Vegetation, sea-level, and climate changes during the Messinian salinity crisis

2012 ◽  
Vol 125 (3-4) ◽  
pp. 432-444 ◽  
Author(s):  
G. Jimenez-Moreno ◽  
J. N. Perez-Asensio ◽  
J. C. Larrasoana ◽  
J. Aguirre ◽  
J. Civis ◽  
...  
Keyword(s):  
Sea Level ◽  
Climate Changes ◽  
Messinian Salinity Crisis

Consequences of sea level and climate changes on the morphodynamics of a tropical coastal lagoon during Holocene: An evolutionary model

2014 ◽  
Vol 333 ◽  
pp. 156-172 ◽  
Author(s):  
D. Padmalal ◽  
K.P.N. Kumaran ◽  
K.M. Nair ◽  
Ruta B. Limaye ◽  
S. Vishnu Mohan ◽  
...  
Keyword(s):  
Sea Level ◽  
Coastal Lagoon ◽  
Climate Changes ◽  
Evolutionary Model ◽  
Tropical Coastal Lagoon

Middle to late-Holocene decreased fluvial aggradation and widespread peat initiation in the Ishikari lowland (northern Japan)

The Holocene ◽  
2016 ◽  
Vol 26 (12) ◽  
pp. 1924-1938 ◽  
Author(s):  
Yuji Ishii ◽  
Kazuaki Hori ◽  
Arata Momohara ◽  
Toshimichi Nakanishi ◽  
Wan Hong
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Climate Changes ◽  
Asian Summer Monsoon ◽  
Sedimentary Environment ◽  
New Approach ◽  
Sea Level Fluctuations ◽  
Asian Summer ◽  
Fluvial Sedimentation ◽  
Northern Japan

This study investigated the influence of sea-level and climate changes on the decreased fluvial aggradation and subsequent widespread peat initiation in the middle to late-Holocene in the Ishikari lowland, which is a coastal floodplain formed in response to the postglacial sea-level change. By introducing a new approach to separately evaluate the rates of organic and clastic sediment input, we demonstrated that the peat began to form when the fluvial sedimentation rate was significantly decreased (less than 0.6 mm/yr), while plant macrofossil analysis suggested that lowering of water level is also important to the peat initiation. Such changes in sedimentary environment may be associated with the abrupt abandonment of crevasse splays. The concentrated ages of the peat initiation around 5600–5000, 4600–4300, and 4100–3600 cal. BP suggest that an allogenic control promoted the abandonment of crevasse splays, and different onset ages can be explained by different fluvial responses of the Ishikari River and its tributaries. The abandonment of crevasse splays could result from sea-level fall or decreased precipitation. While submillennial sea-level fluctuations coincident with the peat initiation have not been reported in coastal lowlands of Japan, the close comparison of the onset ages and decreased precipitation recorded in a stalagmite from China, which represents the strength of the East Asian summer monsoon (EASM), suggests that decrease in precipitation led to the abandonment of crevasse splays. Our results may indicate that similar fluvial responses might be common in other coastal floodplains affected by the EASM.

scholarly journals Geomorphic response to sea level and climate changes during Late Quaternary in a humid tropical coastline: Terrain evolution model from Southwest India

PLoS ONE ◽  
2017 ◽  
Vol 12 (5) ◽  
pp. e0176775 ◽  
Author(s):  
Maya K. ◽  
Vishnu Mohan S. ◽  
Ruta B. Limaye ◽  
Damodaran Padmalal ◽  
Navnith K. P. Kumaran
Keyword(s):  
Sea Level ◽  
Climate Changes ◽  
Late Quaternary ◽  
Evolution Model ◽  
Geomorphic Response ◽  
Southwest India

scholarly journals Climate change in the recent geological past and the near future. Predicting its impacts: a Review

2019 ◽  
Vol 55 (1) ◽  
pp. 260
Author(s):  
Constantinos Perisoratis
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Climatic Change ◽  
Sea Level ◽  
Scientific Community ◽  
Climate Changes ◽  
Late Quaternary ◽  
The Earth ◽  
Geological Past ◽  
Near Future

