Grzegorz Racki
University of Silesia in Katowice, Earth Sciences, Faculty Member
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The Frasnian–Famennian (F‐F) transition is well exposed in the basinal setting of La Serre (Montagne Noire, France), where oxygen‐deficient conditions prevailed in bottom environments. In this paper, we study the F‐F transition using... more
The Frasnian–Famennian (F‐F) transition is well exposed in the basinal setting of La Serre (Montagne Noire, France), where oxygen‐deficient conditions prevailed in bottom environments. In this paper, we study the F‐F transition using inorganic geochemistry (notably, major elements, redox‐sensitive and/or sulphide‐forming trace metals, and productivity proxies). The results are compared with published data concerning the La Serre section, other F‐F sections and other geological formations also deposited in basinal settings. The very high enrichment in redox and productivity tracers indicates that anoxic conditions prevailed across the F‐F boundary, and that surface productivity was intense. Such deep‐water restricted conditions coupled with high productivity occurred in various places in Late Devonian oceans. Recycling alone cannot account for the intense nutrient supply and therefore the most probable source was via land runoff. We discuss the Eovariscan episode of uplift that stimulated rock weathering, and hence long‐term nutrient supply to the seas.
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ABSTRACT In a recent paper (Heydari, E., Arzani, N., Hassanzadeh, J., 2008. Mantle plume: the invisible serial killer — application to the Permian–Triassic boundary mass extinction. Palaeogeography, Palaeoclimatology, Palaeoecology 264,... more
ABSTRACT In a recent paper (Heydari, E., Arzani, N., Hassanzadeh, J., 2008. Mantle plume: the invisible serial killer — application to the Permian–Triassic boundary mass extinction. Palaeogeography, Palaeoclimatology, Palaeoecology 264, 147–162) the cause of the end-Permian mass extinction was once again associated with the eruption of the Siberian Traps. However, this work considered the vast outpouring of flood basalts to be an incidental sideshow to the main event: the catastrophic release of huge volumes of methane to the atmosphere. This was attributed to a selection of sources – marine gas hydrates, thermogenic methane and methane from permafrost – that have been proposed by many authors previously. Uniquely, they suggest that the mantle plume (envisaged to have sourced the flood basalts) impinged beneath oceanic crust to the north of the Siberian flood basalts and that feeder dykes in the continental slope to the south heated sediments and released methane. There is no evidence for either of these two new proposed facets to end–Permian volcanism. The paper invokes an "oceanic acid bath" kill mechanism and dismisses claims for ocean anoxia at this time instead suggesting that end–Permian oceans were as well ventilated as those pertaining today. This latter claim simply ignores a vast body of sedimentological, palaeoecological and geochemical evidence for widespread anoxia in ocean and shelf settings at this time. The former claim for ocean acidity is equally suspect and based on the notion that a transition from calcite to aragonite-precipitating seas occurred at the Permian–Triassic boundary. However, previous studies have suggested that this interval occurs within a phase of "aragonite seas" and it is significant that most of the principal contributors to carbonate sediment in the Late Permian (calcareous algae and foraminifera) secreted aragonite.
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Research Interests: Geology and Paleontology
IMPROVEMENTS SUGGESTED FOR THE DEVONIAN EUSTATIC CURVE Summary Results of the international symposium on Devonian eustasy in Moscow in July 1994, as well as ideas presented in several recent publications markedly confirmed an overall... more
IMPROVEMENTS SUGGESTED FOR THE DEVONIAN EUSTATIC CURVE Summary Results of the international symposium on Devonian eustasy in Moscow in July 1994, as well as ideas presented in several recent publications markedly confirmed an overall global control of major facies movements by Devonian sea-level fluctuations (Figs 1,2), as supposed by Johnson and co-authors in 1985 (and earlier by House). Refinement and new subdivision of their Euramerican eustatic cyclicity scheme are more and more necessary (Figs 2, 3) toward its standardization in the whole Devonian World. Data from Polish and East European epicontinental sequences are significant in this modification, as exemplified by early Frasnian (llb/c) deepening pulse. More and more numerous recognizable sea-level falls seem to be especially important to understanding of Devonian successions in terms of sequence stratigraphy. Such improved eustatic curve would be reliable chronostratigraphic framework for event interpretation of sedimentar...
