Sarmatian and Pannonian mollusks from Pécs-Danitzpuszta, southern Hungary: a unique local faunal succession

As the almost 200-year palaeontological research revealed, the geographical distribution of various fossil mollusk faunas in deposits of the late Neogene Lake Pannon displays a regular pattern. The lake basin was filled by lateral accretion of sediments, resulting in condensed sedimentary successions in the distal parts of the basin and successively younger shallow-water deposits from the margins towards the basin center. Exposed intra-basin basement highs, however, broke this strict pattern when they acted as sediment sources during the lake’s lifetime. The Mecsek Mts in southern Hungary was such an island in Lake Pannon during the early late Miocene. Deposition of the 200 m thick Sarmatian–Pannonian sedimentary succession in Pécs-Danitzpuszta at the foot of the Mecsek Mts was thus controlled by local tectonic and sedimentary processes, resulting in a unique succession of facies and mollusk faunas. A typical, restricted marine Sarmatian fauna is followed by a distinct freshwater or oligohaline interval, which, according to micropalaeontological evidence, still belongs to the Sarmatian. Although poor preservation of fossils does not allow firm conclusions, it seems that freshwater Sarmatian snails were the ancestors of the brackish-water-adapted early Pannonian pulmonate snail taxa. The successive “Sarmatian-type” dwarfed cockle fauna is similar to those widely reported from the Sarmatian–Pannonian boundary in various parts of the Pannonian Basin; however, a thorough taxonomic study of its species is still lacking. The bulk of the sedimentary succession corresponds to the sublittoral to profundal “white marls,” which are widespread in the southern Pannonian Basin. In Croatia and Serbia, they are divided into the Lymnocardium praeponticum or Radix croatica Zone (11.6–11.4 Ma) below, and the Congeria banatica Zone (11.4–9.7 Ma) above; this division can be applied to the Pécs-Danitzpuszta succession as well. Sedimentation of the calcareous marl, however, ceased at Pécs-Danitzpuszta at about 10.5–10.2 Ma ago (during the younger part of the Lymnocardium schedelianum Chron), when silt was deposited with a diverse sublittoral mollusk fauna. Similar faunas are known from the Vienna Basin, southern Banat, and other marginal parts of the Pannonian Basin System, but not from Croatia and Serbia, where deposition of the deep-water white marls continued during this time. Finally, the Pécs-Danitzpuszta succession was capped with a thick, coarse-grained sand series that contains mollusk molds and casts representing a typical littoral assemblage. This littoral fauna is well-known from easternmost Austria, northern Serbia, and northwestern Romania, but never directly from above the sublittoral L. schedelianum Zone. The fauna is characteristic for the upper part of the Lymnocardium conjungens Zone and has an inferred age of ca. 10.2–10.0 Ma. The Pécs-Danitzpuszta succession thus allows to establish the chronostratigraphic relationship between mollusk faunas that have not been observed in one succession nor in close proximity to each other in other parts of the Pannonian Basin.

Evaluation of Boulder Deposits Linked to Late Neogene Hurricane Events

The Neogene is a globally recognized interval of geologic time that lasted from 23 until 1 [...]

