A Cretaceous Neo-Tethyan carbonate margin in Argolis, southern Greece

1990 ◽  
Vol 127 (4) ◽  
pp. 299-308 ◽  
Author(s):  
Peter D. Clift ◽  
Alastair H. F. Robertson
Keyword(s):  
Late Cretaceous ◽  
Foreland Basin ◽  
Ocean Basin ◽  
Passive Margin ◽  
Accretionary Complex ◽  
Early Tertiary ◽  
Thrust Sheets ◽  
Pelagonian Zone ◽  
Structural Levels ◽  
Southern Greece

AbstractThe Argolis Peninsula, southern Greece, is believed to form part of a Pelagonian microcontinent located between two oceanic basins, the Pindos to the west and theVardar to the east, in Triassic to Tertiary time. In eastern Argolis, two important units are exposed: (i) the Ermioni Limestones cropping out in the southwest; (ii) the Poros Formation, observed on an offshore island in the northeast, and on the adjacent mainland. Both these units comprise late Cretaceous (Aptian-Maastrichtian) pelagic limestones, calciturbidites, lenticular matrix- and clast-supported limestone conglomerates and slump sheets. However, the Poros Formation is distinguished from the Ermioni Limestones by the presence of bituminous micritic limestones and an increasing proportion of shale up sequence. These successions are deep-water slope carbonates that once formed the southeast-facing passive margin of the Pelagonian platform (Akros Limestone). Beyond this lay a late Cretaceous ocean basin in the Vardar Zone. This ocean was consumed in an easterly-dipping subduction zone in latest Cretaceous (?) to early Tertiary time, giving rise to an accretionary complex (Ermioni Complex). During early Tertiary (Palaeocene-Eocene) time the passive continental margin (Pelagonian Zone) collided with the trench and accretionary complex to the east. As the suture tightened, former lower-slope carbonates (Ermioni Limestones) were accreted to the base of the over-riding thrust sheets and emplaced onto the platform. Farther west, bituminous upper slope carbonates (Poros Formation) flexurally subsided and passed transitionally upwards into calcareous flysch and olistostromes in a foreland basin. These sediments were then overridden by the emplacing thrust stack and themselves underplated. Late-stage high-angle faulting then disrupted the tectonostratigraphy, in places juxtaposing relatively high and low structural levels of the complex.

First sedimentary record of the pre-obduction convergence in New Caledonia: formation of an Early Eocene accretionary complex in the north of Grande Terre and emplacement of the ‘Montagnes Blanches’ nappe

2011 ◽  
Vol 182 (6) ◽  
pp. 479-491 ◽  
Author(s):  
Pierre Maurizot
Keyword(s):  
Late Cretaceous ◽  
New Caledonia ◽  
Sedimentary Cover ◽  
Planktonic Foraminifera ◽  
Foreland Basin ◽  
Late Eocene ◽  
Passive Margin ◽  
Early Eocene ◽  
Accretionary Complex ◽  
The North

Abstract New Caledonia lies at the northern tip of the Norfolk ridge, a continental fragment separated from the east Gondwana margin during the Late Cretaceous. Stratigraphic data for constraining the convergence that led to ophiolitic nappes being obducted over Grande Terre during the Eocene are both few and inaccurate. To try and fill this gap and determine the onset of the convergence, we investigated the lithology, sedimentology, biostratigraphy and geodynamic context of the Late Cretaceous – Palaeogene sedimentary cover-rock succession of northern New Caledonia. We were able to establish new stratigraphic correlations between the sedimentary units, which display large southwest-verging overfolds detached along a basal argillite series, and reinterpret their interrelationships. The sediments from the Cretaceous-Paleocene interval were deposited in a post-rift pelagic environment and are mainly biogenic with minimal terrigenous input. From the base up, they comprise black organic-rich sulphide-bearing argillite, black chert (silicified equivalent of the argillite), micritic with chert, and micrite rich in planktonic foraminifera. These passive-margin deposits are found regionally on the Norfolk Ridge down to New Zealand, and on the Lord Howe Rise, and were controlled primarily by regional or global environmental factors. The overlying Eocene deposits mark a change to an active-margin regime with distal calciturbidite and proximal breccia representing the earliest Paleogene flysch-type deposits in New Caledonia. The change from an extensional to a compressive regime marks the beginning of the pre-obduction convergence and can be assigned fairly accurately in the Koumac–Gomen area to the end of the Early Eocene (Late Ypresian, Biozone E7) at c 50 Ma. From this period on, the post-Late Cretaceous cover in northern New Caledonia was caught up and recycled in a southwest-verging accretionary complex ahead of which flysch was deposited in a flexural foreland basin. The system prograded southwards until the Late Eocene collisional stage, when the continental Norfolk ridge entered the convergence zone and blocked it. At this point the autochthonous and parautochthonous sedimentary cover and overlying flysch of northern New Caledonia was thrust over the younger flysch to the south to form a newly defined allochthonous unit, the ‘Montagnes Blanches’ nappe, that is systematically intercalated between the flysch and the obducted ophiolite units throughout Grande Terre.