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In the history of the study of Meteor Crater, there is an interlude between its initial geologic exploration in early 1890s (finalized by the seminal publication of the volcanic model by Gilbert in 1896) and the spectacular... more
In the history of the study of Meteor Crater, there is an interlude between its initial geologic exploration in early 1890s (finalized by the seminal publication of the volcanic model by Gilbert in 1896) and the spectacular research-prospective activity of Barringer, completed with a meteoritic concept published in 1905. Here it is shown that the period between 1896 and 1905 did not represent a conceptual stasis in solving the mystery of the Arizona crater. Popular interest in the attractive theme was promoted by known scientists, such as Crookes, Holder, and Meyer. However, it was primarily exemplified by the work of Joseph A. Munk. In unnoticed publications from 1903 to 1906, he presented Coon Mountain indubitably as a meteorite crater, along with a proposal to adopt the appropriate name of Meteorite Mountain for this natural curiosity. His proimpact geologic arguments were widely repeated in later papers. In addition, Munk was a visionary pioneer in the propagation of the geotourist attraction represented by this geologic wonder, as manifested in his well-read guidebook Arizona Sketches. Furthermore, a surprising but significant issue is the hidden stimulating role of Fred W. Volz, known hitherto as a local businessmen and meteorite dealer. Especially in the light of Munk’s publications, Volz is shown to have been an insightful observer of geologic phenomena, including a progressive revival of Gilbert’s incipient conception of a buried “stellar body” under Coon Mountain (rejected by Gilbert himself). Even if this activity can be downgraded as only popular writing, Munk and (to some degree) Volz ought to be known at least as inspiring propagators and therefore pioneers of the meteorite hypothesis regarding Meteor Crater, independently of the widely known Barringer engagement.
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Abstract The Frasnian–Famennian (F–F) event may be recognized in various facies areas in South China. In the pelagic cherty basin facies, both Lower and Upper Kellwasser events can seemingly be recognized. In the deeper water carbonate... more
Abstract The Frasnian–Famennian (F–F) event may be recognized in various facies areas in South China. In the pelagic cherty basin facies, both Lower and Upper Kellwasser events can seemingly be recognized. In the deeper water carbonate facies, the F–F event level is well controlled in light of conodont biostratigraphy. In the shallow water carbonate and mixed carbonate-shale facies, the F–F boundary may be defined by clear taxonomic distinction in benthic fossils (articulate brachiopods and corals) as well as evidence from minor pelagic fossils. Post-extinction recovery rate of benthic organisms differs in different facies settings and different taxonomic groups. In open shallow water platform to inter-platform depression areas, brachiopods seem to recover quickly, probably in the Middle Pa. triangularis Zone; benthic ostracodes seem to recover at a later stage; recovery of rugose corals did not happen until the uppermost Famennian. Three steps of the F–F mass extinction are postulated: 1) extinction of diverse brachiopods (including most atrypids); 2) extinction of pelagic conodonts; 3) extinction of both benthic faunas (very abundant and diverse rugose corals and ostracodes) and pelagic conodonts. Evidence of an end-Frasnian regression in South China is clear, particularly in shallow water settings. However, in deeper water settings, the picture is complicated, with evidence of both sea level rise and fall in the latest Frasnian. It may be assumed from overall data so far known that crustal evolution itself and associated multiple volcanic/hydrothermal activities may have mainly caused frequent and rapid climatically warming-cooling alterations and sea level changes as well as marine ecologic collapse (eutrophication, microbial blooming, seawater acidification, and anoxia), which may explain the F–F extinction pattern in South China.
