during the "main" TJB negative excursion. Carbon and oxygen isotope values from Hettangian, Sinemurian and Pliensbachian brachiopods and oysters, as well as from some complementary belemnites, show similar values and trends compared to the data compilation by Jenkyns et al. (2002). Carbon isotope values are between 1 and 2‰ in the Hettangian and Early Sinemurian followed by an increase of about 1‰ during the Sinemurian, a nearly 3‰ decrease in the Early Pliensbachian and higher δ ¹ ³C values (˜2.5‰) in the later Pliensbachian.

14

Onset of erg sedimentation during the Early Jurassic on the Colorado Plateau, southwestern U.S.A.: climatic, eustatic and tectonic controls

Tanner L., Lucas S.

Volumina Jurassica

|

2006

|

Vol. 4, no. 1

106-106

EN

Deposition of the Moenave and Wingate formations took place during the latest Triassic to Early Jurassic in a mosaic of terrestrial subenvironments including fluvial, lacustrine, and eolian. Fluvial-lacustrine processes dominated Moenave deposition, which included channelized flow in ephemeral to perennial streams, unconfined flow (sheetwash) in interchannel areas, ephemeral lakes (playas), and perennial lakes that were subject to episodic desiccation. The Moenave terminal floodplain, which was dotted by broad, shallow lakes, interfingered with the Wingate erg, where eolian processes dominated. The Moenave-Wingate outcrop belt exposes a north-south lithofacies gradient from distal (erg margin) to proximal (erg interior) as dominantly fluvial-lacustrine lithofacies in the north are replaced by mainly eolian dune and interdune deposits to the south, recording encroachment of the Wingate erg. The prevalence of ephemeral stream and eolian environments during deposition of these strata indicates a seasonally arid climate during the latest Triassic to earliest Jurassic. We see no sedimentologic evidence for significant climate change at the Triassic/Jurassic boundary, or at any time encompassed by this sedimentary succession. The growth and incursion of the Wingate erg into the Moenave fluvial system may have been driven by the availability of sediment in the up-wind source area, the coastal plain and coastline to which the Moenave streams delivered sediment. We interpret a eustatic signal as responsible for formation of this erg as long-term regression during the Rhaetian and continued Hettangian low-stand exposed a broader area of shallow marine sediments to eolian reworking. Preservation of the erg deposits may have been enhanced by tectonically controlled accommodation space as continental shortening led to crustal flexure during the Early Jurassic.

15

Lower Jurassic carbonate platform-to-basin transition at Mt. Rumija (Montenegro)

Crne A., Gorican S., Cadjenovic D.

Volumina Jurassica

|

2006

|

Vol. 4, no. 1

82-83

EN

Mount Rumija, Montenegro represents one of the best-preserved Lower Jurassic platform-to-basin transitions in the Dinarides. Mt. Rumija is located in the High Karst Zone, overthrust on the Budva Zone. In the Mesozoic the High Karst Zone was a part of the Adriatic-Dinaric Carbonate Platform (ADCP), whereas the Budva Zone was a deeper basin. We describe two complete Lower Jurassic sections (Tejani and Livari) and a complementary Pliensbachian-Toarcian section (Seoce). The successions exhibit great facies differences across short distances and provide important new data for the reconstruction of the Lower Jurassic platform-to-basin system. At Tejani and Livari, the Upper Triassic Dachstein Limestone is overlain by micritic limestone, which begins with a few beds of fine- to medium-grained calcarenites. At Tejani, 100 m of thick-bedded coarse-grained oolitic limestone follow, at places displaying cross-stratification. Laterally, at Livari, the correlative succession is 180 m thick and consists of three calcareous turbididite packages. The first and the third package are lithologically identical: fine- to medium-grained calcarenites, which contain 50% replacement chert layers and nodules; the calcarenites contain pellets, echinoderm fragments, foraminifers, ooids and sponge spicules. The second package is an oolitic limestone that lacks chert. The overlying lithostratigraphic unit is common to both sections and aids in correlation. It consists of a 30 m thick succession of marly limestone and marl overlain by 30 m of medium-bedded bioclastic limestone. The marly limestone contains foraminifers, ostracodes, sponge spicules and rare radiolarians, while the bioclastic limestone contains abundant brachiopod shells, echinoderm fragments and several Fe-Mn crusts. The bioclastic limestone is overlain by oolitic limestone. The base of the Seoce section starts with a thick-bedded Lithiotis limestone. A nodular micritic limestone follows, containing mostly pellets and rare bioclasts - fragments of echinoderms, ostracodes and brachiopods. The succession ends with oolitic limestone. In the Budva Basin, the Upper Triassic Halobia limestone (pelagic lime mudstone with replacement chert) is overlain by Passée Jaspeuse (bedded calcareous chert). The overlying Bar Limestone (calcareous turbidites) was deposited beginning in the Late Sinemurian - Early(?) Pliensbachian. It is composed of Lower and Upper Member, divided by a marly horizon, probably Toarcian in age. The lateral transition from the lagoonal environment (Seoce) to the platform edge (Tejani) and deeper water environment (Livari) can be observed at Mt. Rumija. Vertically, two abrupt facies changes occur. The first one is the beginning of the micritic limestone sedimentation above the Dachstein limestone. The second change is observed both in the shallow-water environment (nodular limestone overlying Lithiotis limestone) and on the platform-to-basin transition (sedimentation of marly limestone with open-marine biota). Two abrupt facies changes on the carbonate platform are correlated to facies changes in the Budva Basin (Halobia limestone - Passee Jaspeuse, Lower Bar Limestone Member - marl, respectively). The facies changes correspond to two drowning events: at T/J boundary and at Late Pliensbachian - Upper Toarcian.

