Denudation response of the Mediterranean Alpine Ranges to the Quaternary glacial cycles

2021 ◽  
Author(s):  
Pierre-Henri Blard ◽  
Stéphane Molliex ◽  
Apolline Mariotti ◽  
Julien Charreau ◽  
Gwenaël Jouet ◽  
...  
Keyword(s):  
High Resolution ◽  
Southern Alps ◽  
Special Focus ◽  
Glacial Cycles ◽  
Climatic Fluctuations ◽  
Denudation Rates ◽  
Original Dataset ◽  
Climatic Transition ◽  
The Mediterranean ◽  
Glacier Flow

<p>It is important to better understand how climatic fluctuations modified denudation, in particular during the large amplitude glacial cycles of the Quaternary, not only because denudation is thought to be a long-term climate pacer, but also because available denudation records are contradictory and sometimes underconstrained. To make progress on this question, we present here a compilation of <sup>10</sup>Be-derived denudation rates from 6 boreholes and cores drilled in offshore sediments from two alpine massifs of the Mediterranean Sea: Southern Alps (Var River) and Corsica (Golo River). This original dataset of 60 <sup>10</sup>Be samples from well-dated sedimentary archives documents at high resolution (1 kyr in some sections) the denudation variability over the last 3 million years of the alpine reliefs, with a special focus on the last five 100 kyr glacial cycles. Our new record brings two main results:</p><p>1) At the million years timescale, the appearance of the Quaternary glaciations at the Plio-Pleistocene transition (2.6 Ma) had a negligible impact on the mean <sup>10</sup>Be-derived denudation rates of Mediterranean Alpine reliefs. This observation is in good agreement with other <sup>10</sup>Be-denudation rates records from Asia (Tianshan and Himalaya) that report a limited impact of the Pleistocene climatic transition (Puchol et al., 2017; Charreau et al., 2020; Lenard et al., 2020), but at odds with other regions of the American Cordilleras, where tectonic may have played a role (Stock et al., 2004; Granger and Schaller, 2014).</p><p>2) At the glacial-interglacial cycles timescale, our high resolution <sup>10</sup>Be data over the last 500 kys reveal that glacial maxima enhanced denudation compared to interglacial periods. However, this impact is variable in space and time, different denudation responses being observed between Southern Alps and Corsica. This contrasted behavior appears to be controlled by the velocity of paleoglaciers. Glacier flow being determined by the combined impact of paleoclimate and basin reliefs, this mechanism is responsible for a non-linear response of denudation to glacier fluctuations. This may explain why glaciations had regionally variable impacts on denudation (Mariotti et al., 2021).</p><p><strong>References</strong></p><p>Charreau, J. et al. (2020) Basin Research. doi: 10.1111/bre.12511; Granger, D. E. and Schaller, M. (2014) Elements, doi: 10.2113/gselements.10.5.369; Lenard, S. J. P. et al. (2020) Nature Geoscience, doi: 10.1038/s41561-020-0585-2; Mariotti, A. et al. (2021) Nature Geoscience, doi: 10.1038/s41561-020-00672-2; Puchol, N. et al. (2017) Bulletin of the Geological Society of America, doi: 10.1130/B31475.1; Stock, G. M., et al. (2004) Geology, doi: 10.1130/G20197.1.</p>

scholarly journals Rapid climatic variability in the west Mediterranean during the last 25 000 years from high resolution pollen data

2009 ◽  
Vol 5 (3) ◽  
pp. 503-521 ◽  
Author(s):  
N. Combourieu Nebout ◽  
O. Peyron ◽  
I. Dormoy ◽  
S. Desprat ◽  
C. Beaudouin ◽  
...  
Keyword(s):  
High Resolution ◽  
North Atlantic ◽  
Climate Reconstruction ◽  
Mediterranean Vegetation ◽  
Pollen Record ◽  
Alboran Sea ◽  
Climatic Fluctuations ◽  
The Holocene ◽  
The Mediterranean ◽  
Alborán Sea