Late Neogene Radiolaria from the East Coast Deformed Belt, New Zealand

<p>Within the East Coast Deformed Belt there are a number of Late Neogene sedimentary basins with relatively deep-water sediments which, at places, contain abundant radiolarian skeletons. The region was subject to relatively open ocean circulation patterns during the Neogene which, combined with the input of rhyolitic glass shards, has enhanced the siliceous microfossil preservation. A short review of the silica budget is presented and discussed in relation to the preservation of siliceous microfossils in the New Zealand sequences. Techniques were developed to extract and quantitatively study fossil Radiolaria from some of the relatively barren shelf/slope sediments. One hundred and thirty-eight radiolarian taxa are described, most of which can be assigned at the generic level, but thirty-one of which can not be assigned specific names and may eventually prove to be new species. The radiolarian zonation presented is based on detailed analysis of 155 samples from 26 sections and sites ranging in age from basal Tongaporutuan (early Late Miocene) to middle Nukumaruan (early Pleistocene). Sediments of the Kapitean (uppermost Miocene) were generally deposited in shallow water environments or are missing in unconformities in the East Coast Deformed Belt, consequently the radiolarian zonation is based on very poor data in this time segment. Also upper Opoitian and Waipipian (middle Pliocene) sediments, although at places deposited in relatively deep water, generally lack siliceous tuffs, and radiolarian preservation is poor. Five major radiolarian zones can be recognised: Diartus hughesi Zone, Didymocyrtis sp. A Zone, Didymocyrtis sp. A Zone, Didymocyrtis tetrathalmus tetrathalmus Zone, Lamprocyrtis heteroporos Zone, and Lamprocyclas gamphonycha Zone. In samples with good radiolarian preservation six subzones can be identified. The Diartus hughesi Zone can be divided into the Heliodiscus umbonatum Subzone, Didymocyrtis laticonus Subzone, Heliodiscus asteriscus forma large pores Subzone, and Anthocyrtidium ehrenbergi pliocenica Subzone. Additionally the Didymocyrtis tetrathalmus tetrathalmus Zone can be divided into the Lychnocanium sp. aff. grande Subzone and Lamprocyrtis hannai Subzone. The bioevents that define the zonal boundaries are discussed along with other biostratigraphically useful radiolarian datums. These zones and zubzones are correlated to the foraminiferal zonation which in turn has been related, in part, to the paleomagnetic time scale. Correlation are then made with other radiolarian zonations in the north Pacific, tropics, and southern ocean. Points to emerge from these correlations include the apparent provincialism in the transition from Stichocorys delmontense to Stichocorys peregrine in the tropical Pacific. This transition has been reported to occur during approximately 1.5Ma but in New Zealand occurs over a time segment of at least 5.5Ma. The first appearance of Lamprocyclas gamphonycha appears to be an isochronous datum level in temperate radiolarian faunas of the northern and southern Pacific. The last appearance datum of Diartus hughesi at about 7.5Ma is in good agreement with its level in the tropics. The presence of this taxon in lower Gilbert Antarctic cores suggests either a grossly diachronous event between tropical/temperate areas and the southern ocean or, more probably, a misinterpretation of the paleomagnetic signature from key southern ocean piston cores. If the latter situation is the case then the real age estimates on the "Pre middle Gilbert" southern ocean diatom and silicoflagellate stratigraphies are questionable because they are based on the same key cores. Statistical faunal analysis shows that during the Miocene there was not much change in the radiolarian faunas with time and a major change, probably climatically controlled, took place across the Miocene/Pliocene boundary. Variability in preservation has probably affected the faunas to obscure more precise time variation although post-Miocene faunas indicate that some is present. In conclusion, the Radiolaria, although not as common in the fossil record as the foraminifera, definitely contribute to New Zealand Late Neogene integrated stratigraphy and suggest that our knowledge could be greatly enhanced by the study of other siliceous microfossil groups.</p>