16

Zagadkowa roślina z wczesnej jury Gór Świętokrzyskich

Gierliński G.D., Ploch I., Sabath K., Ziaja J.

Przegląd Geologiczny

|

2006

|

Vol. 54, nr 2

139-141

EN

Fossils plants (less than 0.5 m high) preserved in upright position were found in Śmiłów Quarry (E of Szydłowiec) at the northern slope of the Holy Cross Mountains. The plants were preserved as impressions of ascending narrow-leafed stems in fine-grained sandstone of the Drzewica Formation (upper Pliensbachian). The leaves are 5-25 cm long and about 2-5 mm wide; the angle between them and the short main axis ranges within 20-30o. Morphology of the plant resembles schizeacean ferns, but also that of Aethophyllum stipulare Brongniart 1828 from Anisian of France, recognized by Grauvogel-Stamm (1978) as an herbaceous gymnosperm. Grauvogel-Stamm (1978) supposed that the leaves Podozamites and cone scales Swedenborgia, common in Jurassic strata of higher palaeolatitudes, are derived from descendants of Aethophyllum. Podozamites leaves often occur in many dinosaur track-bearing horizons in the Polish Jurassic. Thus, herbaceous conifers might have played an important and often underestimated role in the Mesozoic ecosystems (possibly as a substantial part of dinosaur diet). The possiblity of coniferous equivalents of Cenophytic herbaceous angiosperms, as well as a possibility of their coevolution with Mesozoic low browsing and grazing herbivore megafauna is worth further palaeobotanical and palaeoecological studies.

17

Ślady wielkich teropodów z wczesnojurajskich osadów Gór Świętokrzyskich

Niedźwiedzki G.

Przegląd Geologiczny

|

2006

|

Vol. 54, nr 7

615-621

EN

Numerous gigantic and large theropod dinosaur footprints were recently discovered in the Lower Jurassic deposits of the Holy Cross Mountains (central Poland). These finds provide paleoichnological evidence for the occurrence of gigantic predatory dinosaurs in the earliest Jurassic (Hettangian) times. The gigantic and large theropod tracks came from two well-known lower Hettangian tracksites at Sołtykow and Gromadzice. The Sołtyków outcrop represents a siliciclastic coal-bearing lithofacies association of a fairly well-watered alluvial plain. The sequence from the Gromadzice site is dominated by typical meandering river deposits with lenticular, incised channels and overbank mudstones, rich in drifted flora and plant roots. Hitherto, twenty four specimens of gigantic theropod Eubrontes-like footprints (50–65 cm long) were found at Sołtyków tracksite. Another large theropod footprints (30–45 cm) identified at Sołtyków, resemble Kayentapus-like ichnites and classic ichnotaxa of the Newark Supergroup (i.e., Eubrontes giganteus Hitchcock, 1845 sensu Olsen et al., 1998). In the Gromadzice site, large Eubrontes giganteus, Eubrontes sp., and cf. Eubrontes sp. footprints were identified. The intriguing gigantic ichnites from Sołtyków are more similar to the large prints left by Middle–Late Jurassic theropods than to other finds from the Early Jurassic.

