Geologic evolution and geodynamic controls of the Tertiary intramontane piggyback Meso-Hellenic basin, Greece

2004 ◽  
Vol 175 (4) ◽  
pp. 361-381 ◽  
Author(s):  
Jacky Ferrière ◽  
Jean-Yves Reynaud ◽  
Andreas Pavlopoulos ◽  
Michel Bonneau ◽  
Georges Migiros ◽  
...  
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Late Eocene ◽  
Tectonic Activity ◽  
Tectonic Structures ◽  
Fine Grained ◽  
Piggyback Basin ◽  
Global Sea Level ◽  
Continental Basin ◽  
Tectonic Boundary

Abstract The Meso-Hellenic Basin (MHB) is a large, narrow and elongated basin containing up to c. 5 km of Cenozoic sediments, which partially covers the tectonic boundary between the external, western zones (Pindos) and the internal, eastern zones (Pelagonian) of the Hellenide fold-and-thrust belt. New results, based on micropaleontologic, sedimentologic and tectonic field data from the southern half of the MHB, suggest that the MHB originated as a forearc basin during the first stages of a subduction (Pindos basin), and evolved into a true piggyback basin as a result of the collision of thicker crustal units (Gavrovo-Tripolitsa). The late Eocene forearc stage is marked by sharply transgressive, deep sea turbiditic deposition on the subsiding active margin. At this stage, large scale structures of the Pelagonian basement (i.e. the newly defined “Pelagonian Indentor”) control deposition and location of two main subsiding sub-basins located on both sides of the MHB. The Eocene-Oligocene boundary corresponds to a brief tectonic inversion of the basin, at the onset of collision (main compressive event). The true piggyback stage (Oligo-Miocene) is recorded by slope deposition and dominated by gravity processes (from slumped, fine grained turbidites to conglomeratic fan- or Gilbert-deltas). The new elongated geometry of the MHB is controlled by the underthrusted, NNW-SSE trending, thick external zones. During this stage, the locus of subsidence migrates in the same direction (eastward) as underthrusting. This subsidence, favoured by thick dense ophiolitic basement, is attributed to basal tectonic erosion of the upper Pelagonian unit while the tectonic structures of this upper unit control the stepped migration of subsidence. Growing duplexes in the Gavrovo underthrusted unit, which formed local uplifts, were mainly situated on the eastern side of the subsiding areas and associated with normal faulting (late Oligocene–early Miocene). They constituted new loads that could also have been responsible for minor but widespread lithospheric subsidence. The development of the local and regional uplifts explains the basin evolution toward shallow, dominantly conglomeratic deposits and its final emergence at the end of the middle Miocene. This trend toward emersion is emphasized by the late Miocene global sea-level fall. The MHB was subsequently overprinted by neotectonic deformation associated with the development of a continental basin (Ptolemais) and uplift attributed to the evolution of the Olympos structure that developed further east as the underthrusting moved in this direction. These results demonstrate that the Meso-Hellenic Basin evolves as a large scale piggyback Basin and that its sedimentary infill is largely controled by tectonic activity rather than only eustatic sea-level variations.

Periodically forced self-organization in the long-term evolution of planktic foraminifera

2001 ◽  
Vol 38 (2) ◽  
pp. 293-308 ◽  
Author(s):  
Andreas Prokoph ◽  
Anthony D Fowler ◽  
R Timothy Patterson
Keyword(s):  
Sea Level ◽  
Logistic Map ◽  
Late Eocene ◽  
Self Organization ◽  
Extinction Data ◽  
Sea Level Fluctuations ◽  
Global Sea Level ◽  
Extinction Events ◽  
The Impact

Wavelet transform and other signal analysis techniques suggest that the planktic foraminiferal (PF) long-term evolutionary record of the last 127 Ma can be attributed to complex periodic and nonlinear patterns. Correlation of the PF extinction pattern with other geological series favors an origin of the ~30 Ma periodicity and self-organization by quasi-periodic mantle-plume cycles that in turn drive episodic volcanism, CO2-degassing, oceanic anoxic conditions, and sea-level fluctuations. Stationary ~30 Ma periodicity and a weak secular trend of ~100 Ma period are evident in the PF record, even without consideration of the mass extinction at the K–T boundary. The 27–32 Ma periodicity in the impact crater record and lows in the global sea-level curve, respectively, are ~6.5 Ma and ~2.3 Ma out of phase with PF-extinction data, although major PF-extinction events correspond to the bolide impacts at the K–T boundary and in late Eocene. Another six extinction events correspond to abrupt global sea-level falls between the late Albian and early Oligocene. Self-organization in the PF record is characterized by increased radiation rates after major extinction events and a steady number of baseline species. Our computer model of long-term PF evolution replicates this SO pattern. The model consists of output from the logistic map, which is forced at 30 Ma and 100 Ma frequencies. The model has significant correlations with the relative PF-extinction data. In particular, it replicates singularities, such as the K–T event, nonstationary 2.5–10 Ma periodicities, and phase shifts in the ~30 Ma periodicity of the PF record.