Ice Induced Sea Level Change in the Late Neogene

<p>Two independent records of latest Neogene (2,0 - 6.0 Ma.) glacioeustasy are presented, one of Antarctic ice volume from East Antarctica and the other of eustatic sea level from the South Wanganui Basin, New Zealand. Glacial deposits in the Transantarctic Mountains (Sirius Group) and sediment at the Antarctic continental margin provide direct evidence of Antarctic ice sheet fluctuation. Evidence for deglaciation includes the occurrence of Pliocene marine diatoms in Sirius Group deposits, which are sourced from the East Antarctic interior. K/Ar and 39Ar/40Ar dating of a tuff in the CIROS-2 drill-core confirms their Pliocene age at high latitudes (78 [degrees] S) in Antarctica. Further evidence for Antarctic ice volume fluctuation is recorded by glaciomarine strata from the Ross Sea Sector cored by the CIROS-2 and DVDP-11 drill-holes. Magnetostratigraphy integrated with Beryllium-10, K/Ar and 39Ar/40Ar dating provides a high resolution ([plus or minus] 50 k.y.) chronology of events in these strata. In the Wanganui Basin, New Zealand, a 5 km thick succession of continental shelf sediments, now uplifted, records Late Neogene eustatic sea level fluctuation. In the Late Neogene, basin subsidence equalled sediment input allowing eustatic sea level fluctuation to produce a dynamic alternation of highstand, transgressive, and lowstand sediment wedges. This record of Late Neogene sea level variation is unequalled in its resolution and detail. Magnetostratigraphy provides a high resolution chronology for these sedimentary cycles as well as magnetic tie lines with the Antarctic margin record in McMurdo Sound. These two independent records of Late Neogene glacioeustasy are in good agreement and record the following history: The Late Miocene and Late Pliocene are times of low 'base level' glacioeustasy (here termed glacialism, rather than glacial), with growth of continental-scale ice sheets on the Antarctic continent causing a lowering of global sea level. The Early Pliocene was a time of high 'base level' glacioeustasy (here termed interglacialism, rather than interglacial), driven by collapsing of continental-scale ice sheets to local and subcontinental ice caps. The middle Pliocene is marked by a move into glacialism with an increasing 'base level' of glacioeustatic fluctuation. Higher-order glacial advances and associated eustatic sea-level lowering occurred at approximately 3.5 and 4.3 Ma., separating the Early Pliocene into 3 sea-level stages. Still higher-order glacioeustatic fluctuations are recognised in this study, with durations of 50 Ka. and 100 - 300 Ka.. The 100 - 300 Ka. duration cycles are prominent during interglacialisms, and the 50 Ka. duration cycles are prominent during glacialisms. These shorter duration fluctuations in glacioeustasy have already been recognised as glacial/deglacial cycles from detailed studies of the Quaternary. Four orders of sea-level fluctuation are recognised within the Late Neogene, these are of approximately 0.05 Ma., 0.1-0.3 Ma., 2 Ma., and 4 Ma. in duration. The 2 Ma. and 4 Ma. duration cycles are subdivisions of the third order cyclicity recognised by Vail et al. (1991) (referred to here as cyclicity orders 3a and 3b). The 0.1-0.3 Ma. duration cycles are a subset of the fourth order cyclicity recognised Vail et al. (1991), and the 0.05 Ma. Duration cycles are a subset of the 5 th order cyclicity recognised by Vail et al. (1991). 3a, 3b and 4 th order sea level fluctuations are driven by fluctuations in the volume of the Antarctic Ice Sheet. Fifth order sea level fluctuations are also suggested to be at least partially driven by fluctuations in the volume of the Antarctic Ice Sheet. Milankovitch cyclicities in glacioeustasy (<100 Ka., fifth order cyclicity) are prominent in the geologic record at times when there is large scale glaciation (glacialism) of the Antarctic Continent (e.g. for the Pleistocene). Conversely, at times when the Antarctic continent is in a deglaciated state (deglacialism) fourth order cyclicity is more prominent, with Milankovitch cyclicities present at a parasequence level.</p>