Abstract. High-temporal resolution pollen record from the Alboran Sea ODP Site 976, pollen-based quantitative climate reconstruction and biomisation show that changes of Mediterranean vegetation have been clearly modulated by short and long term variability during the last 25 000 years. The reliability of the quantitative climate reconstruction from marine pollen spectra has been tested using 22 marine core-top samples from the Mediterranean. The ODP Site 976 pollen record and climatic reconstruction confirm that Mediterranean environments have a rapid response to the climatic fluctuations during the last Termination. The western Mediterranean vegetation response appears nearly synchronous with North Atlantic variability during the last deglaciation as well as during the Holocene. High-resolution analyses of the ODP Site 976 pollen record show a cooling trend during the Bölling/Allerød period. In addition, this period is marked by two warm episodes bracketing a cooling event that represent the Bölling-Older Dryas-Allerød succession. During the Holocene, recurrent declines of the forest cover over the Alboran Sea borderlands indicate climate events that correlate well with several events of increased Mediterranean dryness observed on the continent and with Mediterranean Sea cooling episodes detected by alkenone-based sea surface temperature reconstructions. These events clearly reflect the response of the Mediterranean vegetation to the North Atlantic Holocene cold events.

Venerid bivalve Venus verrucosa as a high-resolution archive of seawater temperature in the Mediterranean Sea

2021 ◽  
Vol 561 ◽  
pp. 110057
Author(s):  
Hana Uvanović ◽  
Bernd R. Schöne ◽  
Krešimir Markulin ◽  
Ivica Janeković ◽  
Melita Peharda
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Seawater Temperature ◽  
The Mediterranean

Neogene continental denudation and the beryllium conundrum

2021 ◽  
Vol 118 (42) ◽  
pp. e2026456118
Author(s):  
Shilei (李石磊) Li ◽  
Steven L. Goldstein ◽  
Maureen E. Raymo
Keyword(s):  
Fold Increase ◽  
Silicate Weathering ◽  
Late Cenozoic ◽  
Glacial Cycles ◽  
Denudation Rates ◽  
Geological Processes ◽  
Basalt Weathering ◽  
Beryllium Isotopes ◽  
Continental Weathering ◽  
Pyrite Weathering

Reconstructing Cenozoic history of continental silicate weathering is crucial for understanding Earth’s carbon cycle and greenhouse history. The question of whether continental silicate weathering increased during the late Cenozoic, setting the stage for glacial cycles, has remained controversial for decades. Whereas numerous independent proxies of weathering in ocean sediments (e.g., Li, Sr, and Os isotopes) have been interpreted to indicate that the continental silicate weathering rate increased in the late Cenozoic, beryllium isotopes in seawater have stood out as an important exception. Beryllium isotopes have been interpreted to indicate stable continental weathering and/or denudation rates over the last 12 Myr. Here we present a Be cycle model whose results show that variations in the 9Be weathering flux are counterbalanced by near-coastal scavenging while the cosmogenic 10Be flux from the upper atmosphere stays constant. As a result, predicted seawater 10Be/9Be ratios remain nearly constant even when global denudation and Be weathering rates increase by three orders of magnitude. Moreover, 10Be/9Be records allow for up to an 11-fold increase in Be weathering and denudation rates over the late Cenozoic, consistent with estimates from other proxies. The large increase in continental weathering indicated by multiple proxies further suggests that the increased CO2 consumption by continental weathering, driven by mountain-building events, was counterbalanced by other geological processes to prevent a runaway icehouse condition during the late Cenozoic. These processes could include enhanced carbonate dissolution via pyrite weathering, accelerated oxidation of fossil organic carbon, and/or reduced basalt weathering as the climate cooled.

scholarly journals Climate Change Impacts Assessment on Wine-Growing Bioclimatic Transition Areas

Agriculture ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 605
Author(s):  
Alba Piña-Rey ◽  
Estefanía González-Fernández ◽  
María Fernández-González ◽  
Mª. Nieves Lorenzo ◽  
Fco. Javier Rodríguez-Rajo
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
Climate Change Impacts ◽  
Mediterranean Area ◽  
Cultural Practice ◽  
Climatic Conditions ◽  
Study Region ◽  
Bioclimatic Indices ◽  
Northwestern Spain ◽  
The Mediterranean

