Extirpations and extinctions: a plant microfossil-based history of the demise of rainforest and wet sclerophyll communities in the Lake George basin, Southern Tablelands of NSW, south-east Australia

2020 ◽  
Vol 68 (3) ◽  
pp. 208 ◽  
Author(s):  
Mike Macphail ◽  
Brad Pillans ◽  
Geoff Hope ◽  
Dan Clark

Sites recording the extinction or extirpation of tropical–subtropical and cool–cold temperate rainforest genera during the Plio–Pleistocene aridification of Australia are scattered across the continent, with most preserving only partial records from either the Pliocene or Pleistocene. The highland Lake George basin is unique in accumulating sediment over c. 4 Ma although interpretation of the plant microfossil record is complicated by its size (950km2), neotectonic activity and fluctuating water levels. A comparison of this and other sites confirms (1) the extinction of rainforest at Lake George was part of the retreat of Nothofagus-gymnosperm communities across Australia during the Plio–Pleistocene; (2) communities of warm- and cool-adapted rainforest genera growing under moderately warm-wet conditions in the Late Pliocene to Early Pleistocene have no modern analogues; (3) the final extirpation of rainforest taxa at Lake George occurred during the Middle Pleistocene; and (4) the role of local wildfires is unresolved although topography, and, elsewhere, possibly edaphic factors allowed temperate rainforest genera to persist long after these taxa became extinct or extirpated at low elevations across much of eastern Australia. Araucaria, which is now restricted to the subtropics–tropics in Australia, appears to have survived into Middle Pleistocene time at Lake George, although the reason remains unclear.

2020 ◽  
Author(s):  
Gilles Rixhon ◽  
Didier L. Bourlès ◽  
Régis Braucher ◽  
Alexandre Peeters ◽  
Alain Demoulin

<p>Multi-level cave systems record the history of regional river incision in abandoned alluvium-filled phreatic passages which, mimicking fluvial terrace sequences, represent former phases of fluvial base-level stability. In this respect, cosmogenic burial dating of in cave-deposited alluvium (usually via the nuclide pair <sup>26</sup>Al/<sup>10</sup>Be) represents a suitable method to quantify the pace of long-term river incision. Here, we present a dataset of fifteen <sup>26</sup>Al/<sup>10</sup>Be burial ages measured in fluvial pebbles washed into a multi-level cave system developed in Devonian limestone of the uplifted Ardenne massif (eastern Belgium). The large and well-documented Chawresse system is located along the lower Ourthe valley (i.e. the main Ardennian tributary of the Meuse river) and spans altogether an elevation difference exceeding 120 m.</p><p>The depleted <sup>26</sup>Al/<sup>10</sup>Be ratios measured in four individual caves show two main outcomes. Firstly, computed burial ages ranging from ~0.2 to 3.3 Ma allows highlighting an acceleration by almost one order of magnitude of the incision rates during the first half of the Middle Pleistocene (from ~25 to ~160 m/Ma). Secondly, according to the relative elevation above the present-day floodplain of the sampled material in the Manants cave (<35 m), the four internally-consistent Early Pleistocene burial ages highlight an “anomalous” old speleogenesis in the framework of a gradual base-level lowering. They instead point to intra-karsting reworking of the sampled material in the topographically complex Manants cave. This in turn suggests an independent, long-lasting speleogenetic evolution of this specific cave, which differs from the <em>per descensum</em> model of speleogenesis generally acknowledged for the regional multi-level cave systems and their abandoned phreatic galleries. In addition to its classical use for inferring long-term incision rates, cosmogenic burial dating can thus contribute to better understand specific and complex speleogenetic evolution.</p>


Zootaxa ◽  
2017 ◽  
Vol 4237 (2) ◽  
pp. 393 ◽  
Author(s):  
ALBERTO COLLARETA ◽  
CURTIS W. MAREAN ◽  
ANTONIETA JERARDINO ◽  
MARK BOSSELAERS

The late Middle Pleistocene cave site of Pinnacle Point 13B (PP13B, South Africa) has provided the archaeologically oldest evidences yet known of human consumption of marine resources. Among the marine invertebrates recognised at PP13B, an isolated whale barnacle compartment was tentatively determined as Coronula diadema and regarded as indirect evidence of human consumption of a baleen whale (likely Megaptera novaeangliae). In this paper we redetermine this coronulid specimen as Cetopirus complanatus. This record significantly extends the fossil history of C. complanatus back by about 150 ky, thus partially bridging the occurrence of Cetopirus fragilis in the early Pleistocene to the latest Quaternary record of C. complanatus. Since C. complanatus is currently known as a highly specific phoront of right whales (Eubalaena spp.), we propose that the late Middle Pleistocene human groups that inhabited PP13B fed on a stranded southern right whale. Therefore, the whale barnacle from PP13B suggests the persistence of a southern right whale population off South Africa during the predominantly glacial MIS 6, thus evoking the continuity of cetacean migrations and antitropical distribution during that global cold phase. Interestingly, the most ancient evidence of humans feeding on a whale involves Eubalaena, historically the most exploited cetacean genus, and currently still seriously threatened with extinction due to human impact. 