Ice Induced Sea Level Change in the Late Neogene

<p>Two independent records of latest Neogene (2,0 - 6.0 Ma.) glacioeustasy are presented, one of Antarctic ice volume from East Antarctica and the other of eustatic sea level from the South Wanganui Basin, New Zealand. Glacial deposits in the Transantarctic Mountains (Sirius Group) and sediment at the Antarctic continental margin provide direct evidence of Antarctic ice sheet fluctuation. Evidence for deglaciation includes the occurrence of Pliocene marine diatoms in Sirius Group deposits, which are sourced from the East Antarctic interior. K/Ar and 39Ar/40Ar dating of a tuff in the CIROS-2 drill-core confirms their Pliocene age at high latitudes (78 [degrees] S) in Antarctica. Further evidence for Antarctic ice volume fluctuation is recorded by glaciomarine strata from the Ross Sea Sector cored by the CIROS-2 and DVDP-11 drill-holes. Magnetostratigraphy integrated with Beryllium-10, K/Ar and 39Ar/40Ar dating provides a high resolution ([plus or minus] 50 k.y.) chronology of events in these strata. In the Wanganui Basin, New Zealand, a 5 km thick succession of continental shelf sediments, now uplifted, records Late Neogene eustatic sea level fluctuation. In the Late Neogene, basin subsidence equalled sediment input allowing eustatic sea level fluctuation to produce a dynamic alternation of highstand, transgressive, and lowstand sediment wedges. This record of Late Neogene sea level variation is unequalled in its resolution and detail. Magnetostratigraphy provides a high resolution chronology for these sedimentary cycles as well as magnetic tie lines with the Antarctic margin record in McMurdo Sound. These two independent records of Late Neogene glacioeustasy are in good agreement and record the following history: The Late Miocene and Late Pliocene are times of low 'base level' glacioeustasy (here termed glacialism, rather than glacial), with growth of continental-scale ice sheets on the Antarctic continent causing a lowering of global sea level. The Early Pliocene was a time of high 'base level' glacioeustasy (here termed interglacialism, rather than interglacial), driven by collapsing of continental-scale ice sheets to local and subcontinental ice caps. The middle Pliocene is marked by a move into glacialism with an increasing 'base level' of glacioeustatic fluctuation. Higher-order glacial advances and associated eustatic sea-level lowering occurred at approximately 3.5 and 4.3 Ma., separating the Early Pliocene into 3 sea-level stages. Still higher-order glacioeustatic fluctuations are recognised in this study, with durations of 50 Ka. and 100 - 300 Ka.. The 100 - 300 Ka. duration cycles are prominent during interglacialisms, and the 50 Ka. duration cycles are prominent during glacialisms. These shorter duration fluctuations in glacioeustasy have already been recognised as glacial/deglacial cycles from detailed studies of the Quaternary. Four orders of sea-level fluctuation are recognised within the Late Neogene, these are of approximately 0.05 Ma., 0.1-0.3 Ma., 2 Ma., and 4 Ma. in duration. The 2 Ma. and 4 Ma. duration cycles are subdivisions of the third order cyclicity recognised by Vail et al. (1991) (referred to here as cyclicity orders 3a and 3b). The 0.1-0.3 Ma. duration cycles are a subset of the fourth order cyclicity recognised Vail et al. (1991), and the 0.05 Ma. Duration cycles are a subset of the 5 th order cyclicity recognised by Vail et al. (1991). 3a, 3b and 4 th order sea level fluctuations are driven by fluctuations in the volume of the Antarctic Ice Sheet. Fifth order sea level fluctuations are also suggested to be at least partially driven by fluctuations in the volume of the Antarctic Ice Sheet. Milankovitch cyclicities in glacioeustasy (<100 Ka., fifth order cyclicity) are prominent in the geologic record at times when there is large scale glaciation (glacialism) of the Antarctic Continent (e.g. for the Pleistocene). Conversely, at times when the Antarctic continent is in a deglaciated state (deglacialism) fourth order cyclicity is more prominent, with Milankovitch cyclicities present at a parasequence level.</p>