Viticultural climatic indices were assessed for the evaluation of the meteorological variations in the requirements of wine cultivars. The applied bioclimatic indices have been widely used to provide an initial evaluation of climate change impacts on grapevine and to delineate wine regions and suitable areas for planting around the world. The study was carried out over a period of 16 years (from 2000 to 2015) in five Designation of Origin areas in Northwestern Spain located in the Eurosiberian region, the transition zone between the Eurosiberian and the Mediterranean areas, and in the Mediterranean area. In addition, the high-resolution meteorological dataset “Spain02” was applied to the bioclimatic indices for the period 1950–2095. To further assess the performance of “Spain02”, Taylor diagrams were elaborated for the different bioclimatic indices. A significant trend to an increase of the Winkler, Huglin, Night Cold Index and GSS Indices was detected in the North-western Spain, whereas slight negative trends for BBLI and GSP Indices were observed. To analyze future projections 2061–2095, data from the high-resolution dynamically downscaled daily climate simulations from EURO-CORDEX project were used. To further assess the performance of Spain02, Taylor diagrams were elaborated for the different bioclimatic indices. A trend to an increase of the Winkler, Huglin, Night Cold Index and GSP Indices was detected in Northwestern Spain, whereas slight negative trends for BBLI and GSP Indices were observed. Our results showed that climatic conditions in the study region could variate for the crop in the future, more for Mediterranean than Eurosiberian bioclimatic area. Due to an advance in the phenological events or the vintage data, more alcohol-fortified wines and variations in the acidity level of wines could be expected in Northwestern Spain, these processes being most noticeable in the Mediterranean area. The projections for the BBLI and GSP Indices will induce a decrease in the pressure of the mildew attacks incidence in the areas located at the Eurosiberian region and the nearest transition zones. Projections showed if the trend of temperature increase continues, some cultural practice variations should be conducted in order to preserve the grape cultivation suitability in the studied area.

scholarly journals Climatic effects on rapid chemical and physical denudation rates measured with cosmogenic nuclides in the Ōhau catchment, New Zealand

2021 ◽  
Author(s):  
◽  
Maia Bellingham
Keyword(s):  
Carbon Dioxide ◽  
New Zealand ◽  
Chemical Weathering ◽  
Southern Alps ◽  
Grain Sizes ◽  
Denudation Rates ◽  
Climate Stability ◽  
Mountain Landscapes ◽  
Carbon Dioxide Cycling

<p>Understanding how active mountain landscapes contribute to carbon dioxide cycling and influences on long-term climate stability requires measurement of weathering fluxes from these landscapes. The few measured chemical weathering rates in the Southern Alps are an order of magnitude greater than in the rest of the world. Rapid tectonic uplift coupled with extreme orographic precipitation is driving exceptionally fast chemical and physical denudation. These rates suggest that weathering in landscapes such as the Southern Alps could play a significant role in carbon dioxide cycling. However, the relative importance of climate and tectonics driving these fast rates remains poorly understood.   To address this gap, in situ ¹⁰Be derived catchment-averaged denudation rates were measured in the Ōhau catchment, Canterbury, New Zealand. Denudation rates in the Dobson Valley within the Ōhau catchment, varied from 474 – 7,570 m Myr⁻¹, aside from one sub-catchment in the upper Dobson Valley that had a denudation rate of 12,142 m Myr⁻¹. The Dobson and Hopkins Rivers had denudation rates of 1,660 and 4,400 m Myr⁻¹ respectively, in these catchments. Dobson Valley denudation rates show a moderate correlation with mean annual precipitation (R²=0.459). This correlation supports a similar trend identified at local and regional scales, and at high rates of precipitation this may be an important driver of erosion and weathering.   Sampling of four grain sizes (0.125 to > 8 mm) at one site in the Dobson Valley resulted in variability in ¹⁰Be concentrations up to a factor of 2.5, which may be a result of each grain size recording different erosional processes. These observations demonstrate the importance of assessing potential variability and the need to sample consistent grain sizes across catchments.   Chemical depletion fractions measured within soil pits in the upper Dobson Valley indicate chemical weathering contributes 30% of total denudation, and that physical erosion is driving rapid total denudation. Chemical weathering appears to surpass any proposed weathering speed limit and suggests total weathering may not be limited by weathering kinetics. This research adds to the paucity of research in New Zealand, and for the first time presents ¹⁰Be derived denudation rates from the eastern Southern Alps, with estimates of the long-term weathering flux. High weathering fluxes in the Southern Alps uphold the hypothesis that mountain landscapes play an important role in carbon dioxide cycling and long-term climate stability.</p>

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