The climate changes are necessarily related to the increase of the Earth’s temperature, resulting in a sea level rise. Such continuous events, were taking place with minor and greater intensity, during the alternation of warm and cool periods in the Earth during the Late Quaternary and the Holocene periods. However, a particularly significant awareness has taken place in the scientific community, and consequently in the greater public, in the last decades: that a climatic change will take place soon, or it is on-going, and that therefore it is important to undertake drastic actions. However, such a climatic change has not been recorded yet, and hence the necessary actions are not required, for the time being.

scholarly journals Graptolite dynamics in Silurian and Devonian time

1987 ◽  
Vol 35 ◽  
pp. 149-159
Author(s):  
T. N. Koren'
Keyword(s):  
Environmental Factors ◽  
Sea Level ◽  
Comparative Studies ◽  
Climate Changes ◽  
Environmental Changes ◽  
Time Intervals ◽  
Early Devonian ◽  
Carbonate Sedimentation ◽  
Reference Sections ◽  
Devonian Age

On the basis of biostratigraphic data known at present some preliminary attempts are made to evaluate graptolite dynamics, that is changes in graptolite diversity in time and space within pelagic fades of Si­lurian and Early Devonian age. For the comparative studies of diversity fluctuations versus some major environmental changes a standard graptolite zonation is used. Several critical and more or less well stu­died stratigraphical intervals are chosen; among them the Ordovician/Silurian, Sheinwoodian/Gorstian and Gorstian/Ludfordian boundary beds. For each level the most complete reference sections are analy­zed. Special attention is given to the graptolite extinction, specification and radiation events within these time intervals. They might have been partly connected with or influenced by the environmental factors as a result of eustatic sea-level and climate changes, alteration of anoxic conditions, migration of carbonate sedimentation in pelagic direction, and other globally detectable events. The graptolite evolution during the time of monograptid existence can be subdivided into three phases using the comparison of the ampli­tude of the extinction-origination events and repeatability of the synphasic cycles.

scholarly journals INFLUENCE OF THE PALEOCLIMATIC RECONSTRUCTIONS UNCERTAINTY ON THE SUBMARINE PERMAFROST DYNAMICS

2019 ◽  
Vol 4 (1) ◽  
pp. 99-105
Author(s):  
Valentina Malakhova ◽  
Alexey Eliseev
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Air Temperature ◽  
Climate Changes ◽  
Arctic Shelf ◽  
The Arctic ◽  
Time Intervals ◽  
Ocean Level ◽  
Subsea Permafrost ◽  
Uncertainty Coefficient

The estimates of the subsea permafrost sensitivity to the uncertainty of paleoclimatic reconstructions of air temperature and ocean level have been obtained. This was done by using the model for thermophysical processes in the subsea sediments and the scenario for climate changes at the Arctic shelf for the last 400 kyr. This model was forced by four time series of temperature at the sediment top, by using different combinations of air temperature and sea level. The uncertainty coefficient of the response of the permafrost base depth is less than 0,3, with the exception of isolated time intervals and / or the deepest areas of the shelf.

The Ardèche endokarstic responses to the eustatic variations resulting from the Messinian salinity crisis

2006 ◽  
Vol 177 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Ludovic Mocochain ◽  
Georges Clauzon ◽  
Jean-Yves Bigot
Keyword(s):  
Sea Level Rise ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Carbonate Platform ◽  
Messinian Salinity Crisis ◽  
Base Level ◽  
Accommodation Space ◽  
Fan Delta ◽  
Delta Progradation ◽  
The Mediterranean