Late Neogene Radiolaria from the East Coast Deformed Belt, New Zealand

<p>Within the East Coast Deformed Belt there are a number of Late Neogene sedimentary basins with relatively deep-water sediments which, at places, contain abundant radiolarian skeletons. The region was subject to relatively open ocean circulation patterns during the Neogene which, combined with the input of rhyolitic glass shards, has enhanced the siliceous microfossil preservation. A short review of the silica budget is presented and discussed in relation to the preservation of siliceous microfossils in the New Zealand sequences. Techniques were developed to extract and quantitatively study fossil Radiolaria from some of the relatively barren shelf/slope sediments. One hundred and thirty-eight radiolarian taxa are described, most of which can be assigned at the generic level, but thirty-one of which can not be assigned specific names and may eventually prove to be new species. The radiolarian zonation presented is based on detailed analysis of 155 samples from 26 sections and sites ranging in age from basal Tongaporutuan (early Late Miocene) to middle Nukumaruan (early Pleistocene). Sediments of the Kapitean (uppermost Miocene) were generally deposited in shallow water environments or are missing in unconformities in the East Coast Deformed Belt, consequently the radiolarian zonation is based on very poor data in this time segment. Also upper Opoitian and Waipipian (middle Pliocene) sediments, although at places deposited in relatively deep water, generally lack siliceous tuffs, and radiolarian preservation is poor. Five major radiolarian zones can be recognised: Diartus hughesi Zone, Didymocyrtis sp. A Zone, Didymocyrtis sp. A Zone, Didymocyrtis tetrathalmus tetrathalmus Zone, Lamprocyrtis heteroporos Zone, and Lamprocyclas gamphonycha Zone. In samples with good radiolarian preservation six subzones can be identified. The Diartus hughesi Zone can be divided into the Heliodiscus umbonatum Subzone, Didymocyrtis laticonus Subzone, Heliodiscus asteriscus forma large pores Subzone, and Anthocyrtidium ehrenbergi pliocenica Subzone. Additionally the Didymocyrtis tetrathalmus tetrathalmus Zone can be divided into the Lychnocanium sp. aff. grande Subzone and Lamprocyrtis hannai Subzone. The bioevents that define the zonal boundaries are discussed along with other biostratigraphically useful radiolarian datums. These zones and zubzones are correlated to the foraminiferal zonation which in turn has been related, in part, to the paleomagnetic time scale. Correlation are then made with other radiolarian zonations in the north Pacific, tropics, and southern ocean. Points to emerge from these correlations include the apparent provincialism in the transition from Stichocorys delmontense to Stichocorys peregrine in the tropical Pacific. This transition has been reported to occur during approximately 1.5Ma but in New Zealand occurs over a time segment of at least 5.5Ma. The first appearance of Lamprocyclas gamphonycha appears to be an isochronous datum level in temperate radiolarian faunas of the northern and southern Pacific. The last appearance datum of Diartus hughesi at about 7.5Ma is in good agreement with its level in the tropics. The presence of this taxon in lower Gilbert Antarctic cores suggests either a grossly diachronous event between tropical/temperate areas and the southern ocean or, more probably, a misinterpretation of the paleomagnetic signature from key southern ocean piston cores. If the latter situation is the case then the real age estimates on the "Pre middle Gilbert" southern ocean diatom and silicoflagellate stratigraphies are questionable because they are based on the same key cores. Statistical faunal analysis shows that during the Miocene there was not much change in the radiolarian faunas with time and a major change, probably climatically controlled, took place across the Miocene/Pliocene boundary. Variability in preservation has probably affected the faunas to obscure more precise time variation although post-Miocene faunas indicate that some is present. In conclusion, the Radiolaria, although not as common in the fossil record as the foraminifera, definitely contribute to New Zealand Late Neogene integrated stratigraphy and suggest that our knowledge could be greatly enhanced by the study of other siliceous microfossil groups.</p>

Biogeography of Argylia D. Don (Bignoniaceae): Diversification, Andean Uplift and Niche Conservatism

Andean uplift and the concomitant formation of the Diagonal Arid of South America is expected to have promoted species diversification through range expansions into this novel environment. We evaluate the evolution of Argylia, a genus belonging to the Bignoniaceae family whose oldest fossil record dates back to 49.4 Ma. Today, Argylia is distributed along the Andean Cordillera, from 15°S to 38.5°S and from sea level up to 4,000 m.a.s.l. We ask whether Argylia’s current distribution is a result of a range expansion along the Andes Cordillera (biological corridor) modulated by climatic niche conservatism, considering the timing of Andean uplift (30 Ma – 5 Ma). To answer this question, we reconstructed the phylogenetic relationships of Argylia species, estimated divergence times, estimated the realized climatic niche of the genus, reconstructed the ancestral climatic niche, evaluated its evolution, and finally, performed an ancestral range reconstruction. We found strong evidence for climatic niche conservatism for moisture variables, and an absence of niche conservatism for most of the temperature variables considered. Exceptions were temperature seasonality and winter temperature. Results imply that Argylia had the capacity to adapt to extreme temperature conditions associated with the Andean uplift and the new climatic corridor produced by uplift. Ancestral range reconstruction for the genus showed that Argylia first diversified in a region where subtropical conditions were already established, and that later episodes of diversification were coeval with the of Andean uplift. We detected a second climatic corridor along the coastal range of Chile-Peru, the coastal lomas, which allowed a northward range expansion of Argylia into the hyperarid Atacama Desert. Dating suggests the current distribution and diversity of Argylia would have been reached during the Late Neogene and Pleistocene.