Ostracod biostratigraphy in the Lower Cretaceous of the Iberian chain (eastern Spain)

Lower Cretaceous ostracod associations (marine and nonmarine) have been studied from 34 sections of the Iberian chain or, geologically spoken, the Iberian basin (eastern Spain), in order to contribute to the chronostratigraphic correlation of the various predominantly nonmarine lithostratigraphic units in the Cameros, Maestrazgo, and South Iberian sub-basins (and the Central Iberian high in between). We have combined 87 ostracod species from 22 genera to 11 associations, each typical for certain stratigraphic levels (mostly stages) and ecologies. Nonmarine associations (dominated by the genera Cypridea and Theriosynoecum) prevailed from the Berriasian to the Barremian interval, whereas marine-brackish associations (much more diverse on the generic level) prevailed during the Aptian and Albian, and to a lesser extent during the Berriasian and Barremian. In most cases, our new ostracod data are consistent with previous correlative charts, as based upon other biostratigraphic data, mainly from charophytes, but also from few marine fossils in marine intercalations, and on depositional sequence stratigraphy. But in a few cases, our results are more or less different from those of established charts, namely in the eastern Cameros sub-basin (the Urbión group considered Late Berriasian in age instead of Valanginian-Barremian, and the Enciso group considered Late Valanginian-Barremian instead of Late Barremian-Aptian), in the northeastern Maestrazgo sub-basin (the Polacos Formation considered Late Berriasian-Early Hauterivian instead of Late Berriasian only), and in the uppermost part of the Lower Cretaceous in the South Iberian sub-basin (the Contreras and El Caroig Formations considered Albian instead of Aptian). Finally, we evaluate the usability of ostracod biostratigraphy in the Lower Cretaceous of eastern Spain and conclude that, if treated with great care especially under consideration of the biogeography and reproduction/dispersal strategies of the various groups, it should be given priority over pure lithostratigraphic correlations in conflicting cases.Las asociaciones de ostrácodos del Cretácico Inferior (marino y no marino) han sido estudiadas en 34 secciones de la cadena Ibérica, o en términos geológicos, la cuenca Ibérica (este de España) con el fin de contribuir a la correlación cronoestratigráfica de las variadas unidades, predominantemente no marinas, de las subcuencas de Cameros, Maestrazgo y Suribéricas (así como el alto Centroibérico intermedio). Hemos descrito 87 especies de ostrácodos pertenecientes a 22 géneros e incluidos en 11 asociaciones, cada una de ellas características de un determinado nivel estratigráfico (pisos sobre todo) y con una paleoecología concreta. Las asociaciones no marinas (dominadas por los géneros Cypridea y Theriosynoecum) prevalecieron desde el Berriasiense hasta el Barremiense, mientras que las asociaciones marinas-estuarinas (mucho más diversificadas a nivel genérico) se desarrollaron durante el Aptiense y Albiense, y en un grado menor, durante el Berriasiense y Barremiense. En la mayoría de los casos, nuestros nuevos datos de los ostrácodos son consistentes con los esquemas de correlación previos, basados en otros datos bioestratigráficos, sobre todo en charofitas, aunque también en los pocos fósiles presentes en las intercalaciones marinas, así como en la estratigrafía secuencial. Sin embargo, en algunos casos nuestros resultados son más o menos diferentes de los esquemas establecidos, sobre todo para la subcuenca oriental de Cameros (el Grupo Urbión es considerado de edad Valanginiense Superior-Barremiense, en lugar de Barremiense Superior-Aptiense), en la subcuenca nordoriental del Maestrazgo (la Formación Polacos es considerada Berriasiense Superior-Hauteriviense Inferior, en lugar de solo Berriasiense Superior) y en la parte superior del Cretácico Inferior en la subcuenca Suribérica (las Formaciones Contreras y El Caroig son consideradas del Albiense en lugar del Aptiense). Finalmente evaluamos la utilidad de la bioestratigrafía basada en los ostrácodos en el Cretácico Inferior del este de España y concluimos en que, si se trata con cuidado y se toma en consideración la biogeografía y las estrategias de reproducción/dispersión de los diferentes grupos, en caso de conflicto se debería dar prioridad a la bioestratigrafía de ostrácodos sobre las correlaciones puramente litoestratigráficas

