scholarly journals The Campanian Ignimbrite (Y5) tephra at Crvena Stijena Rockshelter, Montenegro

2011 ◽  
Vol 75 (3) ◽  
pp. 683-696 ◽  
Author(s):  
Mike W. Morley ◽  
Jamie C. Woodward
Keyword(s):  
Land Surface ◽  
Middle Pleistocene ◽  
Geochemical Data ◽  
Tephra Layer ◽  
Upper Palaeolithic ◽  
Campanian Ignimbrite ◽  
Volcanic Province ◽  
Particle Size Data ◽  
Sediment Records ◽  
Size Data

AbstractClearly defined distal tephras are rare in rockshelter sediment records. Crvena Stijena, a Palaeolithic site in Montenegro, contains one of the longest (> 20 m) rockshelter sediment records in Europe with deposits ranging in age from Middle Pleistocene to mid-Holocene. A distinctive tephra is clearly exposed within the well stratified record approximately 6.5 m below the present land surface. We present geochemical data to confirm that this tephra is a distal equivalent of the Campanian Ignimbrite deposits and a product of the largest Late Pleistocene eruption in Europe. Originating in the Campanian volcanic province of southwest Italy, this tephra has been independently dated to 39.3 ka. It is a highly significant chronostratigraphic marker for southern Europe. Macrostratigraphic and microstratigraphic observations, allied with detailed particle size data, show that the tephra layer is in a primary depositional context and was transported into the rockshelter by aeolian processes. This site is unique because the tephra forms an abrupt boundary between the Middle and Upper Palaeolithic records. Before they can be used as chronostratigraphic markers in rockshelter and cave-mouth environments, it is essential to establish the stratigraphic integrity of distal tephras and the mechanisms and pathways involved in their transport and deposition.

scholarly journals Pedotransfer functions for converting laser diffraction particle-size data to conventional values

2017 ◽  
Vol 68 (5) ◽  
pp. 769-782 ◽  
Author(s):  
A. Makó ◽  
G. Tóth ◽  
M. Weynants ◽  
K. Rajkai ◽  
T. Hermann ◽  
...  
Keyword(s):  
Particle Size ◽  
Laser Diffraction ◽  
Pedotransfer Functions ◽  
Particle Size Data ◽  
Size Data

scholarly journals Earliest land plants created modern levels of atmospheric oxygen

2016 ◽  
Vol 113 (35) ◽  
pp. 9704-9709 ◽  
Author(s):  
Timothy M. Lenton ◽  
Tais W. Dahl ◽  
Stuart J. Daines ◽  
Benjamin J. W. Mills ◽  
Kazumi Ozaki ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Land Surface ◽  
Atmospheric Oxygen ◽  
Geochemical Data ◽  
Regulatory Regime ◽  
Carbon Burial ◽  
C:P Ratio ◽  
Marine Biomass ◽  
Organic Carbon Burial

The progressive oxygenation of the Earth’s atmosphere was pivotal to the evolution of life, but the puzzle of when and how atmospheric oxygen (O2) first approached modern levels (∼21%) remains unresolved. Redox proxy data indicate the deep oceans were oxygenated during 435–392 Ma, and the appearance of fossil charcoal indicates O2 >15–17% by 420–400 Ma. However, existing models have failed to predict oxygenation at this time. Here we show that the earliest plants, which colonized the land surface from ∼470 Ma onward, were responsible for this mid-Paleozoic oxygenation event, through greatly increasing global organic carbon burial—the net long-term source of O2. We use a trait-based ecophysiological model to predict that cryptogamic vegetation cover could have achieved ∼30% of today’s global terrestrial net primary productivity by ∼445 Ma. Data from modern bryophytes suggests this plentiful early plant material had a much higher molar C:P ratio (∼2,000) than marine biomass (∼100), such that a given weathering flux of phosphorus could support more organic carbon burial. Furthermore, recent experiments suggest that early plants selectively increased the flux of phosphorus (relative to alkalinity) weathered from rocks. Combining these effects in a model of long-term biogeochemical cycling, we reproduce a sustained +2‰ increase in the carbonate carbon isotope (δ13C) record by ∼445 Ma, and predict a corresponding rise in O2 to present levels by 420–400 Ma, consistent with geochemical data. This oxygen rise represents a permanent shift in regulatory regime to one where fire-mediated negative feedbacks stabilize high O2 levels.

scholarly journals Estimation of spatial covariance of log conductivity from particle size data

2014 ◽  
Vol 50 (6) ◽  
pp. 5298-5308 ◽  
Author(s):  
Monica Riva ◽  
Xavier Sanchez-Vila ◽  
Alberto Guadagnini
Keyword(s):  
Particle Size ◽  
Spatial Covariance ◽  
Particle Size Data ◽  
Size Data