18

New saurischian dinosaur footprints from the Lower Jurassic of Poland

Gierliński G., Niedźwiedzki G.

Geological Quarterly

|

2005

|

Vol. 49, No. 1

99--104

EN

New Early Jurassic material of saurischian dinosaur footprints has been found in the coastal siliciclastic deposits of the Holy Cross Mountains. Seven specimens ofmedium-sized footprints, assigned to Anchisauripus sp., are reported fromthe upper Hettangian deposits at the Zapniów clay pit. Other finds of small-sized theropod footprints, identified as Grallator sp., were discovered in a new tracksite at the Śmiłów quarry, where the tracks are reported for the first time in the Polish Pliensbachian. Large theropod footprints of Kayentapus were first found at the upper Gromadzice site (deltaic deposits), and in Gliniany Las (barrier-lagoonal deposits), while the first Polish find of Otozoum came from the lower Gromadzice site (delta plain deposits).

19

Sołtyków - unikalny zapis paleoekologiczny wczesnojurajskich utworów kontynentalnych

Pieńkowski G.

Volumina Jurassica

|

2004

|

Vol. 2, no. 1

1-16

EN

The Sołtyków exposure is an old, long time abandoned clay pit. This exposure became known as a classical outcrop of alluvial-lacustrine deposits. Floral remains point to the earliest Jurassic (Lias 1-2) age, and the sequence stratigraphic correlation allows to narrow its age range to the Early Hettangian (Planorbis biochronozone). Sołtyków exposure fits the avulsion-controlled (crevassing- anastomosing) fluvial sedimentation model, however, some features such as laterally-accreted bedding point also to presence of high-sinuosity/meandering streams. Relatively thick and individualised package of lacustrine deposits occurring in the Sołtyków outcrop points to some permanency of the lake/swamp area during deposition of the sediments visible in the outcrop. Palaeosols are both of Podzol and Histosol type. The plant fossils in the Sołtyków exposure are very abundant and well preserved. The list of plants includes Neocalamites, the matoniacean, osmundacean and other indeterminate ferns, as well as pteridosperms, benettitaleans and conifers. Non-marine trace fossils comprise Coprinisphaera, Scoyeniaand aquatic Mermia ichnofacies. Other fossils that occur in Sołtyko?w are represented by Unionidae freshwater bivalve assemblage, insect remains, fresh-water ostracodes and scales of palaeoniscid fish. The Sołtyków exposure is well known Early Jurassic tracksite with numerous dinosaur footprints, mainly left by theropods and sauropods, and early mammalian footprints. The dinosaur nesting ground was also described. Recently, the Sołtyków exposure has been declared a natural reserve. Nature conservation problems are discussed. Due to many unique finds in Sołtyków (the oldest known evidence of gregarious ethology of dinosaurs, the biggest known Early Jurassic theropod footprints, rich and well-preserved invertebrate ichnoforms and plant remains, this exposure should be enlisted on the UNESCO World Heritage List (in geological cathegory). Moreover, the idea of “Kamienna Valley” geopark, comprising Sołtyków and other valuable outcrops in the region, is introduced.

20

Nowe znaleziska tropów dinozaurów ze śladem śródstopia z dolnej jury Gór Świętokrzyskich

Niedźwiedzki G., Niedźwiedzki D.

Przegląd Geologiczny

|

2004

|

Vol. 52, nr 3

237-242

EN

Numerous specimens of dinosaur footprints with metatarsal impressions were collected from the Early Jurassic deposits of the Holy Cross Mountains, Poland. These elongate theropod and ornithischian footprints came from the Hettangian sites of Sołtyków, Gromadzice, and Gliniany Las. The following dinosaur ichnogenera were identified among them: Anchisauripus Lull, 1904; Kayentapus Welles, 1971; Moyenisauropus Ellenberger, 1974; Anomoepus Hitchcock, 1848.