Towards disentangling climatic and tectonic changes of southernmost Africa using strontium isotope stratigraphy and clumped isotope thermometry

2021 ◽  
Author(s):  
B. Linol ◽  
I. Montañez ◽  
A. Lombardo ◽  
D. Kuta ◽  
D. Upadhyay ◽  
...  
Keyword(s):  
South Africa ◽  
Sea Level Rise ◽  
Sea Level ◽  
Secondary Ion Mass Spectrometry ◽  
Isotope Composition ◽  
Tectonic Activity ◽  
Elemental Ratios ◽  
Strontium Isotope Stratigraphy ◽  
Clumped Isotope ◽  
Global Sea Level

Abstract Upper Cretaceous-Cenozoic marine sequences preserved between 30 and 350 masl across southern South Africa record a complex history of climatic and tectonic changes. In this study, we measure the strontium (Sr) isotope composition of fossil shark teeth, echinoderms, corals and oyster shells to chronostratigraphically constrain the ages of these sequences. The method requires careful petrographic screening and micro-drilling of the samples to avoid possible alteration by diagenesis. To assess palaeoenvironmental effects in the shells we measured the Mg/Ca elemental ratios and O isotope values using electron microprobe analysis (EMPA) and secondary ion mass spectrometry (SIMS). In addition, we employed carbonate clumped isotope thermometry to test palaeotemperatures reconstruction. The analysis of recent to modern stromatolites by clumped isotopes yields an average temperature of 20.2°C, in agreement with present day observations. The fossil oyster shells suggest a warmer (23.0°C) seawater palaeotemperature, possibly due to major deglaciation and sea-level rise during the Neogene. We also find that transgressions occurred above 200 to 350 m elevation during: 1) the Campanian-Maastrichian (~75 Ma); 2) the mid-Oligocene (32 to 26 Ma); and 3) the Messinian-Zanclean (6 to 5 Ma). These three episodes are linked to well-known variations in global sea level and regional tectonic processes that could have affected the continental margin differently. The most recent transgression coincides with a maximum global sea-level rise of ~50 m at ca. 5.3 Ma, and a worldwide plate kinematic change around 6 Ma, which in Eurasia led to the closure of the Mediterranean Sea. In the Eastern Cape of South Africa, the new dates of analyzed oyster shells constrain a minimum uplift rate of ca. 150 m/Myr during this tectonic activity. The results have important implications for robust calibration of relative sea level in southern Africa.

scholarly journals Delta Deposits on Mars: A Global Perspective

2021 ◽  
Author(s):  
Barbara De Toffoli ◽  
Ana-Catalina Plesa ◽  
Ernst Hauber ◽  
Doris Breuer
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Global Scale ◽  
Channel Length ◽  
Global Perspective ◽  
Martian Surface ◽  
Environmental Implications ◽  
Complete Mapping ◽  
Level Elevation ◽  
Global Sea Level