Some charophytes from the middle dinosaur member of the Tendaguru formation (Upper Jurassic of Tanzania)

Biostratigraphy and paleoecology of the famous dinosaur beds of Tendaguru Formation, Tanzania, East Africa are still under discussion. Calcareous microfossils have not yet contributed to this question. Four samples from the Middle Dinosaur Member have now yielded charophyte gyrogonites of the species Aclistochara cf. bransonii, Aclistochara cf. minor, Mesochara canellata, and Mesochara harrisi. Considering ammonite datations in under- and overlying members, even their long stratigrapical ranges point to a Kimmeridgian age for the Middle Dinosaur Member of Tendaguru Formation. Salinity tolerances of the species (if autochthonous) suggest a variable environment with partly brackish, partly freshwater influences. Biostratigraphie und Paläoökologie der berühmten Dinosaurier-Fundschichten am Tendaguru Hill in Tansania (Ostafrika) sind bis heute umstritten. Kalkige Mikrofossilien hatten zu dieser Diskussion bisher nicht beigetragen. In vier Proben aus dem Mittleren Dinosauriermergel fanden sich nun Charophyten-Gyrogonite der Arten Aclistochara cf. bransonii, Aclistochara cf. minor, Mesochara canellata und Mesochara harrisi. Trotz generell langer stratigraphischer Reichweiten dieser Arten macht ihr Vorkommen im Zusammenhang mit Ammonitenfunden in unter- und überlagernden Schichten ein Kimmeridgium-Alter des Mittleren Dinosauriermergels wahrscheinlich, während ihre Salinitätstoleranzen (autochthones Vorkommen vorausgesetzt) auf ein wechselhaftes Milieu mit teils schwach brackischen, teils Süßwassereinflüssen hindeuten. doi:10.1002/mmng.1999.4860020115</a

Sedimentary record of coseismic subsidence in Hersek coastal lagoon (Izmit Bay, Turkey) and the late Holocene activity of the North Anatolian Fault

This research was funded by the European Union in the framework of the REL.I.E.F. (Reliable Information on Earthquake Faulting) project (EVG1‐CT‐2002‐00069). Copyright @ 2011 American Geophysical Union.The late Holocene activity of a restraining bend of the northern strand of the North Anatolian Fault in Izmit Bay was investigated by a sedimentological, geochemical, and paleoecological analysis of sediment cores from Hersek coastal lagoon, NW Turkey. The sediment cores show a succession of sedimentary sequences composed of three units separated by gradual transitions. The first unit is composed of a thin layer of shell debris-rich sediment in abrupt contact with the underlying organic-rich deposits. This unit is over-lain by a thick foraminifera-rich mud deposit, and the sequences are capped by an organic-rich mud unit. These sequences are interpreted as silting up, shallowing upward deposits, typical of a lagoon becoming isolated from the sea. We suggest that they represent the sedimentary signature of coseismic subsidence, which was caused by reverse slip at the Hersek bend, and tsunamis in Izmit Bay. Our radiocarbon-dated paleoseismological record indicates (1) the atypical collapse of the hanging wall during the 740 earthquake and (2) subsidence of the footwall during the 987, 1509, and 1719 earthquakes. This study contributes to the understanding of the dynamics of restraining bends, and it highlights the potential of coastal sediments for reconstructing past earthquakes and tsunamis in regions dominated by strike-slip deformations.This article is available through the Brunel Open Access Publishing Fun

Hollywood im Umbruch: Jazz im \u27social problem film\u27 der frühen 50er Jahre

Die Untersuchung der wichtigen Filme der genannten Zeit, ihrer Partituren und begleitendem, gerade zeitgenössischem Textmaterial ergab, daß für ihr Verständnis v.a. die Kenntnis folgender Faktoren von Bedeutung ist: der Entstehungsgeschichte einer Produktion, der im Production-Code festgelegten Bedingungen der amerikanischen Filmzensurbehörde, der soziologischen Rolle der verwendeten Musik in dieser Zeit, schließlich biographischer Details der für die Produktion verantwortlichen Personen. In diesem Beitrag wird anhand des Durchbruchs des Jazz als Element der Filmmusik in den frühen 50er Jahren aufgezeigt, wie die genannten Faktoren bei der Etablierung eines neuen filmmusikalischen Standards ineinandergreifen (können). (DIPF/Orig.