2013 ◽  
Vol 184 (1-2) ◽  
pp. 21-34 ◽  
Author(s):  
Jean-Marc Lardeaux ◽  
Philippe Münch ◽  
Michel Corsini ◽  
Jean-Jacques Cornée ◽  
Chrystèle Verati ◽  
...  

Abstract In this paper we present and discuss new investigations performed on both the magmatic basement and the sedimentary formations of La Désirade. We report structural and sedimentary evidences for several episodes of deformation and displacement occurring prior to the present day tectonics. The main faults, respectively N130 ± 10°, N040 ± 10° and N090 ± 10°, previously considered as marker of the current tectonic regime corresponds to reactivated tectonic structures developed first during late Cretaceous compression and second during Pliocene to early Pleistocene extension. We demonstrate also the importance of late Pliocene-early Pleistocene and middle-late Pleistocene vertical movements in this part of the Lesser Antilles fore-arc as well as the role of compressive tectonics in the over thickened character of the arc basement in the Guadeloupe archipelago.


2020 ◽  
Vol 12 (3) ◽  
pp. 461-471
Author(s):  
Valeriy DOTSENKO ◽  
◽  
Ibragim KERIMOV ◽  

The Greater Caucasus experienced repeated glaciation during the Quaternary (early, middle, upper Pleistocene, late Glacial, and late Holocene), which occurred under changing climatic conditions and differentiated tectonic movements. These glaciations, of course, are associated with changes in terrain, the formation of new deposits, transgressions and regressions of the Caspian Sea, changes in vegetation and soil types, so the problem of glaciation affects all earth Sciences to varying degrees. The study of Quaternary glaciation, especially Holocene glaciation, is currently relevant for understanding climate change. Against the background of significant climate fluctuations within the epochs of glaciation, there are smaller cooling phases that cause the temporary onset of glaciers. Short-term climate fluctuations are manifested in oscillations – minor fluctuations in the languages of glaciers. All this indicates that the climate undergoes significant changes in a short time, which are reflected in the morphosculpture of the terrain, the latest deposits and modern precipitation. Glaciation of the Greater Caucasus in the Prikazbeksky region reached its maximum in the middle Pleistocene,when glaciers went far into the Ossetian basin. All these traces have been preserved due to the lower capacity of the Chanty-Argun glacier and its fluvioglacial flow, which developed during the late Pleistocene epoch. Volcanic activity, especially active in the late Pliocene and continuing up to the present time, is associated with the late horn stage of development of the Caucasus. The formation of the Rukhs-Dzuar molass formation more than 2 km thick in the late Pleistocene in the Ossetian basin of the Tersky-Caspian flexure is associated with the activity of volcanoes in the Kazbek volcanic region. In the early Pleistocene, volcanic activity on the BC decreased significantly. The most intense outbreak of volcanism in the Kazbek and Elbrus volcanic regions occurred at the beginning of the late Pleistocene, which roughly coincided with the maximum phase of the late Pleistocene (Bezengian) glaciation. Then, in the second half of the late Pleistocene, volcanic activity was manifested on the mount Kazbek. The last outbreak of volcanic activity occurred in the Holocene no more than 2-3 thousand years ago. Fresh lavas are available on Elbrus, Kazbek, in the Terek valley near villages. Sioni and on the Kel volcanic plateau. Fumarolic activity still continues on Elbrus. Thus, in the Kazbek region, eruptions occurred from the late Pliocene to the late Holocene inclusive. Keywords: Pleistocene, Holocene, glaciation stages, nival-glacial processes, causes of glaciations, climate change, anthropogenic factors, natural factors, Earth degassing, magmatogenic degassing branch, seismotectonic degassing branch, greenhouse gases, newest geodynamics, volcanism, mud regimes, volcanism, methane hydrates, land degradation, water reclamation.


Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 65
Author(s):  
Ilaria Isola ◽  
Francesco Mazzarini ◽  
Giancarlo Molli ◽  
Leonardo Piccini ◽  
Elena Zanella ◽  
...  

