Abstracts

HAGN, Herbert & Winfried KUHN:
Paleozäne Foraminiferen von den Emperor Seamounts, NW-Pazifik (DSDP Leg 55)

Planktonic foraminiferal zonation of DSDP sites 430 A and 433 A-C (Leg 55) indicates Uppermost Paleocene (Morozovella velascoensis-Zone) respectively Upper Middle Paleocene (»Globorotalia« pusilla pusilla-Zone).

Benthonic foraminifera show low diversity with a high number of individuals. Nine new species are described with eight further species partly in open nomenclature. Endemism may be the reason. The Paleocene sediments of well 430 A (Öjin Seamount) suggest a hypersaline facies in the upper part. On the other hand the 110 m thick section of well 433 A-C (Suiko Seamount) indicates a constant ecological habitat.

Sediments of both seamounts exhibit differences in age and facies. They are part of a drowned volcanic island chain with an increasing age from south to north, implying a northward movement of the Pacific Plate. In the lower Paleogene the extinct volcanoes rising above sea level are eroded and colonized by sessil organisms, building up atolls. Rich faunas developed in lagoon areas.

LEISS, Otto:
New interpretations of geodynamics and orogeny as a result of synorogenic cretaceous deposits within the Northern Calcareous Alps

The basin analysis of the Gosauian deposits demonstrates that the sedimentation and the biofacies depend in the lower series of the Gosau from the existing geomorphology being controlled by geodynamic orogenic processes in the basement. Thereby the subduction of Penninic elements represents a dominating factor of orogeny.

The facial studies reveal an early construction of intraplate troughs, at first collecting the alluvial debris of anticlinal elevations before epicontinental conditions can extend. Sedimentological and biofacial analysis indicates a basin geometry of asymmetric shape with flat northern limbs and short steep southern limbs. These basins represent the basin area of wide flexures. The construction of flexures is the response to the spatial shortening provoked by subductional processes, whereby the troughs act as depocentres of synorogenic sediments. While filling the compressional troughs these sediments quickly react to changes of the source areas and of the basin morphology and represent as a whole witnesses of orogenic movements which trace over up to the surface of the Austroalpine block and control the dynamics of sedimentation. It was possible to demonstrate a direct participation of some Creataceous deposits in the slow and steady processes of modelling some highest tectonic units of the Northern Calcareous Alps. The orogenic compression leads to subsidence and steepening of basin flanks. The olistostromes being typical for intraplate troughs mark tectonic processes like the decollement of the basement with the incorporation of partly huge olistolithes. Fractional deformation and decollement develop in the centre of deformation after a long period of sole prevailing of bending stress; hence it follows the nappe piling along listric dislocation planes.

Referring to BLUMER's model of nappe genesis by overfolding (BLUMER 1905), here a formation of nappes is proposed by the process of »undertroughing« with special respect to the »Unterströmungstheorie« of AMPFERER (1906) and AMPFERER & HAMMER (1911 ).

JACOBSHAGEN (1986) described in the Hellenids the synorogenic sedimentary processes dependent on each tectonic unit. The same type of sedimentation with a couplet of a final flysch on the lower tectonic unit and a molasse stage on the higher unit could be found in the Northern Calcareous Alps. Here the final flysch (i.e. synorogenic olistostromes – e.g. Roßfeld Formation) terminates the continuous sedimentation on the lower tectonic unit, while after a hiatus a new sedimentation cycle starts with the molasse-like basal Gosau in the Coniacian on the higher unit.

MOUSSAVIAN, Esmail:
Taxonomische Untersuchungen an »Amphiroa« propria LEMOINE (Corallinaceae/Rhodophyta; Maastricht-Thanet)

LEMOINE described »Amphiroa« propria in 1934 as an articulated corallinacean with a medullary tissue consisting of differing high tiers. A critical study of numerous fertile specimens from Maastrichtian and Paleocene strata of the Eastern Alps results in the fact, that this Amphiroa-like dichotomously branched alga does not possess any of the characteristic features of the genus Amphiroa: a) The thallus is in contrast to the thalli of Amphiroa species nongeniculate, however it shows a peculiar secundary decalcification within the whole central part of medulla. b) The medullary tissue consists of arching tiers of long cells, occasionally alternating with indistinct tiers of short cells. In contrast the Amphiroa species are characterized by regularly alternation of differing high cell rows. c) The most important feature of the alga is the peculiar structure of the asexual reproductive organs: The zonately divided tetrasporangia are in thick-wafled calcareous covers, which are arranged each in small spherical sori. The combination of this 3 features not found in any of the currently known fossil and recent calcareous red algae, especially the unique structure of the sporangia, allowes to establish a new genus, named Pseudoamphiroa.

Pseudoamphiroa propria (LEMOINE) n. comb. represents one of the widespread coralline algae of the Alpine-Carpathian Paleocene. It's stratigraphic range appears to be confined to Maastrichtian-Thanetian. This alga existed in tropic to subtropic water in the same environment as the articulated Corallinaceae.

ABUSCH, Susanne:
Bemerkungen zu den Anoplotherien der Pariser Gipse

An examination of the Anoplotheriid specimens from the Parisian Gypsum confirmed CUVIER's classification into two species: the large didactyle Anoplotherium commune and the smaller (tridactyle) Diplobune secundaria; a tridactyle species of Anoplotherium within the Montmartre fauna cannot be proven at present.

Differences in size within the genus Anoplotherium are interpreted as being sexual dimorphism and varieties of growth forms as they can also be found in comparable recent populations. However, the successive sequences of a great number of generations within fossil populations is a factor which may not be underestimated and is, to some extent, caused by ecological influences.

Moreover, some metrical considerations and those of functional morphology of the Anoplotherium commune, which indicate a highly specialised autopodium structure, shows a trend to better locomotion although the animal can be placed in the group of mediportal types with a habitus similar to the Tapir.

SEYED-EMAMI, Kazem, Gerhard SCHAIRER & Mansour ALAVI-NAÏNI:
Ammoniten aus der unteren Dalichai-Formation (Unterbathon) östlich von Semnan (SE-Alborz, Iran)

For the first time Lower Bathonian ammonites are described from the zigzag zone of the Dalichai Formation north of Gardaneh-Ahovan (ca. 60 km E of Semnan, SE-Alborz, Iran). These comprise 16 genera and 31 species, with the new genus Pseudodimorphinites SEYED-EMAMI and the two new species P. komsi SEYED-EMAMI and P. foersteri SEYED-EMAMI. The fauna is closely related to Central and Northwest Europe.

SCHAIRER, Gerhard:
Die Cephalopodenfauna der Schwammkalke von Biburg (Oberoxford, Südliche Frankenalb): Idoceratinae (Ammonitina)

From the environment of a small sponge-algal »patch reef« from the Upper Oxfordian (Weißer Jura Beta, planula zone) of Biburg near Weißenburg/Bayern (southwestern Frankenalb, Bavaria, W Germany) Idoceras (Subnebrodites) planula (HEHL), I. (S.) laxevolutum (FONTANNES) sensu ZIEGLER, I. (S.) aff. laxevolutum (FONTANNES), I. (S.) minutum DIETERICH, I. (S.) schroederi WEGELE, I. (S.) proteron NITZOPOULOS, ?Nebrodites sp. and Orthosphinctes (Praeataxioceras) sp. are described, and the variability of the species of Idoceras is shown. The distribution of the species of Idoceras in the section of Biburg, their encrusters, and the stratigraphic position of the Biburg section are discussed.