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The dC and dO iso tope data from both fos sil (Mio cene) and mod ern fresh wa ter bi valve shells of fam ily Unionidae from Po land (spe cies Margaritifera flabellatiformis and Unio tumidus, re spec tively) show a sim i lar, trun cated si... more
The dC and dO iso tope data from both fos sil (Mio cene) and mod ern fresh wa ter bi valve shells of fam ily Unionidae from Po land (spe cies Margaritifera flabellatiformis and Unio tumidus, re spec tively) show a sim i lar, trun cated si nu soi dal pat tern. The iso to pic pro files of the shells are vis i bly marked by three growth stages, linked with a pro gres sive loss of en vi ron men tal re cord be cause of de clin ing intra-an nual biocarbonate ac cre tion rate. The ju ve nile and gerontic phases ex hibit gen er ally more pos i tive and sta ble (pla teau) iso to pic pat tern than the mid-age stage. An in creas ing dC trend is typ i cal for the fi nal life stage, likely in flu enced by nu tri ent over load ing, re vers ing the ten dency to wards C de ple tion through out the in di vid ual’s life in duced by met a bolic pro cesses. Due to the pro gres sive loss of en vi ron men tal sig nals through on tog eny, these ini tial and fi nal iso to pic pro file seg ments prob a bly ...
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Widespread occurrences of silica in the Devonian limestones of the Holy Cross Mts and Cracow-Silesia region are recognized as the product of superimposed processes which probably occurred during later diagenesis. The two main stages... more
Widespread occurrences of silica in the Devonian limestones of the Holy Cross Mts and Cracow-Silesia region are recognized as the product of superimposed processes which probably occurred during later diagenesis. The two main stages ofsilicification were most likely separate events resulting from progressive calcitization of opaline skeletons and secondary silica remobilization. Older (?pre-Permian) silicification(s) are associated with silica migration toward deposits rich in preferred skeletal grains; it can be seen in replaced fossils. as well as in replacive and drusy quartz megacrystals. The chertlflcauon is a surprisingly young, post-tectonic phenomenon, as indicated by a vein-type occurrence and substitution of late calcite veinlet networks paired with a very low maturity of the silica. This event was associated with a profound disturbance of physiochemical equilibrium within the rock massif (?after Laramide uplift); links to primary opal-rich facies point to extremely short-...
... 6). Acknowledgements We thank Jason Ali and Tom Worsley for their comments on an early version of this arti-cle. We appreciate thorough reviews by Andy Saunders and Sara Pruss, which have led to final improvements in the manuscript. ...
... Acknowledgements We thank Nezha Lazreq, Catherine Cr6nier, Ivan Berra, Said Chakiri, and Alain Herbosh for their assistance during field work, Jacques Morel for the ICP-MS measurements at CRPG-CNRS (Vandceuvre-les-Nancy, France), and... more
... Acknowledgements We thank Nezha Lazreq, Catherine Cr6nier, Ivan Berra, Said Chakiri, and Alain Herbosh for their assistance during field work, Jacques Morel for the ICP-MS measurements at CRPG-CNRS (Vandceuvre-les-Nancy, France), and Franqois Baudin for the Rock ...
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A tephra-rich cherty-clayey Famennian succession within the major Brzeźnica olistostrome in the Bardo Mountains, Central Sudetes, SW Poland, preserves a record of the lost ocean later incorporated into the Variscan orogenic belt.... more
A tephra-rich cherty-clayey Famennian succession within the major Brzeźnica olistostrome in the Bardo Mountains, Central Sudetes, SW Poland, preserves a record of the lost ocean later incorporated into the Variscan orogenic belt. Fluctuating but mostly oligotrophic regimes and low primary production levels were influenced by weak upwelling below the perennial oxygen minimum zone, which controlled the interplay between biosiliceous and siliciclastic deposition in the oceanic basin, with episodic oxygen deficiency. The Hangenberg Black Shale has been identified in this oceanic setting based on its characteristics described worldwide (including mercury enrichments). A tectonic uplift of the sediment source area near the Devonian-Carboniferous boundary, recorded in the distinguishing provenance signal of old continental crust, was paired with a global transgression, anoxia, and volcanic episode in an interglacial interval. Assuming paleogeographic affinity with the Bavarian facies of th...
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British paleontologist and stratigrapher, is presented at length by his former student as the father of neocatastrophism. The ideas of violent events and processes as geological agents were revived following a long-term predominance of... more
British paleontologist and stratigrapher, is presented at length by his former student as the father of neocatastrophism. The ideas of violent events and processes as geological agents were revived following a long-term predominance of the paradigm of uniformitarianism (‘‘natural processes are steady across time and space’’) and the gradual theory of evolution (e.g., Palmer 2003). The neocatastrophism renaissance by the late twentieth century was paired with the successful emergence of two interconnected concepts: 1) the rare event principle and 2) the bolide impact theory of mass extinction. In fact, the birth of both these ideas took place 220 years ago. In his thought-provoking books, Ager (1973, 1993) emphasized the concept of infrequent events in Earth history, with credit given to Peter E. Gretener (1926–2008); incidentally, this priority is totally omitted by Nield (2011). Gretener, a little-known geologist from the University of Calgary, introduced the notion of rare events ...
