The Holocene drowned reef of Les Saintes plateau as witness of a long-term tectonic subsidence along the Lesser Antilles volcanic arc in Guadeloupe

Abstract Geodetic measurements reveal modern rates of tectonic deformation along subduction zones, but the kinematics of long-term deformation are typically poorly constrained. We explore the use of submarine coral reefs as a record of long-term coastal vertical motion in order to determine deformation rate and discuss its origins. The Lesser Antilles arc results from the subduction of the American plates beneath the Caribbean plate and undergoes regional vertical deformation. Uplifted reefs along forearc islands are markers of the interplay between tectonics and sea-level variations since the late Pleistocene. We compared results from a numerical model of reef-island profile development to high-resolution marine geophysical measurements of Les Saintes reef plateau (Guadeloupe, French West Indies), a ∼20-km-wide, 250-m-thick submerged platform that lies at 45 m below sea level along the volcanic arc, to constrain its vertical deformation history. Models explore different scenarios over wide parameter domains including start time, basement morphology, sea level variations, reef growth rate, subaerial erosion rate, and vertical motion history. The major features of the plateau (its depth, internal structure, unusual double-barrier) is only reproduced in a context of subsidence, with a constant rate of −0.3 to −0.45 mm/yr since the late Pleistocene, or in a context of increasing subsidence, presently of ∼–0.2 mm/yr. Discussed in the framework of the forearc vertical deformation history, this result indicates subsidence is promoted by local faulting, volcanic, and deep subduction processes. Coseismic deformation accumulation could be a mechanism by which deformation builds up in the long-term. We show that subduction can drive long-term subsidence of a volcanic arc, and demonstrate that submarine reefs are powerful markers of long-term vertical motion.

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A quantitative synthesis of Holocene vegetation change in Nigeria (Western Africa)

The Holocene ◽

10.1177/09596836211033198 ◽

2021 ◽

pp. 095968362110331

Author(s):

Matthew Adesanya Adeleye ◽

Simon Edward Connor ◽

Simon Graeme Haberle

Keyword(s):

Vegetation Change ◽

Climatic Changes ◽

The Holocene ◽

Continental Scale ◽

Western Africa ◽

Chord Distance ◽

Quantitative Synthesis ◽

Climatic Regime ◽

Pollen Records

Understanding long-term (centennial–millennial scale) ecosystem stability and dynamics are key to sustainable management and conservation of ecosystem processes under the currently changing climate. Fossil pollen records offer the possibility to investigate long-term changes in vegetation composition and diversity on regional and continental scales. Such studies have been conducted in temperate systems, but are underrepresented in the tropics, especially in Africa. This study attempts to synthesize pollen records from Nigeria (tropical western Africa) and nearby regions to quantitatively assess Holocene regional vegetation changes (turnover) and stability under different climatic regimes for the first time. We use the squared chord distance metric (SCD) to assess centennial-scale vegetation turnover in pollen records. Results suggest vegetation in most parts of Nigeria experienced low turnover under a wetter climatic regime (African Humid Period), especially between ~8000 and 5000 cal year BP. In contrast, vegetation turnover increased significantly under the drier climatic regime of the late-Holocene (between ~5000 cal year BP and present), reflecting the imp role of moisture changes in tropical west African vegetation dynamics during the Holocene. Our results are consistent with records of vegetation and climatic changes in other parts of Africa, suggesting the Holocene pattern of vegetation change in Nigeria is a reflection of continental-scale climatic changes.

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Long-term summer warming trend during the Holocene in central Asia indicated by alpine peat α-cellulose δ13C record

Quaternary Science Reviews ◽

10.1016/j.quascirev.2018.11.010 ◽

2019 ◽

Vol 203 ◽

pp. 56-67 ◽

Cited By ~ 22

Author(s):

Zhiguo Rao ◽

Chao Huang ◽

Luhua Xie ◽

Fuxi Shi ◽

Yan Zhao ◽

...

Keyword(s):

Central Asia ◽

Warming Trend ◽

The Holocene ◽

Summer Warming

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Long-Term Solar Forcing of the Holocene Climate

Energy & Environment ◽

10.1177/0958305x9800900615 ◽

1998 ◽

Vol 9 (6) ◽

pp. 741-744 ◽

Cited By ~ 2

Author(s):

W. Karlén

Keyword(s):

Solar Forcing ◽

Holocene Climate ◽

The Holocene

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Three distinct Holocene intervals of stalagmite deposition and nondeposition revealed in NW Madagascar, and their paleoclimate implications

Climate of the Past ◽

10.5194/cp-13-1771-2017 ◽

2017 ◽

Vol 13 (12) ◽

pp. 1771-1790 ◽

Cited By ~ 11

Author(s):

Ny Riavo Gilbertinie Voarintsoa ◽

Loren Bruce Railsback ◽

George Albert Brook ◽

Lixin Wang ◽

Gayatri Kathayat ◽

...