Planktonforaminiferen aus dem Obereozän und Unteroligozän der Bohrung Loburg 1/90 (Sachsen-Anhalt, Deutschland)

Aus der Bohrung Loburg 1/90 im nördlichen Sachsen- Anhalt (Deutschland) werden die Planktonforaminiferen des Obereozän bis Unteroligozän beschrieben und ausgewertet. Die Bohrung liegt am SE-Rand des Nordseebeckens, nordöstlich des Wittenberger Abbruchs. An dieser Störung erfolgte im Paläogen eine deutliche (relative) Absenkung, wodurch nordöstlich des Abbruchs größere Mächtigkeiten des Obereozän/ Unteroligozän vor der Abtragung während der Erosionsphase im späteren Oligozän erhalten blieben. Es werden etwa 85 Arten von Planktonforaminiferen bestimmt, eine Anzahl davon in offener Nomenklatur, was auf den z. T. endemischen Charakter der Fauna hinweist. Bemerkenswert ist das relativ häufige Auftreten von Dipsidripella in den Oberen Schönewalder Schichten (OS). Die oberen OS, etwa 24 m mächtig, lassen sich in die Kalknannoplankton-Zonen NP21 und „NP22“ und die Dinoflagellaten-Zone D12nc einstufen (Köthe 2009). Nach Planktonforaminiferen gehören die OS unter gewissem Vorbehalt in die Zonen E14-16 und O1 (sensu Berggren &amp; Pearson 2006). Diese Einstufung basiert auf dem vereinzelten Auftreten von entsprechenden Leitformen aus der tropischsubtropischen Region (Globigerinatheca semiinvoluta, G. index, „Hantkeninen“). Die Einstufung in die Zone E16 und damit die Grenzziehung Eozän/Oligozän erfolgt nach dem letzten Auftreten von Turborotalia cerroazulensis und „Hantkeninen“ allgemein, gestützt durch das erste Auftreten von Subbotina tapuriensis, die Einstufung in die Zone O1 (Unteroligozän) nach dem letzten Auftreten von Pseudohastigerina micra. Die Eozän/Oligozän-Grenze fällt somit in Loburg in den höheren Abschnitt der OS und den höheren Abschnitt der NP21. Diese Grenzziehung muss allerdings durch weitere Untersuchungen an anderen Bohrungen im nördlichen Sachsen-Anhalt und südlichen Brandenburg getestet werden. Die Abfolge der Zonen entspricht der in niederen Breiten, das letzte Auftreten der Leitformen ist jedoch zeitlich verschoben: G. semiinvoluta und G. index noch in der Zone NP21, letztes Auftreten von T. cerroazulensis und „Hantkeninen“ erst in der höheren NP 21. Die OS werden im Hangenden nicht durch eine biostratigraphische Grenze, sondern durch eine Erosion begrenzt. Nach sequenzstratigraphischer Analyse (Schudack &amp; Nuglisch 2006) fehlen zumindest ein Teil der Maximum Flooding Surface und der Highstand System Tract der OS und damit auch der Zonen O1, D12nc und NP22. Der Rupelbasissand (Rupel 1) gehört nach Köthe (2009) im unteren Abschnitt in die Zone D13; Kalknannoplankton und Planktonforaminiferen fehlen. Der nachfolgende Rupel 2-4 (D14na-b, NP23-24, etwa 260m) lässt sich mit Planktonforaminiferen kaum gliedern und wird insgesamt in die Turborotalia ampliapertura Highest-occurrence Zone (O2) eingestuft, wobei der obere Abschnitt schon in die Globigerina sellii Partial Range Zone und nach der Reichweite von Chiloguembelina cubensis und Tenuitella gemma noch bis in die Zone O4 gehört. Lediglich im oberen Rupel tritt vereinzelt Subbotina brazieri auf