The lower Frasnian (transitans Zone with Ancyrodella priamosica = MN 4 Zone) rhythmic basin succession of marly limestones and shales (upper Szydówek Beds) at Kostomoty, western Holy Cross Mts., Central Poland, contains a record of the... more
The lower Frasnian (transitans Zone with Ancyrodella priamosica = MN 4 Zone) rhythmic basin succession of marly limestones and shales (upper Szydówek Beds) at Kostomoty, western Holy Cross Mts., Central Poland, contains a record of the transgressive-hypoxic Timan Event in this drowned part of southern Laurussian shelf. The unique facies consists of organic-rich marly shales and a distinctive pyritic, goniatite level, 1.6 m thick. The faunal assemblage is dominated by pyritized shells of diminutive mollusks with cephalopods (in-cluding goniatites Epitornoceras and Acanthoclymenia), buchioline bivalves (Glyptohallicardia) and styliolinids. This interval is marked by moderately low Th/U ratios and pyrite framboid size distributions suggestive of dysoxic rather than permanent euxinic condi-tions. The scarcity of infauna and bioturbation resulted in finely laminated sedimentary fabrics, as well as the low diversity of the pre-sumed pioneer benthos (mostly brachiopods). In the topmost par...
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Preliminary review of taxonomy of the brachiopod order AĘpida and its stratigraphic distribution in the late Frasnian Kellwasser Crisis of several regions of Laurussia, westem Siberia and South China point to their moderate diversity and... more
Preliminary review of taxonomy of the brachiopod order AĘpida and its stratigraphic distribution in the late Frasnian Kellwasser Crisis of several regions of Laurussia, westem Siberia and South China point to their moderate diversity and stepdown but irregular extinction pattern. The distinctive character of the late Frasnian atrypid fauna is empha-sised by several relict genera, marked by recurrent and possibly aberrant characters (mainly in ornamentation types), tendency to size reduction and homeomorphy in some taxa. The transgressive/hypoxic Lower Kellwasser Event and preceding eustatic changes during the Palmatolepis rhenanaZone had only a regional destructive effect, and were linked rathęr to an enhanced dispersal of the last generic set of aĘpids. The VariaĘpi-nae, Spinatrypinae and Iowatryp,a-group seem to belong to the latest surviving atrypids. The final demise of the remaining atrypids (and some other articulate brachiopods, e.g., gypidulids) coincided with the fransgress...
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Well exposed Early–Middle Frasnian (E–MF, Palmatolepis transitans to Palmatolepis punctata zonal interval) deposits of the Holy Cross Mountains, in particular the reference Wietrznia section at Kielce, were studied in terms of conodont... more
Well exposed Early–Middle Frasnian (E–MF, Palmatolepis transitans to Palmatolepis punctata zonal interval) deposits of the Holy Cross Mountains, in particular the reference Wietrznia section at Kielce, were studied in terms of conodont biofacies dynamics. Frequency of the conodont elements has been controlled mostly by depositional rate in hemipelagic muddy lithofacies and post−mortem gravity sorting during lateral redeposition in storm−generated, talus−like and encrinite layers. The conodont assemblages are dominated by a highly varying proportion of polygnathid, icriodontid, and ancyro− dellid fauna. Major biofacies turnovers coincided with the deepening pulses corresponding to Timan, Middlesex, and early Rhinestreet global events. Trends in the conodont dynamics, mortality, and diversity point that the biotic shifts also coincide with the large−scale 13C excursions as a record of changing trophic conditions during the major biogeochemical perturba− tion. A gradual decline of the ...