Keyword(s):

Stable Isotopes ◽

High Resolution ◽

Late Holocene ◽

Intertropical Convergence Zone ◽

Convergence Zone ◽

High Resolution Data ◽

The Holocene ◽

Middle Holocene ◽

Resolution Data

Abstract. Petrographic features, mineralogy, and stable isotopes from two stalagmites, ANJB-2 and MAJ-5, respectively from Anjohibe and Anjokipoty caves, allow distinction of three intervals of the Holocene in NW Madagascar. The Malagasy early Holocene (between ca. 9.8 and 7.8 ka) and late Holocene (after ca. 1.6 ka) intervals (MEHI and MLHI, respectively) record evidence of stalagmite deposition. The Malagasy middle Holocene interval (MMHI, between ca. 7.8 and 1.6 ka) is marked by a depositional hiatus of ca. 6500 years. Deposition of these stalagmites indicates that the two caves were sufficiently supplied with water to allow stalagmite formation. This suggests that the MEHI and MLHI intervals may have been comparatively wet in NW Madagascar. In contrast, the long-term depositional hiatus during the MMHI implies it was relatively drier than the MEHI and the MLHI. The alternating wet–dry–wet conditions during the Holocene may have been linked to the long-term migrations of the Intertropical Convergence Zone (ITCZ). When the ITCZ's mean position is farther south, NW Madagascar experiences wetter conditions, such as during the MEHI and MLHI, and when it moves north, NW Madagascar climate becomes drier, such as during the MMHI. A similar wet–dry–wet succession during the Holocene has been reported in neighboring locations, such as southeastern Africa. Beyond these three subdivisions, the records also suggest wet conditions around the cold 8.2 ka event, suggesting a causal relationship. However, additional Southern Hemisphere high-resolution data will be needed to confirm this.

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Agroforestry and Its Impact in Southeast Asia

Oxford Research Encyclopedia of Environmental Science ◽

10.1093/acrefore/9780199389414.013.170 ◽

2020 ◽

Author(s):

Christopher Hunt

Keyword(s):

Land Management ◽

Agroforestry Systems ◽

Management Systems ◽

Early Interventions ◽

Significant Component ◽

The Holocene ◽

Wide Range ◽

Vegetational Succession ◽

Food Procurement

Research during the late 20th and early 21st centuries found that traces of human intervention in vegetation in Southeast Asian and Australasian forests started extremely early, quite probably close to the first colonization of the region by modern people around or before 50,000 years ago. It also identified what may be insubstantial evidence for the translocation of economically important plants during the latest Pleistocene and Early Holocene. These activities may reflect early experiments with plants which evolved into agroforestry. Early in the Holocene, land management/food procurement systems, in which trees were a very significant component, seem to have developed over very extensive areas, often underpinned by dispersal of starchy plants, some of which seem to show domesticated morphologies, although the evidence for this is still relatively insubstantial. These land management/food procurement systems might be regarded as a sort of precursor to agroforestry. Similar systems were reported historically during early Western contact, and some agroforest systems survive to this day, although they are threatened in many places by expansion of other types of land use. The wide range of recorded agroforestry makes categorizing impacts problematical, but widespread disruption of vegetational succession across the region during the Holocene can perhaps be ascribed to agroforestry or similar land-management systems, and in more recent times impacts on biodiversity and geomorphological systems can be distinguished. Impacts of these early interventions in forests seem to have been variable and locally contingent, but what seem to have been agroforestry systems have persisted for millennia, suggesting that some may offer long-term sustainability.

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Centennial to millennial-scale variability of Holocene climate and environmental dynamics in the western Mediterranean (Lake Sidi Ali, Middle Atlas, Morocco)

10.5194/egusphere-egu21-8650 ◽

2021 ◽

Author(s):

Johannes Schmidt ◽

Cathleen Kertscher ◽

Markus Reichert ◽

Helen Ballasus ◽

Birgit Schneider ◽

...

