The post-Caledonian thermo-tectonic evolution of Fennoscandia

2021 ◽  
Author(s):  
Peter Japsen ◽  
Paul F. Green ◽  
Johan M. Bonow ◽  
James A. Chalmers ◽  
Ian Duddy ◽  
...  
Keyword(s):  
Middle Jurassic ◽  
Middle Triassic ◽  
Sedimentary Cover ◽  
Late Carboniferous ◽  
Early Miocene ◽  
Plate Tectonic ◽  
Dynamic Topography ◽  
Vertical Movements ◽  
Regional Tectonic ◽  
Atlantic Margin

<p>Here we present apatite fission-track analysis (AFTA) data and thermal history interpretations in 332 samples from outcrops and boreholes at elevations between +2 and -6 km relative to sea level across Fennoscandia. The data define episodes of burial and exhumation which involved deposition and removal of kilometre-scale thicknesses of sediment as well as denudation of the underlying basement rocks that resulted in the formation of peneplains of different age and characteristics.  Many of these episodes correlate with similar episodes over a much wider region, and this argues for regional tectonic control, related to plate-tectonic processes.</p><p>Post-Caledonian development of Fennoscandia involved five dominant episodes of exhumation, beginning in late Carboniferous, Middle Triassic, Middle Jurassic, mid-Cretaceous and early Miocene times.  These episodes affected not only the present-day Atlantic margin but also the continental interior which is considered by many to represent a stable cratonic region because of the low relief and limited remnants of sedimentary cover. Pronounced offsets in the magnitude of the pre-Cenozoic episodes over short distances occur close to the Atlantic margin, and around the Oslo Rift, attesting to the tectonic origin of these episodes.  In contrast, the Middle Triassic and mid-Cretaceous episodes display little variation over vast regions in the interior. Yet even here, our results show that the vertical movements involved deposition and removal of substantial sedimentary covers. </p><p>The late Carboniferous, Middle Triassic and Middle Jurassic episodes can be linked with the break-up of Pangaea.  The mid-Cretaceous episode correlates with a global plate reorganization.  The early Miocene episode appears to be earlier than analogous episodes in Greenland, and it is not yet clear how these episodes fit into the pattern of plate-tectonic forces.  The youngest tectono-thermal episode to affect Fennoscandia began in the early Pliocene and is only revealed by AFTA data from a few deep boreholes. But this episode had a major impact in shaping the present-day topography on both sides of the Atlantic and may have been driven by dynamic support from the Iceland Plume.</p><p>A key aspect of the paleo-thermal episodes identified in this study is that they involve both deposition and removal of kilometre-scale thicknesses of sediment (i.e. subsidence and uplift), rather than progressive emergence and monotonic cooling of the continents as assumed in many studies.  Dynamic topography and far-field transmission of stress thus appear to be likely candidates for driving the ups and downs of both marginal and interior regions. </p>

scholarly journals Improving global paleogeography since the late Paleozoic using paleobiology

2017 ◽  
Author(s):  
Wenchao Cao ◽  
Sabin Zahirovic ◽  
Nicolas Flament ◽  
Simon Williams ◽  
Jan Golonka ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Mantle Convection ◽  
Growth Models ◽  
Plate Motion ◽  
Late Paleozoic ◽  
Plate Tectonic ◽  
Dynamic Topography ◽  
Tectonic Reconstructions ◽  
Marine Boundaries ◽  
Continental Growth

Abstract. Paleogeographic reconstructions are important to understand Earth's tectonic evolution, past eustatic and regional sea level change, hydrocarbon genesis, and to constrain and interpret the dynamic topography predicted by time-dependent global mantle convection models. Several global paleogeographic maps have been compiled and published but they are generally presented as static maps with varying temporal resolution and fixed spatial resolution. Existing global paleogeographic maps are also tied to a particular plate motion model, making it difficult to link them to alternative digital plate tectonic reconstructions. To address this limitation, we developed a workflow to reverse-engineer global paleogeographic maps to their present-day coordinates and enable them to be linked to any tectonic reconstruction. Published paleogeographic compilations are also tied to fixed input datasets. We used fossil data from the Paleobiology Database to identify inconsistencies between fossils paleo-environments and published paleogeographic maps, and to improve the location of inferred terrestrial-marine boundaries by resolving these inconsistencies. As a result, the overall consistency ratio between the paleogeography and fossil collections was improved from 76.9 % to 96.1 %. We estimated the surface areas of global paleogeographic features (shallow marine environments, landmasses, mountains and ice sheets), and reconstructed the global continental flooding history since the late Paleozoic based on the amended paleogeographies. Finally, we discuss the relationships between emerged land area and total continental crust area through time, continental growth models, and strontium isotope (87Sr/86Sr) signatures in ocean water. Our study highlights the flexibility of digital paleogeographic models linked to state-of-the-art plate tectonic reconstructions in order to better understand the interplay of continental growth and eustasy, with wider implications for understanding Earth's paleotopography, ocean circulation, and the role of mantle convection in shaping long-wavelength topography.