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Devonian bryozoans have been investigated from two Givetian to Frasnian localities in the Holy Cross Mts (Central Po− land), representing fossiliferous ramp slope facies of the Kostomłoty facies zone (north−western periphery of the Kielce... more
Devonian bryozoans have been investigated from two Givetian to Frasnian localities in the Holy Cross Mts (Central Po− land), representing fossiliferous ramp slope facies of the Kostomłoty facies zone (north−western periphery of the Kielce carbonate platform). Thirteen genera belonging to four families and three orders have been identified. Bryozoans show close relation to previously described Givetian and Frasnian bryozoan faunas of France, but also some affinities to east− erly regions (e.g., Kuzbass). The main immigration episodes are related to late Givetian and middle Frasnian deepening pulses. The replacement of locally rich and diverse Givetian carbonate bank faunas by overall impoverished Frasnian reef−complex associations largely corresponds to a major extinction event in the evolutionary history of Bryozoa. Five
Late Frasnian Atrypida (Brachiopoda) from the Holy Cross Mountains, Poland, include 15 taxa and were widely distributed in foreslope habitats of the declining Dyminy Reef complex. The Palmatolepis semichatovae transgression, followed by... more
Late Frasnian Atrypida (Brachiopoda) from the Holy Cross Mountains, Poland, include 15 taxa and were widely distributed in foreslope habitats of the declining Dyminy Reef complex. The Palmatolepis semichatovae transgression, followed by the transgressive/hypoxic Lower Kellwasser (KW) Event during the Palmatolepis rhenana Zone did not have catastrophic effects for atrypid faunas, but were rather associated with the appearance of a new species group comprising Iowatrypa, Waiotrypa, Costatrypa, Spinatrypina , Desquamatia and Radiatrypa. Stepdown demise of the biota started during the inter-KW regression, and culminated as a result of increasing stress during the Upper Kellwasser Event in the late Palmatolepis linguiformis Zone, mainly due to catastrophic sea level changes and anoxia, possibly linked to oceanic thermal changes (cooling) and nutrification pulses. The extinction pattern was diachronous and facies-controlled in this area, and the last atrypid survivors reached the Frasnian...
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Preliminary review of taxonomy of the brachiopod order AĘpida and its stratigraphic distribution in the late Frasnian Kellwasser Crisis of several regions of Laurussia, westem Siberia and South China point to their moderate diversity and... more
Preliminary review of taxonomy of the brachiopod order AĘpida and its stratigraphic distribution in the late Frasnian Kellwasser Crisis of several regions of Laurussia, westem Siberia and South China point to their moderate diversity and stepdown but irregular extinction pattern. The distinctive character of the late Frasnian atrypid fauna is emphasised by several relict genera, marked by recurrent and possibly aberrant characters (mainly in ornamentation types), tendency to size reduction and homeomorphy in some taxa. The transgressive/hypoxic Lower Kellwasser Event and preceding eustatic changes during the Palmatolepis rhenanaZone had only a regional destructive effect, and were linked rather to an enhanced dispersal of the last generic set of aĘpids. The VariaĘpinae, Spinatrypinae and Iowatryp,a-group seem to belong to the latest surviving atrypids. The final demise of the remaining atrypids (and some other articulate brachiopods, e.g., gypidulids) coincided with the fransgressiv...
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Early to Middle Frasnian (E–MF) epicontinental sequences are investigated in five representative localities of the Holy Cross Mountains and Cracow region, with emphasis on conodont biostratigraphy, to evaluate the regional stratigraphic... more
Early to Middle Frasnian (E–MF) epicontinental sequences are investigated in five representative localities of the Holy Cross Mountains and Cracow region, with emphasis on conodont biostratigraphy, to evaluate the regional stratigraphic and biotic context of a major biogeochemical perturbation in global carbon cycling. Conodont associations from the Palmatolepis transitans to Palmatolepis punctata Zone boundary beds are dominated by the shallow−water polygnathid and ancyrodellid fauna in the South Polish epicontinental successions, and first appearances of index palmatolepid spe− cies are delayed due to facies control of pelagic environments during intermittent drowning of the carbonate shelf. Thus, identification of the zonal boundary is based mainly on species of Ancyrodella, and five distinctive ancyrodellid levels in the succession across the E–MF interval enable refined correlation of the sections studied, especially when paired with chemostratigraphic proxies. Prominent conodo...