A Framework of Ichthyofaunal Ecostratigraphy of the Oligocene–Early Miocene Strata of the Polish Outer Carpathian Basin
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Annales Societatis Geologorum Poloniae (2006), vol. 76: 1–111. A FRAMEWORK OF ICHTHYOFAUNAL ECOSTRATIGRAPHY OF THE OLIGOCENE–EARLY MIOCENE STRATA OF THE POLISH OUTER CARPATHIAN BASIN Janusz KOTLARCZYK1, Anna JERZMAÑSKA2, Ewa ŒWIDNICKA2 & Teresa WISZNIOWSKA2 1 Department of General and Mathematical Geology, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków, Poland 2 Department of Palaeozoology, Institute of Zoology, University of Wroc³aw, Sienkiewicza, 21, 50-335 Wroc³aw, Poland Kotlarczyk, J., Jerzmañska, A., Œwidnicka, E. & Wiszniowska, T., 2006. A framework of ichthyofaunal ecostrati- graphy of the Oligocene–Early Miocene strata of the Polish Outer Carpathian basin. Annales Societatis Geologorum Poloniae, 76: 1–111. Abstract: The paper presents the results of an analysis of ichthyofaunal variability throughout the section of the Menilite-Krosno Series (MKS) in the Outer Carpathians of Poland. The studied tanathocoenoses were formed at the bottom of a more than 2,000 m deep northern basin of the Tethys, being largely represented by the continental rise and bottoms of its narrow furrows, and – to a lesser degree – the continental slope and slopes of a submarine high. Lateral variability of statististically representative assemblages of tanathocoenoses hosted in thin, isochro- nous horizons is interpreted as a result of both local changes of ichthyocoenoses and the influence of post-mortem relocation of fishes that mainly dwelled the shelf and upper continental slope. Vertical variability, in turn, is considered as a resulting from changeable conditions of the ecological environment, the input and outflow of taxa whose evolution proceeded in the Indo-Pacific area, and the species extinction. Changeability of ichthyofauna within a ca. 16-m.y.-long interval made it possible to document and formally describe 9 zones and 4 subzones of ichthyofauna of ecostratigraphic character. These zones comprise index, representative and accompanying taxa that belong to different ecological groups. Conceptual models of the origin of ichthyofaunal assemblages of individual zones are presented. It is suggested that the origin of assemblage differentiation resulted from the appearance and disappearance of the oxygen minimum zone in the water column, global and local sea level changes, topography of the basin bottom, as well as final basin infilling by sediments of submarine fans. The described and preserved collection of fossil Carpathian fishes, housed at the Department of Palaeozoology of the University of Wroc³aw, requires further specialized palaeontological studies in order to reconstruct a more complete composition of the Oligocene–Early Miocene ichthyofauna. Key words: fossil fish collection, Teleostei, deep-sea sediments, lithostratigraphy, biostratigraphy, fish eco- assemblages, models of changes, ichthyofaunal zonation, ecostratigraphy, Oligocene, Early Miocene, Outer Carpathians, Poland. Manuscript received 22 December 2005, accepted 20 April 2006 INTRODUCTION: A REVIEW OF PALAEOICHTHYOLOGICAL STUDIES IN THE POLISH CARPATHIANS Modern, large-scale studies of the Palaeogene and Neo- principal investigators, namely: Assoc. Prof. Jerzy Jerzmañ- gene ichthyofauna of the Polish Carpathians were initiated ski, geologist, Jan and Ewa Jerzmañski, Ewa Sztolcman- at the turn of the 1950s by a palaeozoologist, Anna Jerz- Kotlarczyk, as well as friends, like Franciszek Ryzner, bota- mañska (Jerzmañska, 1958, 1960), who in the successive nist, and students of the University of Wroc³aw. Inde- years closely cooperated with Carpathian geologists, S. pendent studies of the Carpathian ichthyofauna were carried Jucha (Jerzmañska & Jucha, 1963) and J. Kotlarczyk (see out by Dr. Teresa Œmigielska (Œmigielska, 1962). references). During the 35-years-long studies, the research A close cooperation between palaeozoologists and ge- team included as well A. Jerzmañska’s disciples, palaeo- ologists brought about important progress in research into zoologists Wies³awa Szymczyk and Jacek Œwidnicki, and – the Carpathian ichthyofauna. It was quickly found out that starting from 1972 – Ewa Œwidnicka. Fish exploitation was the section of the Menilite Formation, abundant in fossil also aided by helpful participation of family members of fish, bears a succession of three, superimposed one upon an- 2 J. KOTLARCZYK ET AL. other, clearly different ecological assemblages of ichthyo- evolutionary changes of Teleostei (Jerzmañska & Kotlar- fauna which were provisionally named as the lower bathy- czyk, 1981). Apart from bone fragments, the studies con- pelagic, neritic-sublittoral, and upper bathy-pelagic ones centrated on the variability of fish scales of some