Abstract The Messinian salinity crisis is typically recorded by evaporites in the abyssal plains of the Mediterranean Sea and by canyons incised into the Mediterranean margins and their hinterlands. However, the impacts of crisis on geomorphology and surface dynamics lasted, until canyons were filled by sediments in the Pliocene (fig. 2). In the mid-Rhône valley, the Ardeche Cretaceous carbonate platform is incised over 600 m by the Rhône Messinian canyon. The canyon thalweg is located – 236 m bsl (below sea level) in the borehole of Pierrelatte [Demarcq, 1960; fig. 1]. During the Pliocene, this canyon was flooded as a ria and infilled by a Gilbert type fan delta [Clauzon and Rubino, 1992; Clauzon et al., 1995]. The whole Messinian-Pliocene third order cycle [Haq et al., 1987] generated four benchmark levels. The first two are [Clauzon, 1996]: (i) The pre-evaporitic abandonment surface which is mapped around the belvedere of Saint-Restitut (fig. 1). This surface is synchronous [Clauzon, 1996] of the crisis onset (5.95 Ma) [Gautier et al., 1994; Krigjsman et al., 1999] and, consequently, is an isochronous benchmark. (ii) The Messinian erosional surface is also an isochronous benchmark due to the fast flooding [Blanc, 2002] of the Rhône canyon, becoming a ria at 5.32 Ma [Hilgen and Langereis, 1988]. These surfaces are the result of endoreic Mediterranean sea level fall more than a thousand meters below the Atlantic Ocean. A huge accommodation space (up to more than 1000 m) was created as sea-level rose up to 80 m above its present-day level (asl) during the Pliocene highstand of cycle TB 3.4 (from 5.32 to 3.8 Ma). During the Lower Pliocene this accommodation space was filled by a Gilbert fan delta. This history yields two other benchmark levels: (i) the marine/non marine Pliocene transition which is an heterochronous surface produced by the Gilbert delta progradation. This surface recorded the Pliocene highstand sea level; (ii) the Pliocene abandonment surface at the top of the Gilbert delta continental wedge. Close to the Rhône-Ardeche confluence, the present day elevations of the four reference levels are (evolution of base-level synthesized in fig. 4): (1) 312 m asl, (2) 236 m bsl, (3) 130 m asl, (4) 190 m asl. The Ardèche carbonate platform underwent karstification both surficial and at depth. The endokarst is characterized by numerous cavities organised in networks. Saint-Marcel Cave is one of those networks providing the most complete record (fig. 5). It opens out on the northern side of the Ardeche canyon at an altitude of 100 m. It is made up by three superposed levels extending over 45 km in length. The lower level (1) is flooded and functionnal. It extends beneath the Ardeche thalweg down to the depth of 10 m bsl reached by divers. The observations collected in the galleries lead us to the conclusion that the karst originated in the vadose area [Brunet, 2000]. The coeval base-level was necessarily below those galleries. The two other levels (middle (2) and upper (3)) are today abandoned and perched. The middle level is about 115 m asl and the upper one is about 185 m asl. They are horizontal and have morphologies specific to the phreatic and temporary phreatic zone of the karst (fig. 6). In literature, the terracing of the Saint-Marcel Cave had been systematically interpreted as the result of the lowering by steps of the Ardeche base-level [Guérin, 1973; Blanc, 1995; Gombert, 1988; Debard, 1997]. In this interpretation, each deepening phase of the base level induces the genesis of the gravitary shaft and the abandonment of the previous horizontal level. The next stillstand of base level leads to the elaboration of a new horizontal level (fig. 7). This explanation is valid for most of Quaternary karsts, that are related to glacioeustatic falls of sea-level. However our study on the Saint-Marcel Cave contests this interpretation because all the shafts show an upward digging dynamism and no hint of vadose sections. The same “per ascensum” hydrodynamism was prevailing during the development of the whole network (figs. 8 and 9). We interpret the development of the Ardeche endokarst as related to the eustatic Messinian-Pliocene cycle TB 3.4/3.5 recorded by the Rhône river. The diving investigations in the flooded part of the Saint-Marcel Cave and also in the vauclusian springs of Bourg-Saint-Andeol reached - 154 m bsl. Those depths are compatible only with the incision of the Messinian Rhône canyon at the same altitude (−236 m bsl). The Saint-Marcel lower level would have develop at that time. The ascending shaping of levels 2 and 3 is thus likely to have formed during the ensuing sea-level rise and highstand during the Pliocene, in mainly two steps: (i) the ria stage controlled by the Mediterranean sea level rise and stillstand; (ii) the rhodanian Gilbert delta progradation, that controlled the genesis of the upper level (fig. 10).

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