Anabar-Lena Composite Tectono-Sedimentary Element, Northern East Siberia

2021 ◽  
pp. M57-2021-29
Author(s):  
A.K. Khudoley ◽  
S.V. Frolov ◽  
G.G. Akhmanov ◽  
E.A. Bakay ◽  
S.S. Drachev ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Oil And Gas ◽  
Foreland Basin ◽  
Early Carboniferous ◽  
Passive Margin ◽  
Source Rocks ◽  
East Siberia ◽  
Lena River ◽  
Petroleum Systems ◽  
Intracratonic Basin

AbstractAnabar-Lena Composite Tectono-Sedimentary Element (AL CTSE) is located in the northern East Siberia extending for c. 700 km along the Laptev Sea coast between the Khatanga Bay and Lena River delta. AL CTSE consists of rocks from Mesoproterozoic to Late Cretaceous in age with total thickness reaching 14 km. It evolved through the following tectonic settings: (1) Meso-Early Neoproterozoic intracratonic basin, (2) Ediacaran - Early Devonian passive margin, (3) Middle Devonian - Early Carboniferous rift, (4) late Early Carboniferous - latest Jurassic passive margin, (5) Permian foreland basin, (6) Triassic to Jurassic continental platform basin and (7) latest Jurassic - earliest Late Cretaceous foreland basin. Proterozoic and lower-middle Paleozoic successions are composed mainly by carbonate rocks while siliciclastic rocks dominate upper Paleozoic and Mesozoic sections. Several petroleum systems are assumed in the AL CTSE. Permian source rocks and Triassic sandstone reservoirs are the most important play elements. Presence of several mature source rock units and abundant oil- and gas-shows (both in wells and in outcrops), including a giant Olenek Bitumen Field, suggest that further exploration in this area may result in economic discoveries.

Neotethyan evolution of eastern Greece (Pagondas Mélange, Evia island) inferred from radiolarian biostratigraphy and the geochemistry of associated extrusive rocks

2001 ◽  
Vol 138 (3) ◽  
pp. 345-363 ◽  
Author(s):  
TANIEL DANELIAN ◽  
ALASTAIR H. F. ROBERTSON
Keyword(s):  
Shallow Water ◽  
Carbonate Platform ◽  
Ocean Basin ◽  
Passive Margin ◽  
Late Triassic ◽  
Geochemical Data ◽  
Chemical Compositions ◽  
Similar Chemical ◽  
Thrust Sheets ◽  
Age Range

This paper presents new radiolarian biostratigraphic and igneous/metamorphic geochemical data for a Mesozoic volcanic–sedimentary mélange on the island of Evia (Euboea or Evvoia), eastern Greece. This mélange includes dismembered thrust sheets and blocks of radiolarian chert and basalt. Biostratigraphic age data show that radiolarites interbedded with basalt-derived, coarse clastic sediments near the base of a coherent succession were deposited in Middle and Late Triassic time (Late Ladinian–Carnian, Norian?). Geochemical evidence shows that associated extrusive rocks, of inferred Triassic age, range from ‘enriched’ alkaline basalts, to ‘transitional’ basalts, and more ‘depleted’ mid-ocean ridge-type basalts. Amphibolite facies meta-basalts from the metamorphic sole of the over-riding Evia ophiolite exhibit similar chemical compositions. Both the basalts and the meta-basalts commonly show an apparent subduction-related influence (e.g. relative Nb depletion) that may have been inherited from a previous subduction event in the region. The basalts are interpreted to have erupted during Middle–Late Triassic time (Late Ladinian–Carnian), related to initial opening of a Neotethyan ocean basin adjacent to a rifted continental margin. Radiolarites located stratigraphically higher in the coherent succession studied are dated as Middle Jurassic (Late Bathonian–Early Callovian). Similar-aged radiolarites are depositionally associated with ophiolitic rocks (including boninites), in some other areas of Greece and Albania. During initial ocean basin closure (Bajocian–Bathonian) the adjacent shallow-water carbonate platform (Pelagonian zone) disintegrated to form basins in which siliceous sediments were deposited and highs on which shallow-water carbonates continued to accumulate. This facies differentiation is seen as a response to crustal flexure as the Neotethyan ocean began to close. The over-riding Pagondas Mélange and other similar units in the region are interpreted as accretionary prisms related to subduction of Neotethyan oceanic crust in Middle–Late Jurassic time. These mélanges were emplaced, probably diachronously during Oxfordian–Kimmeridgian time, when the passive margin collapsed, creating a foredeep ahead of advancing thrust sheets of mélange and ophiolites.