common (Jerzmañska & Kotlarczyk, 1968; Kotlarczyk & Jerzmañ- genera (Szymczyk, 1978) in the entire section of the ska, 1976); instead of previously described, chronologically Menilite-Krosno Series, as well as on occasionally occur- unordered, mixed assemblages composed of both shallow ring crab ichthyofauna (Jerzmañska, 1967b) and fragments and deep-water fish. of brown seaweeds. A spectacular finding was identification It was also documented that the characteristic assem- in Zone 6 of a specific assemblage of deep-water fish, pipe- blage of bathy-pelagic fish, described from the shaly Jas³o fish, and air bladder-bearing algae, what justified calling Limestones forming intercalations within the Krosno For- this assemblage a quasi-sargassum one (Jerzmañska & Kot- mation at Sobniów near Jas³o (Jerzmañska, 1960), is re- larczyk, 1975, 1976), predating the recent sargassum assem- peated in an exposure situated some 50 km away, at £ubno blage. near Dynów, although within shales of the Menilite Forma- The third approach included an analysis of lateral extent tion (Jerzmañska & Jucha, 1963). This finding led to a con- of the distinguished zones and an attempt at showing corre- clusion that ichthyofauna of the Outer Carpathians could be lation possibilities of different sections of Menilite beds ex- used for stratigraphic purposes, and confirmed a concept of posed at different sites and situated in different tectonic facies interchanging between the two mentioned formations units throughout the Carpathian arc (Kotlarczyk & Jerz- (Jucha & Kotlarczyk, 1958, 1959; Shakin, 1958; Koszarski mañska, 1980). This attempt was also applied, basing on & ¯ytko, 1961). The latter provided a basis for distinguish- published data pertaining to fish assemblages, to the Palaeo- ing the Menilite-Krosno Series (Jucha & Kotlarczyk, 1961). gene and Neogene sequences of the Caucasus (Jerzmañska Both lithofacies of this series were deposited at the same & Kotlarczyk, 1983), and – later – the Alpine Foredeep and time in the Outer Carpathian flysch basin, namely between Rhine Graben (Kotlarczyk & Jerzmañska, 1988a). the onset of the Oligocene (and in the southern part probably Occasionally, attempts were made at determining the from the Priabonian) through the mid-Burdigalian. The last range of variability of fish assemblages within stratigraphic episode of deposition is represented in the Menilite lithofa- logs and between individual sites (Jerzmañska et al., 1973; cies by the Leszczawka Diatomite Horizon (Kotlarczyk, Kotlarczyk et al., 1975), and at explaining the nature of this 1966). variability (Jerzmañska & Kotlarczyk, 1973, 1979; Jerz- The first summary of palaeontological studies of fish mañska & Kotlarczyk, 1991). comprised in the Menilite beds, based on some 2,000 speci- Due to a number of reasons, no currently-made full mens collected at a dozen or so exposures, was published in lithological documentation was performed at every explo- the Dr. Sc. thesis by A. Jerzmañska in 1968. red site. Detailed lithological-sedimentological logs were The following 25 years witnessed further intensive, sys- compiled for some more important sites only, like those at tematic exploration of ca.150 exposures situated in the Jamna Dolna (Jerzmañska & Kotlarczyk, 1968) or Bachów Outer Carpathians east of the Wis³oka River. Field studies (Jerzmañska & Kotlarczyk, 1975). For some of the expo- resulted in collecting nearly 13,000 fish specimens which sures, only rough sketches were drawn showing the position were described by A. Jerzmañska usually up to the genus of fish-bearing layers within distinguished lithological com- (ca. 7,600 specimens), rarely species (ca. 3,100 specimens), plexes. In most cases, the reason for such an approach was and sometimes only family (ca. 1,100 specimens) or order the lack of clear taxonomic and ecological differentiation of (ca. 400 specimens) levels. It should be mentioned in this fish assemblages among individual layers. At such expo- place that determination up to the genus level is sufficient sures, particularly small ones, exploitation of fish in succes- for drawing ecological and ecostratigraphic conclusions sive seasons was frequently carried out “without determin- (Jerzmañska & Kotlarczyk, 1988; Gregorová, 1997). ing stratigraphic position” (wdsp) in the section, and the A minor part of this collection, numbering ca. 4,000 collected assemblage was treated as representing the entire specimens, was described in publications and catalogued, bed sequence of the exposure. while the remaining 9,000 specimens was accompanied by The collected specimens were labelled in the field by field labels only and required detailed inventory. the name and number of exposure and the layer’s number or Elaboration of this data set included different ap- symbol. A complete inventory was only made for those proaches.