Krzysztof Birkenmajer
Polish Academy of Sciences
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Featured researches published by Krzysztof Birkenmajer.
Earth and Planetary Science Letters | 1992
Randall A. Keller; Martin R. Fisk; William M. White; Krzysztof Birkenmajer
Bransfield Strait is a narrow marginal basin separating the South Shetland Islands from the northern end of the Antarctic Peninsula. Quaternary volcanism occurs in the strait as subaerial and submarine volcanoes aligned on the inferred axis of rifting, and as two subaerial, off-axis volcanoes on the northern margin of the strait. The Bransfield Strait lavas are similar to published analyses from other marginal basins, ranging from basalts and basaltic andesites to trachytes. They exhibit moderate enrichments in alkali and alkaline earth elements relative to high-field-strength elements that are typical of many back-arc basin basalts. The seamount basalts have trace element chemistry similar to enriched mid-ocean ridge basalts (E-MORB), but with variously higher alkali and alkaline earth element concentrations and, frequently, lower Nb. Low-pressure fractional crystallization accounts for most of the compositional variation within individual volcanoes, but it does not explain intervolcano differences even though the volcanoes are closely spaced and presently or recently active. Melting of depleted mantle mixed with 0.5–2% crust or sediment explains the isotopic and trace element variations not accounted for by magma chamber processes. The off-axis volcanoes are the products of less partial melting than the on-axis volcanoes. One of the off-axis volcanoes also contains more of an enriched component in its source. Some of the lavas have Rb/Sr too low to account for their 87Sr/86Sr, perhaps due the loss of Rb during mantle metasomatism or interaction between slab-derived fluids and the mantle source of the basalts. Strontium, neodymium, and 207Pb/204Pb isotopic signatures remained constant during the transition from Tertiary island arc volcanism to Quaternary marginal basin volcanism, but 206Pb/204Pb increased. High CeN/SmN of basalts from some volcanoes requires residual garnet in the source. Thus the young (15–25 Ma at the trench) subducted slab is either deeper than 60 km beneath the volcanoes, or it has fractured and is no longer a coherent barrier to melts generated below it.
Cretaceous Research | 1992
Krzysztof Birkenmajer; M.A. Gasiński
During the Albian and Cenomanian, the Pieniny Klippen Belt Basin, a part of the Carpathian geosynclinal domain, showed a clear differentiation into an axial deepest part represented by the Pieniny and Branisko successions and two marginal zones, a southern (Nizna and Haligovce successions, in Slovakia) and a northern zone (in Poland and Slovakia) represented by the Niedzica, Czertezik and Czorsztyn successions, becoming progressively more shallow towards the north. Five palaeobathymetric foraminiferal associations have been distinguished in the axial and northern marginal zone sediments of the Klippen Basin, corresponding to: ‘A’ shelf and upper slope: relatively large proportion of nodosariids and miliolids (Czorsztyn succession); ‘B1’ middle part of slope; oligotaxic planktonic assemblage dominant (Niedzica through Branisko successions and northern part of the Pieniny succession); ‘B2’ middle part of slope: larger proportion of agglutinated foraminifers, association characteristic of sediments influenced by turbidites (submarine flyschoid channels in the Branisko succession); ‘Cl’ middle and lower parts of slope: scarce microfauna, Hedbergella and textularids dominant (Pieniny succession, middle part); ‘C2’ slope/abyssal plain transition, close to foraminiferal lysocline (probably about 3500m below sea level): scarce specimens corroded and slightly dissolved (Pieniny succession, southern part).
Archive | 1999
Krzysztof Birkenmajer
The great global glaciations were a cyclic though rather infrequent phenomenon in the history of the Earth. The Late Palaeozoic (330–270 Ma), the Early Palaeozoic (about 450 Ma), probably also the Late Proterozoic (Vendian: about 600 Ma) glaciations, affected large continents in high latitude south polar position. Asynchronous glaciation affected the southern and the northern continents during the Cenozoic. In Antarctica, it started during Eocene (at about 50 Ma), its ice-cap at sea-level developed in Early Oligocene (at 32–30 Ma), and became a semi-permanent feature of this continent since Early Miocene (22–20 Ma). In the Arctic, the glaciation started much later, during Pliocene (at about 3.4 Ma). Its Pleistocene (2–0.1 Ma) ice-sheets developed around a relatively small Arctic Ocean in northern North America and Eurasia, and in Greenland. Presently, the Arctic glaciation is reduced to a few much reduced ice-caps, the Greenland and the Svalbard ones being the largest. There is a direct correlation between global glaciations and world-ocean level recognizable in Cenozoic marine geological record: low stands of sea level correspond to glacial epochs, while high stands to interglacials. Global-scale glaciations have both terrestrial and extraterrestrial causes.
Polish Polar Research | 2005
Krzysztof Birkenmajer; A Gazdzicki; K.P. Krajewski; A. Przybycin; A. Solecki; Andrzej Tatur; H.I. Yoon
Annales Societatis Geologorum Poloniae | 1989
Krzysztof Birkenmajer; Nestor Oszczypko
Acta Geologica Polonica | 1972
Krzysztof Birkenmajer
Lethaia | 1971
Krzysztof Birkenmajer; David L. Bruton
Bulletin of the Polish academy of sciences. Earth sciences | 1986
Krzysztof Birkenmajer; M. C. Delitala; W. Narebski; M. Nicoletti; C. Petrucciani
Annales Societatis Geologorum Poloniae | 2002
Krzysztof Birkenmajer; Zoltán Pécskay; Jacek Grabowski; Marek W. Lorenc; Paweł P. Zagożdżon
Studia Geologica Polonica | 2000
Krzysztof Birkenmajer; Z. Pécskay