<p>The presence of delta deposits on Mars has been thoroughly demonstrated for decades and large scale mapping [1,2] highlighted the presence of several delta fans mainly located on the dichotomy boundary. While a previous delta inventory was compiled by Morgan et al. [3], we aim to update and finalize a complete mapping of delta deposits in order to allow the examination of the evolution and distribution of standing bodies of water on Mars. The objective of our project focuses on the production of a global catalogue of water-related features at the Martian surface, which are commonly studied separately or at smaller scales.</p><p>Globally, we located around 150 deltas among which many were not previously included in published literature [e.g. 1,2,4]. We then examined the deltas based on two main traits. Firstly, we measured the length of the feeding channels since it may be (i) a proxy for the duration of the aqueous activity in the channel-delta system, and (ii) proportional to the age of the delta [2]. The latter relationship links older deltas near Chryse Planitia (>3 Ga) to longer valleys, while younger deltas are usually fed by shorter valleys [2]. Secondly, we measured the elevation of the delta population and compared the obtained dataset with the hypothesized sea level elevation of -2540 ± 177 m firstly suggested by Di Achille and Hynek [1] for a northern ocean through the analysis of deltas.</p><p>We observed that, if the relationship between feeding channel length and delta age found for a sub-group of the population [2] is applicable as a rule of thumb to all deltas, many of the deposits have the potential to be Hesperian or Amazonian in age. They would thus be younger than the ocean that might have occupied the northern lowlands during the Noachian-Hesperian boundary period [1] and thus be unrelated to a global sea level range. In fact, less than half of the delta population is related to medium/long feeding channels (>30 km). Abundant pristine morphologies, both related to channels and deltas, also supports the hypothesis that part of the population is younger than Noachian. Additionally, the large variety of elevations where the deltaic deposits can be found and the very small amount of deltas included in the sea level elevation range proposed by Di Achille and Hynek [1] raise questions about the generation and environmental implications of these features, especially when seen at global scale.</p><p> </p><p>[1] Di Achille, G. & Hynek, B. M., Nat. Geosci. 3, 459–463 (2010).</p><p>[2] Hauber, E. et al., J. Geophys. Res. E Planets 118, 1529–1544 (2013).</p><p>[3] Morgan, A. M., et al., Lunar Planet. Sci. Conf. (2018).</p><p>[4] Ori, G.G. et al., J. Geophys. Res. E Planets 105, 17629–17641 (2000).</p>

scholarly journals MIOCENE SCLERACTINIAN CORALS OF GAVDOS ISLAND, SOUTHERN GREECE: IMPLICATIONS FOR TECTONIC CONTROL AND SEA-LEVEL CHANGES

2017 ◽  
Vol 43 (2) ◽  
pp. 620
Author(s):  
H. Drinia ◽  
F. Pomoni-Papaioannou ◽  
Tsaparas N. ◽  
A. Antonarakou
Keyword(s):  
Sea Level ◽  
Eastern Mediterranean ◽  
High Energy ◽  
Tectonic Activity ◽  
Sea Level Changes ◽  
Reef Facies ◽  
Reef Development ◽  
Patch Reefs ◽  
Tectonically Active ◽  
Global Sea Level

Low-diversity scleractinian patch reefs that have been developed, during Early to Middle Tortonian, in Gavdos island are studied, aiming in a better understanding of the time and space relationships of the reef development and the associated basin fill evolution. Gavdos island consists part of a tectonically active setting constituting the southernmost extension of the Hellenic arc (Eastern Mediterranean). A representative Tortonian section (Bo section), located in the northwest part of the island, which hosts a mass occurrence of hermatypic corals, is studied. Scleractinian samples were collected from the upper 12 m of the section, which is characterized by interchanges of marly limestone and compact marls. The reefs are represented by the coral species Heliastraea oligophylla, Porites maicientensis, Thegioastraea roasendai and Porites collegniana. The microfacies analysis showed that the mediumto-thin-bedded carbonates of the limestone-marl alternations comprise patch reefs (boundstones-framestones, SMF 16, sensu Wilson, 1975, FZ 7-8, sensu Flügel 1982) consisted of screractinian corals. Corals are associated with corallinacean algae. Patch reefs are associated by bioclastic packstones-floatstones, characterized by benthic foraminifera, calcareous algae, spines of echinoids, gastropods and molluscs. Reefs are laterally associated by a bioclastic limestone rich in planktonic forams, associated by detrital material (fragments of quartz, feldspars, quartzites and cherts). The studied reef facies have been dolomitized and cemented in the meteoric realm. In places pseudomorphs after evaporites have been observed, tending to occlude cavities resulted after dissolution. The depositional environment corresponds to a moderate to high-energy inner platform setting, experiencing open-ocean influences. The pattern of coralgal reef development during Miocene, in the tectonically controlled Gavdos island, represents a complex interaction of tectonic activity and global sea-level changes.

scholarly journals Geological And Morphological Evolution of The Socotra Archipelago (Yemen) from the Biogeographical View