Exhumation of the Sierra de Cameros (Iberian Range, Spain): constraints from low-temperature thermochronology

We present new fission-track and (U–Th)/He data from apatite and zircon in order to reconstruct the exhumation of the Sierra de Cameros, in the northwestern part of Iberian Range, Spain. Zircon fission-track ages from samples from the depocentre of the basin were reset during the metamorphic peak at approximately 100 Ma. Detrital apatites from the uppermost sediments retain fission-track age information that is older than the sediment deposition age, indicating that these rocks have not exceeded 110 8C. Apatites from deeper in the stratigraphic sequence of the central part of the basin have fission-track ages of around 40 Ma, significantly younger than the stratigraphic age, recording the time of cooling after peak metamorphic conditions. Apatite (U–Th)/He ages in samples from these sediments are 31–40 Ma and record the last period of cooling during Alpine compression. The modelled thermal history derived from the uppermost sediments indicates that the thermal pulse associated with peak metamorphism was rapid, and that the region has cooled continuously to the present. The estimated palaeogeothermal gradient is around 86 8C km21 and supports a tectonic model with a thick sedimentary fill (c. 8 km) and explains the origin of the low-grade metamorphism observed in the oldest sediments

Ostracods from a Marmara Sea lagoon (Turkey) as tsunami indicators

This is the post print version of the article. The official published version can be obtained from the link below - Copyright @ Elsevier Ltd.A 352 cm long sediment core from Hersek Lagoon (Gulf of İzmit) was investigated for its ostracod species composition in order to evaluate the potential of ostracods to detect tsunami deposits in coastal environments. The Gulf of İzmit is the eastern bay of the Marmara Sea which is tectonically controlled by the North Anatolian Fault. Ostracod shells are rare in the lower third of the core, which probably represents a coastal wetland environment. According to radiocarbon dating of terrestrial plant remains, this unit was deposited between AD 500 and AD 800. Above, ostracod shells are abundant and dominantly monospecific, composed almost exclusively of the widespread brackish water ostracod Cyprideis torosa. This almost monospecific occurrence indicates the establishment and maintenance of the Hersek Lagoon after AD 800. Three distinct layers of mollusc shells and fragments contain ostracod shells of marine and to a lesser extent non-marine origin in addition to those of C. torosa. The shell layers are further characterized by significant maxima in total ostracod shell numbers. The high concentration of ostracod shells, the higher species numbers and the mixture of marine, lagoonal and non-marine ostracod shells shows that shell layers were formed as high-energy deposits resulting from tsunamis or large storms in the Marmara Sea. The partial occurrence of non-marine ostracod shells in the shell layers possibly indicates that tsunamis with extensive run-ups and significant backwash flows caused the high-energy deposits rather than large storms. The investigated sediments show that lagoonal ostracods can serve as good proxies for tsunamis or large storms through significant variations in total shell numbers, species numbers and the mixing of shells of different origin.Funding was provided by the European Union in the framework of the REL.I.E.F. (RELiable Information on Earthquake Faulting) project (EVG1-CT-2002-00069)

Intra-trackway morphological variations due to substrate consistency: the El Frontal dinosaur tracksite (Lower Cretaceous, Spain).

An ichnological and sedimentological study of the El Frontal dinosaur tracksite (Early Cretaceous, Cameros basin, Soria, Spain) highlights the pronounced intra-trackway variation found in track morphologies of four theropod trackways. Photogrammetric 3D digital models revealed various and distinct intra-trackway morphotypes, which reflect changes in footprint parameters such as the pace length, the track length, depth, and height of displacement rims. Sedimentological analyses suggest that the original substrate was non-homogenous due to lateral changes in adjoining microfacies. Multidata analyses indicate that morphological differences in these deep and shallow tracks represent a part of a continuum of track morphologies and geometries produced by a gradient of substrate consistencies across the site. This implies that the large range of track morphologies at this site resulted from similar trackmakers crossing variable facies. The trackways at the El Frontal site present an exemplary case of how track morphology, and consequently potential ichnotaxa, can vary, even when produced by a single trackmaker