Where are the proto-South China Sea slabs? SE Asia plate tectonic and mantle flow insights from TERRA global mantle convection models

2020 ◽  
Author(s):  
Yi-An Lin ◽  
Lorenzo Colli ◽  
Jonny Wu
Keyword(s):  
South China Sea ◽  
South China ◽  
Late Eocene ◽  
Early Miocene ◽  
Philippine Sea Plate ◽  
Plate Tectonic ◽  
China Sea ◽  
Se Asia ◽  
Plate Models ◽  
Geodynamic Models

<p>In this study we explored the contrasted plate tectonic reconstructions proposed for the proto-South China Sea and SE Asia. We implemented four different end-member plate models into global geodynamic models to test their predicted mantle structure against tomography. All models reproduced the Sunda slabs beneath Peninsular Malaysia, Sumatra and Java and the proto-South China Sea (PSCS) slabs beneath present Palawan, northern Borneo, and offshore Palawan; some models also predicted slabs under the southern South China Sea. PSCS slabs generated from double-sided PSCS subduction and earlier Borneo rotation generated a slightly better fit to tomography but pure southward PSCS subduction was also viable. A smaller Philippine Sea plate (PSP) with a short ~1000 km restored northern slab (i.e. Ryukyu slab) was clearly superior to a very long >3000 km slab. Mantle flows generated from our geodynamic models suggest strong upwellings under Indochina during the late Eocene to Oligocene. Our models generated strong downwellings under the South China Sea in the late Cenozoic that did not support a deep-origin ‘Hainan plume’. </p><p>The following plate models variants were assimilated in the geodynamic models: (1) southward vs. double-sided PSCS subduction; (2) early Borneo counterclockwise rotations during the Oligocene to Early Miocene vs. later rotations (mid- to Late Eocene and Early Miocene); (3) a smaller Philippine Sea plate restored with a shorter ~1000 km northern slab vs. a longer >3000 km slab. This study assimilates four different plate models into the numerical model TERRA (Bunge et al., 1998). We digitally re-built in GPlates (Boyden et al., 2011) the implemented the plate models as a set of continuously closing plates in order to generate a global self-consistent velocity field to be assimilated into the convection models. The temperature fields were converted to seismic velocities assuming a Pyrolite composition and equilibrium mineralogy. We quantify the correlation between our geodynamic models and seismic tomography within SE Asia. For the tomography models S40RTS and LLNL-G3Dv-JPS we explicitly accounted for their finite resolution (Ritsema et al., 2011; Simmons et al. 2019).</p>

scholarly journals Age and microfacies of oceanic Upper Triassic radiolarite components from the Middle Jurassic ophiolitic mélange in the Zlatibor Mountains (Inner Dinarides, Serbia) and their provenance

2017 ◽  
Vol 68 (4) ◽  
pp. 350-365 ◽  
Author(s):  
Hans-Jürgen Gawlick ◽  
Nevenka Djerić ◽  
Sigrid Missoni ◽  
Nikita Yu. Bragin ◽  
Richard Lein ◽  
...  
Keyword(s):  
Continental Slope ◽  
Oceanic Crust ◽  
Middle Jurassic ◽  
Sedimentary Cover ◽  
Upper Triassic ◽  
Late Triassic ◽  
Ophiolitic Mélange ◽  
Reef Limestone ◽  
Sedimentary Succession ◽  
Unit Yield

AbstractOceanic radiolarite components from the Middle Jurassic ophiolitic mélange between Trnava and Rožanstvo in the Zlatibor Mountains (Dinaridic Ophiolite Belt) west of the Drina–Ivanjica unit yield Late Triassic radiolarian ages. The microfacies characteristics of the radiolarites show pure ribbon radiolarites without crinoids or thin-shelled bivalves. Beside their age and the preservation of the radiolarians this points to a deposition of the radiolarites on top of the oceanic crust of the Neo-Tethys, which started to open in the Late Anisian. South of the study area the ophiolitic mélange (Gostilje–Ljubiš–Visoka–Radoševo mélange) contains a mixture of blocks of 1) oceanic crust, 2) Middle and Upper Triassic ribbon radiolarites, and 3) open marine limestones from the continental slope. On the basis of this composition we can conclude that the Upper Triassic radiolarite clasts derive either from 1) the younger parts of the sedimentary succession above the oceanic crust near the continental slope or, more convincingly 2) the sedimentary cover of ophiolites in a higher nappe position, because Upper Triassic ribbon radiolarites are only expected in more distal oceanic areas. The ophiolitic mélange in the study area overlies different carbonate blocks of an underlying carbonate-clastic mélange (Sirogojno mélange). We date and describe three localities with different Upper Triassic radiolarite clasts in a mélange, which occurs A) on top of Upper Triassic fore-reef to reefal limestones (Dachstein reef), B) between an Upper Triassic reefal limestone block and a Lower Carnian reef limestone (Wetterstein reef), and C) in fissures of an Upper Triassic lagoonal to back-reef limestone (Dachstein lagoon). The sedimentary features point to a sedimentary and not to a tectonic emplacement of the ophiolitic mélange (= sedimentary mélange) filling the rough topography of the topmost carbonate-clastic mélange below. The block spectrum of the underlying and slightly older carbonate-clastic mélange points to a deposition of the sedimentary ophiolitic mélange east of or on top of the Drina–Ivanjica unit.