Keyword(s):

North Atlantic ◽

Climate Changes ◽

Western Mediterranean ◽

Future Climate ◽

Holocene Climate ◽

The Holocene ◽

The North ◽

Middle Atlas ◽

Environmental Responses

<p>The Western Mediterranean region including the North African desert margin is considered one of the most sensitive areas to future climate changes. In order to refine long-term scenarios for hydrological and environmental responses to future climate changes in this region, it is important to improve our knowledge about past environmental responses to climatic variability at centennial to millennial timescales. During the last two decades, the recovery and compilation of Holocene records from the subtropical North Atlantic and the Mediterranean Sea have improved our knowledge about millennial-scale variability of the Western Mediterranean palaeoclimate. The variabilities appear to affect regional precipitation patterns and environmental systems in the Western Mediterranean, but the timescales, magnitudes and forcing mechanisms remain poorly known. To compare the changes in Holocene climate variability and geomorphological processes across temporal scales, we analysed a 19.63-m long sediment record from Lake Sidi Ali (33&#176;03&#8217; N, 5&#176;00&#8217; W, 2080 m a.s.l.) in the sub-humid Middle Atlas that spans the last 12,000 years (23 pollen-based radiocarbon dates accompanied with <sup>210</sup>Pb results). We use calibrated XRF core scanning records with an annual to sub-decadal resolution to disentangle the complex interplay between climate changes and environmental dynamics during the Holocene. Data exploration techniques and time series analysis (Redfit, Wavelet) revealed long-term changes in lake behaviour. Three main proxy groups were identified (temperature proxies: 2ky, 1ky and 0.7ky cycles; sediment dynamic proxies: 3.5ky, 1.5ky cycles; hydrological proxies: 1.5ky, 1.2ky, 0.17ky cycles). For example, redox sensitive elements Fe and Mn show 1ky cycles and higher values in the Early Holocene and 1.5ky cycles and lower values in the Mid- to Late Holocene. All groups show specific periodicities throughout the Holocene, demonstrating their particular climatic and geomorphological dependencies. Furthermore, we discuss these periodicities relating to global and hemispheric drivers, such as the North Atlantic Oscillation (NAO), El-Ni&#241;o Southern Oscillation (ENSO), Innertropical Convergence Zone variability (ITCZ) and North Atlantic cold relapses (Bond events).</p>

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Simulation of the 2004 tsunami of Les Saintes in Guadeloupe (Lesser Antilles) using new source constraints

Natural Hazards ◽

10.1007/s11069-020-04073-x ◽

2020 ◽

Vol 103 (2) ◽

pp. 2103-2129

Author(s):

Louise Cordrie ◽

Audrey Gailler ◽

Javier Escartin ◽

Nathalie Feuillet ◽

Philippe Heinrich

Keyword(s):

Lesser Antilles ◽

Les Saintes ◽

2004 Tsunami

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Holocene forest transformations in sandstone landscapes of the Czech Republic: Stand-scale comparison of charcoal and pollen records

The Holocene ◽

10.1177/0959683619854510 ◽

2019 ◽

Vol 29 (9) ◽

pp. 1468-1479 ◽

Cited By ~ 3

Author(s):

Jan Novák ◽

Vojtěch Abraham ◽

Petr Šída ◽

Petr Pokorný

Keyword(s):

Driving Forces ◽

Forest Succession ◽

Environmental Gradients ◽

Silver Fir ◽

Pollen Record ◽

Fire Dynamics ◽

The Czech Republic ◽

The Holocene ◽

Ecosystem Changes

Stand-scale palaeoecology in sandstone landscapes provides insight into contrasting Holocene forest succession trajectories. Sharp geomorphological gradients in this investigated area, which in addition have never been deforested during the Holocene, provide a good model for upscaling the local vegetation histories to the wider territory of Central Europe. In three sandstone areas – Bohemian Paradise, Polemené hory and Broumov – we compare (1) anthracological records from archaeological stratigraphies under rockshelters with (2) pedoanthracological sequences from nearby locations in valleys, rocks and plateaus; and with (3) pollen analyses carried out in nearby peat accumulations. Taphonomical vectors discriminate the source vegetation of each proxy, however thanks to proximity of all sampling sites pollen record and charcoals from rockshelters integrate the signal from pedoanthracology. The results show that past distribution of individual arboreal taxa is clearly related to the position within local environmental gradients. All basic habitats – valleys, rocky edges and plateaus – started with the dominance of pine forest in the early Holocene. Middle Holocene witnessed expansion of spruce inside valleys and oak on plateaus. Pine has maintained its dominance on rocky edges. In the late Holocene, silver fir and beech expanded into valleys, while oak stands remained dominant on plateaus. In the High Medieval and Modern Ages, human impact triggered general spread of fir. Records indicate site-specific local histories connected to various human activities, fire dynamics and erosion. Against the background of these immediate driving forces, the long-term process of ecosystem changes has been influenced by climate of the Holocene.

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