2013 ◽  
Vol 6 (3) ◽  
pp. 84-108 ◽  
Author(s):  
Martin Culek
Keyword(s):  
Sea Level ◽  
Land Surface ◽  
Large Scale ◽  
Morphological Evolution ◽  
Late Eocene ◽  
Gulf Of Aden ◽  
Quaternary Period ◽  
New Information ◽  
Terrestrial Biota ◽  
Socotra Archipelago

Abstract Some misunderstandings persist in the biological literature, concerning the geological evolution of the Socotra Archipelago. The aim of this paper is to interpret new information about the Gulf of Aden geology, from the view of possible methods of terrestrial biota species migration to the Socotra Islands. An overview of the Socotra Platform with the Socotra Archipelago topography is given. Present-day geological publications are mostly oriented towards tectonic structure of the Gulf and its tectonic evolution, and thus information concerning the elevation of the land surface and the sea level was necessary to deduce. The first biogeographically relevant emergence of a land mass in the area of present-day Socotra Archipelago commenced during the late Eocene Epoch (38-34 Ma BP). Some islands persisted after later transgressions of the sea, before the time of the opening of the Gulf of Aden rift (ca 20-17 Ma), accompanied by substantial uplift and large-scale uplift of the land. This was the last time when terrestrial biota could, relatively easily, reach the area of the Socotra Archipelago on land from the African mainland, and also with medium probability from present-day Arabia. The total evaporation of the Red Sea from 11-5 Ma BP enabled the migration of terrestrial species from and to Arabia via Somalia. Nevertheless, channels in Guardafui and Brothers basins made important, but perhaps nonfatal, barriers. The last and most important uplift of Haggier Mts. on Socotra occurred at the end of the Miocene Epoch (9-6 Ma BP). That was probably the time of the last Tertiary emergence of the Socotra Platform, potentially enabling some species to migrate across narrowed abovementioned channels. Great changes in sea level occurred during the Quaternary Period, periodically exposing the surface of the Socotra platform. Two channels persisted, preventing the invasion of modern species onto the Socotra Archipelago. Channels within the Brothers basin between Abd al-Kuri Isl. and other islands of the Archipelago formed some barriers to dispersal, and probably led to important biota differences in the scope of the Archipelago. Finally, a scenario of the “facilitation” provided by tsunami and sea currents for the immigration of biota onto the Archipelago is presented.

Deriving a Physically-Based Calving Rate Law for Marine Ice-Cliff Instability

2020 ◽  
Author(s):  
Anna Crawford ◽  
Joe Todd ◽  
Doug Benn ◽  
Jan Åström ◽  
Thomas Zwinger
Keyword(s):  
Viscous Flow ◽  
Sea Level Rise ◽  
Sea Level ◽  
Large Scale ◽  
Ice Sheet ◽  
Rate Law ◽  
Grounding Line ◽  
Physically Based ◽  
Calving Rate ◽  
Global Sea Level

<p><span>Rapid grounding line retreat at marine-terminating glaciers could expose ice cliffs with heights greater than those on observational record. However, the finite strength of ice places a limit on the height of subareal cliffs. It is proposed that marine ice-cliff instability (MICI) will begin once a stable height threshold is exceeded. If a glacier is situated over a retrograde slope, as is the case for Thwaites Glacier and much of the West Antarctic Ice Sheet, MICI can be expected to accelerate </span><span>as retreat progresses</span><span> and increasingly tall and unstable ice cliffs are </span><span>formed. This is consequential for global sea level rise, yet large uncertainties remain in the prediction of MICI retreat rates. </span></p><p><span>We investigate MICI by pairing the full Stokes continuum model Elmer/Ice and the Helsinki Discrete Element Model (HiDEM)</span><span>. Viscous flow, simulated in Elmer/Ice, is found to be a necessary pre-condition for MICI collapse. Forward advance and bulging lead to ice-front instability and pervasive crevassing in HiDEM. This culminates in full-thickness calving events. We do not observe calving at ice faces prior to viscous deformation. </span><span>HiDEM simulations that implement viscous flow (HiDEM-ve) also show forward advance and waterline bulging, similar to the Elmer/Ice simulations. However, the importance of granular shear is highlighted by pronounced shear bands and patterns of surface lowering in HiDEM-ve output. These results emphasize the importance and complexity of viscous and brittle process interaction during MICI.</span></p><p><span>A simulation matrix of grounded termini shows that calving frequency and magnitude increase with the thickness of the calving front. The time required for viscous flow to recreate unstable conditions is influenced by thickness as well as ice temperature and basal friction. Simulations of buoyant termini are seen to calve through basal-crevassing and block-rotation, as opposed to incising surface-crevasses. Lastly, we observe that b</span><span>uttressing </span><span>mélange can</span><span> suppress retreat rate</span><span> if a sufficient resistive force is delivered to the calving front. A </span><span>physically-based law for MICI retreat rate is derived from our simulation matrix; this calving rate law can be incorporated into large-scale ice sheet models to constrain projections of Antarctic retreat and associated global sea level rise. Our results will also be used to investigate the future retreat of Thwaites Glacier, which is vulnerable to MICI due to a retreating grounding line, fragile floating ice shelf, and precarious positioning above an overdeepening basin</span><span>. </span></p>