Geology of the Cadwallader Group and the Intermontane–Insular superterrane boundary, southwestern British Columbia

1987 ◽  
Vol 24 (11) ◽  
pp. 2279-2291 ◽  
Author(s):  
Margaret E. Rusmore
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Tectonic Evolution ◽  
Middle Triassic ◽  
Upper Triassic ◽  
Tectonic Block ◽  
Volcanic Arc ◽  
Arc Volcanism ◽  
Clastic Rocks ◽  
Tectonic Settings

Several lower Mesozoic, fault-bounded units separate the Intermontane and Insular superterranes in southwestern British Columbia. Detailed study of one of these Mesozoic units, the Cadwallader Group, helps clarify the boundary between the superterranes and establish the tectonic evolution of southwestern British Columbia. The Cadwallader Group is the oldest unit in an Upper Triassic through Middle Jurassic volcanic and sedimentary tectono-stratigraphic terrane. Two formations, the Pioneer and the Hurley, compose the Cadwallader Group; the previously recognized Noel Formation is no longer considered valid. The Pioneer Formation contains pillow basalt, flows, and basalt breccia. Siltstone, sandstone, conglomerate, and minor amounts of limestone megabreccia and basalt belonging to the Hurley Formation conformably overlie the Pioneer. The Hurley spans latest Carnian or earliest Norian to middle Norian time. Two episodes of deformation affected the Cadwallader, and a thrust fault separates the group from slightly younger clastic rocks of the Tyaughton Group. Similarities in clastic rocks indicate the Tyaughton was deposited on the Cadwallader; together the units form the Cadwallader terrane. Basalts and clastic rocks in the terrane record deposition in or near a Carnian to earliest Norian volcanic arc. Volcanism waned later in the Norian, but presence of the arc is preserved in the clastic rocks.Oceanic rocks of the Middle Triassic to Middle Jurassic Bridge River terrane became juxtaposed with the Cadwallader terrane in Middle Jurassic time, after which the terranes functioned as a single tectonic block. Contrasting volcanic histories suggest that the Cadwallader terrane was not accreted to the Intermontane superterrane until Middle Jurassic or Early Cretaceous time, although the similar tectonic settings of Stikinia and the Cadwallader terrane allow a common earlier history. The Cadwallader terrane is not part of either the Alexander terrane or Wrangellia, and so the inboard margin of the Insular superterrane must lie west of the Cadwallader terrane.

scholarly journals Assessment of hydrocarbon potential of Jurassic and Cretaceous source rocks in the Tarnogród-Stryi area (SE Poland and W Ukraine)

2012 ◽  
Vol 63 (4) ◽  
pp. 319-333 ◽  
Author(s):  
Paweł Kosakowski ◽  
Dariusz Więcław ◽  
Adam Kowalski ◽  
Yuriy Koltun
Keyword(s):  
Organic Matter ◽  
Middle Jurassic ◽  
Sedimentary Cover ◽  
Source Rocks ◽  
Hydrocarbon Potential ◽  
Hydrocarbon Generation ◽  
Hydrocarbon Source Rock ◽  
Core Samples ◽  
Se Poland ◽  
Geochemical Parameters

Assessment of hydrocarbon potential of Jurassic and Cretaceous source rocks in the Tarnogród-Stryi area (SE Poland and W Ukraine) The Jurassic/Cretaceous stratigraphic complex forming a part of the sedimentary cover of both the eastern Małopolska Block and the adjacent Łysogóry-Radom Block in the Polish part as well as the Rava Rus'ka and the Kokhanivka Zones in the Ukrainian part of the basement of the Carpathian Foredeep were studied with geochemical methods in order to evaluate the possibility of hydrocarbon generation. In the Polish part of the study area, the Mesozoic strata were characterized on the basis of the analytical results of 121 core samples derived from 11 wells. The samples originated mostly from the Middle Jurassic and partly from the Lower/Upper Cretaceous strata. In the Ukrainian part of the study area the Mesozoic sequence was characterized by 348 core samples collected from 26 wells. The obtained geochemical results indicate that in both the south-eastern part of Poland and the western part of Ukraine the studied Jurassic/Cretaceous sedimentary complex reveals generally low hydrocarbon source-rock potential. The most favourable geochemical parameters: TOC up to 26 wt. % and genetic potential up to 39 mg/g of rock, were found in the Middle Jurassic strata. However, these high values are contradicted by the low hydrocarbon index (HI), usually below 100 mg HC/g TOC. Organic matter from the Middle Jurassic strata is of mixed type, dominated by gas-prone, Type III kerogen. In the Polish part of the study area, organic matter dispersed in these strata is generally immature (Tmax below 435 °C) whereas in the Ukrainian part maturity is sufficient for hydrocarbon generation.

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