A sedimentary sequence of fluvial deposits preserved in the Corchia Cave (Alpi Apuane) provides new chronological constraints for the evolution of the cave system and the timing and rate of uplift of this sector of the Alpi Apuane since the late Pliocene. Supported by magnetostratigraphic analysis performed on fine-grained fluvial deposits, and by radiometric dating of speleothems, we suggest that the deposition of fluvial sediments occurred between ~1.6–1.2 Ma. This implies that the host volume of rock was already located close to the local base level, adding key information about the recent tectonic evolution of the Alpi Apuane. A few before ~1 Ma, an erosive phase occurred due to the base-level lowering, followed by continuous speleothem deposition since at least 0.97 Ma. From that time, Monte Corchia uplifted at a maximum rate of ~0.5 mm/year, which is consistent with isostatic uplift mainly driven by erosional unloading. The petrographical study of the fluvial deposits highlights the presence of material derived from the erosion of rocks that today are absent in the cave’s catchment area, suggesting a different surface morphology during the Early Pleistocene. This study highlights the potential of cave sediments as archives for reconstructing the uplift history of mountain ranges.


2017 ◽  
Vol 91 (6) ◽  
pp. 1258-1271 ◽  
Author(s):  
Lorenzo Rook ◽  
Saverio Bartolini Lucenti ◽  
Maia Bukhsianidze ◽  
David Lordkipanidze

AbstractUnlike the Asian and North American Pliocene record, fossil occurrences of Canidae in Europe (and Africa) are uncommon and fragmentary. The revision of canid material from the late Pliocene site of Kvabebi (eastern Georgia) revealed the contemporaneous occurrence of three different taxa: (1)Nyctereutes megamastoides(a derived species of the Eurasian Pliocene raccoon dog-like canids); (2)Vulpescf.V.alopecoides(representing the first occurrence of a member of the vulpine taxonV.alopecoides, a species that was the most widespread fox in the early Pleistocene in western Europe); and (3)Eucyonsp. The latter occurrence at Kvabebi completes our knowledge of the late Pliocene evolutionary history of the latest representatives of the genus in Western Europe and Central Asia. Our revision of Kvabebi canids registers a previously undocumented case of established niche partitioning among early Pliocene sympatric Canidae.


2020 ◽  
Author(s):  
Vivi Kathrine Pedersen ◽  
Nicolaj Krog Larsen ◽  
David Lundbek Egholm

<p>The timing and extent of early glaciations in Greenland, and their co-evolution with the underlying landscape remain elusive. In this study, we explore the timing of fjord erosion in Northeast and North Greenland between Scoresby Sund (70°N) and Independence Fjord (82°N). By determining the timing of fjord formation, we can improve our understanding of the early history of the Greenland Ice Sheet in these regions.</p><p>We use the concept of geophysical relief to estimate fjord erosion and calculate the subsequent flexural isostatic response to erosional unloading. The timing of erosion and isostatic uplift is constrained by marine sediments of late Pliocene-early Pleistocene age that are now exposed on land between ~24 and 230 m a.s.l.</p><p>We find that the northern Independence Fjord system must have formed by glacial erosion at average rates of ~0.5-1 mm/yr since ~2.5 Ma, in order to explain the current elevation of the marine Kap København Formation by erosion-induced isostatic uplift. In contrast, fjord formation in the outer parts of southward Scoresby Sund commenced before the Pleistocene, most likely in late Miocene, and continued throughout the Pleistocene by fjord formation progressing inland. Our results suggest that the inception of the Greenland Ice Sheet began in the central parts of Northeast Greenland before the Pleistocene and spread to North Greenland only at the onset of the Pleistocene.  </p>


2019 ◽  
Vol 75 (3-4) ◽  
pp. 343-358
Author(s):  
Elena Syromyatnikova ◽  
Alexey Tesakov ◽  
Serdar Mayda ◽  
Tanju Kaya ◽  
Gerçek Saraç

Abstract Small fossil vertebrates from several Pliocene and Pleistocene localities in Central Anatolia (Turkey) are reviewed. Data on small mammals represent assemblages from the early Pliocene (MN 14: Nasrettinhoca 1, 2 and Hamamkarahisar A, B), and late Pliocene (MN 16: Hoyhoytepe 1, 2, 3 and Mercan 1); Early Pleistocene (MN 17: Mercan 2), and Middle Pleistocene (MQ 1/MQ 2: Yenişarbademli). The biochronology related characters of arvicolines Promimomys, Mimomys, Microtus, Lagurus and Clethrionomys are briefly discussed. Data on the systematics of fossil amphibians and reptiles is also described from these localities. The early Pliocene (MN 14) assemblages significantly add to knowledge on the herpetofaunal composition of this stratigraphic level, which until now was poorly characterized in Turkey. Remains of Pelobatidae, Bufonidae, Ranidae, Amphisbaenia and Natricinae are reported for the first time from the MN 14 biozone of Turkey. Palaeobatrachus from Mercan 1 extends the temporal range of this group in the Eastern Mediterranean into the late Pliocene. The described remains of amphibians and reptiles from Turkey span a considerable stratigraphic range from the early Pliocene to the Middle Pleistocene (time interval of about 5 Ma) and partly fill a gap in the palaeoherpetofaunal record of the Eastern Mediterranean.


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