scholarly journals Tracking Long-Term Changes in Global Sea Level Extremes

Eos ◽  
2016 ◽  
Author(s):  
Sarah Stanley
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Large Scale ◽  
Long Term Changes ◽  
Global Sea Level

Large-scale climate change may drive trends in extreme sea level events.

New insights on Illinoian deglaciation from deposits of Glacial Lake Quincy, central Indiana

2010 ◽  
Vol 73 (2) ◽  
pp. 374-384 ◽  
Author(s):  
J.R. Wood ◽  
S.L. Forman ◽  
J. Pierson ◽  
J. Gomez
Keyword(s):  
Oxygen Isotope ◽  
Sea Level ◽  
Lacustrine Sediments ◽  
Glacial Lake ◽  
Depositional Facies ◽  
Oxygen Isotope Stage ◽  
Fine Grained ◽  
Blue Excitation ◽  
Global Sea Level ◽  
Maximum Limit

The deposits of Glacial Lake Quincy overlie a diamicton associated with the classically defined Illinoian limit in central Indiana. This lake covered at least 180 km2 with a depth of > 20 m and developed when the Illinoian ice sheet retreated 15 km from the maximum limit, causing lake impoundment against Devore Ridge. Overflow from Glacial Lake Quincy eroded across the ridge forming a number of steeped-walled outlets. A section along Mill Creek exposes a sedimentologic sequence associated with Glacial Lake Quincy from a subglacial diamicton to ice-proximal to ice-distal glacial lacustrine sediments. We report new optical ages by multiple aliquot regenerative dose procedure for the fine-grained rhythmically bedded sediments presumed to represent the lowest energy depositional facies, dominated by suspension settling, which maximized sunlight exposure. In turn, optical ages were determined on the fine-grained (4-11 μm) polymineral and quartz fractions under infrared and blue excitation, which yielded statistically similar ages. Optical ages span from ca. 170 to 108 ka, with the average of 16 optical ages indicating deglaciation at ca. 135 ka, generally coincident with Marine Oxygen Isotope Stage 6-to-5 transition and rise in global sea level.

scholarly journals Long-term shoreline shifts on continental blocks during the Bajocian: an updated interpretation based on synthetic stratigraphical and palaeogeographical developments on regional scales

Geologos ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Dmitry A. Ruban ◽  
Emad S. Sallam
Keyword(s):  
Sea Level ◽  
Western Siberia ◽  
Control Mechanism ◽  
Russian Platform ◽  
Tectonic Activity ◽  
Sea Level Changes ◽  
Regional Tectonic ◽  
Global Sea Level ◽  
Apparent Stability

Abstract Available reconstructions of Jurassic global sea level changes differ and are in need of an update. New stratigraphical charts and palaeogeographical developments for a number of large continental blocks or their portions of these (e.g., Germany, India, northeast Africa, northwest Australia, the Russian Platform and western Siberia) reveal regional long-term shoreline shifts (i.e., transgressions and regressions) during the Bajocian Stage (168.3–170.3 Ma). A comparison of these allows to document only a single coherent feature, namely the earliest Bajocian transgression, in the majority of the continental blocks considered. Undoubtedly, this event was triggered by a eustatic rise. However, long-term shoreline shifts were either weak to absent or differed between the blocks during almost the entire Bajocian, thus providing evidence of the apparent stability of global sea level and the importance of regional tectonic activity as a control mechanism on particular transgressions and regressions. Interestingly, it appears that the earliest Bajocian eustatic rise was a constituent of a long-term eustatic pattern; the nature of this event has yet to be fully understood. Generally, the findings presented here are in better agreement with Anthony Hallam’s view of Jurassic eustasy and question some other global sea level reconstructions.

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