The Campanian Ignimbrite/Y5 tephra layer – A regional stratigraphic marker for Isotope Stage 3 deposits in the Lower Danube region, Romania

2013 ◽  
Vol 293 ◽  
pp. 22-33 ◽  
Author(s):  
Daniel Veres ◽  
Christine S. Lane ◽  
Alida Timar-Gabor ◽  
Ulrich Hambach ◽  
Daniela Constantin ◽  
...  
Keyword(s):  
Tephra Layer ◽  
Campanian Ignimbrite ◽  
Danube Region

scholarly journals Tephrostratigraphy and tephrochronology of lakes Ohrid and Prespa, Balkans

2010 ◽  
Vol 7 (3) ◽  
pp. 3931-3967 ◽  
Author(s):  
R. Sulpizio ◽  
G. Zanchetta ◽  
M. D'Orazio ◽  
H. Vogel ◽  
B. Wagner
Keyword(s):  
Southern Italy ◽  
Mediterranean Area ◽  
Mount Etna ◽  
Middle Pleistocene ◽  
Tephra Layer ◽  
Lake Ohrid ◽  
Central Mediterranean ◽  
The Balkans ◽  
Tephra Layers ◽  
First Time

Abstract. Four cores from Balkans lakes Ohrid and Prespa were studied for recognition of tephra layers and cryptotephras, and the results presented along with the review of data from other two already published cores from Lake Ohrid. The six cores provide a previously unrealised tephrostratigraphic framework of the two lakes, and supply the first detailed tephrochronologic profile (composite) for the Balkans, which spans from the end of the Middle Pleistocene to the end of the Ancient Age (AD 472). A total of 12 tephra layers and cryptotephras were recognised in the cores. One is of Middle Pleistocene age (131 ky) and correlated to the marine tephra layer P-11 from Pantelleria Island. Eight volcanic layers are Upper Pleistocene in age, and encompass the period between ca. 107 ky and ca. 31 ky. This interval contains some of the main regional volcanic markers of the Central Mediterranean area, including X-6, X-5, Y-5 and Y-3 tephra layers. The other layers of this interval have been related to the marine tephra layers C20, Y-6 and C10, while one was for the first time recognised in distal areas and correlated to the Taurano eruption of probable Vesuvian origin. Three cryptotephras were of Holocene age. Two of which have been correlated to Mercato and AD 472 eruptions of Somma-Vesuvius, while the third has been correlated to the FL eruption from Mount Etna. These recognitions provide a link of the Ohrid and Prespa lacustrine successions to other archives of the Central Mediterranean area, like South Adriatic, Ionian, and South Tyrrhenian Seas, lakes of Southern Italy (Lago Grande di Monticchio, Pantano di San Gregorio Magno and Lago di Pergusa) and Balkans (Lake Shkodra).

scholarly journals Volcanology and inflation structures of an extensive basaltic lava flow in the Payenia Volcanic Province, extra-Andean back arc of Argentina

2019 ◽  
Vol 46 (2) ◽  
pp. 279 ◽  
Author(s):  
Mauro Ignacio Bernardi ◽  
Gustavo Walter Bertotto ◽  
Alexis Daniel Ponce ◽  
Yuji Orihashi ◽  
Hirochika Sumino
Keyword(s):  
Lava Flow ◽  
Liquid Core ◽  
Internal Flow ◽  
Middle Pleistocene ◽  
High Concentration ◽  
Volcanic Province ◽  
Low Viscosity ◽  
Effusion Rates ◽  
Flow Pathways ◽  
P Type

The El Puesto lava flow is located in the Payenia Volcanic Province (central-western Argentina), has a length of 70 km and is Middle Pleistocene in age (0.200±0.027 Ma). The flow shows a P-type pahoehoe structure and exhibits several inflation structures, mainly tumuli and also inflation ridges and lava rises. Lava rise pits and radial or annular clefts are common features associated with inflation structures. The gentle slope on which the flow moved (≈0.5°) allowed the lateral coalescence of lobes at the flow front and the development of an external rigid crust that insulated the liquid core. Lava tunnels are frequent and the lava tunnel named “Cueva de Halada” which is located at its medium portion is the best example of a drainage master tube which formed from the cooling of the crust around a stable inflated flow. Tumuli alignments and long inflation ridges reveal the existence of larger tunnels within the flow. Inflation structures may occur in high concentration belts that converge on a single main belt which is assigned to an anastomosed network of internal flow pathways within the main lava body. The development of inflation structures and lava tunnels require low to moderate effusion rates. An average lava supply rate of 1.8x10-4 m3/s and an inflation time of about 15 days were estimated for an average tumulus of this flow. A high and sustained supply of low viscosity lava (η’=1550 - 483 Pa s) was inferred that initially generated a sheet flow of great areal extension. The reduction in effusion rates could then allowed the development of tunnels that carried lava to the distal fronts, generating localized inflation phenomena throughout the lava flow.

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