Evolution of the Appalachian Laurentian margin: Lithoprobe results in western Newfoundland

1998 ◽  
Vol 35 (11) ◽  
pp. 1271-1287 ◽  
Author(s):  
John WF Waldron ◽  
Scott D Anderson ◽  
Peter A Cawood ◽  
Laurel B Goodwin ◽  
Jeremy Hall ◽  
...  
Keyword(s):  
Foreland Basin ◽  
Shear Zones ◽  
Passive Margin ◽  
Thrust Sheets ◽  
External Part ◽  
Laurentian Margin ◽  
Seismic Reflection Profiles ◽  
Seismic Reflections ◽  
Seismic Lines ◽  
Thermal Subsidence

The Humber Zone of the western Newfoundland Appalachians represents the early Paleozoic Laurentian margin established by Neoproterozoic rifting. After a period of passive margin thermal subsidence, Taconian deformation began in the Early Ordovician with westward thrusting. Subsequently, an extensive foreland basin developed beneath the Gulf of St. Lawrence. It records rapid Late Ordovician to Early Silurian subsidence; mid-Silurian erosion; and renewed Late Silurian to Devonian subsidence. The Humber Zone was traversed by Lithoprobe seismic reflection profiles. Within the external part of the orogen, seismic reflections in the upper crustal section appear more coherent where seismic lines are parallel to fold hinges. Some subhorizontal reflectors are interpreted as thrust sheets of shelf limestone, but others probably represent intrabasement structures. A group of moderately northwest-dipping reflections probably represents late extensional shear zones. On the Baie Verte Peninsula, low-angle reflections passing beneath the Baie Verte Line are probably also late extensional shears, possibly reactivating earlier thrusts. Tectonism in the Humber Zone probably began with attempted eastward subduction of the Laurentian margin. Deep burial of the margin, accompanied by eclogite-facies metamorphism, probably coincided with rapid subsidence in the foreland basin. Later Barrovian metamorphism was associated with cleavage development and east-directed shear, and with dextral oblique slip, in Baie Verte Peninsula. Later Silurian sinistral transpression with thrusting east of the Baie Verte Line was followed by dextral transpression to transtension. "Acadian" thrusting dominated the western margin of the orogen in the Devonian and possibly earliest Carboniferous.

scholarly journals Basin architecture and growth folding of the NW Zagros early foreland basin during the Late Cretaceous and early Tertiary

2011 ◽  
Vol 168 (1) ◽  
pp. 235-250 ◽  
Author(s):  
Eduard Saura ◽  
Jaume Vergés ◽  
Stéphane Homke ◽  
Eric Blanc ◽  
Josep Serra-Kiel ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Foreland Basin ◽  
Early Tertiary

scholarly journals U-Pb ZIRCON DATING OF MIDDLE EOCENE CLASTIC ROCKS FROM THE GERCUS MOLASSE, NE IRAQ: NEW CONSTRAINTS ON THEIR PROVENANCE, AND TECTONIC EVOLUTION

2021 ◽  
Vol 54 (1C) ◽  
pp. 1-15
Author(s):  
Nabaz Aziz
Keyword(s):  
Tectonic Evolution ◽  
Middle Eocene ◽  
Early Stage ◽  
Foreland Basin ◽  
Detrital Zircons ◽  
Passive Margin ◽  
Accretionary Complex ◽  
Depositional Sequence ◽  
Clastic Rocks ◽  
The North

The provenance of Middle Eocene clastic rock from the Gercus Molasse, NE Iraq was determined by detrital zircon (DZ) U-Pb geochronology. The Gercus Molasse in the Iraqi segment of the north-eastern Zagros Thrust Zone provides an ideal example of foreland system evolution with respect to the transition from passive margin to the accretionary complex terrene-flexural foreland basins. The DZ U-Pb age spectra from the Gercus Molasse suggest that the foreland sediments either influx from multiple provenances or are the result of recycling from the accretionary complex terrane. During pre-accretion, however, the radiolarite basin (Qulqula Radiolarite, 221 Ma) located along Arabian passive margin likely acted as an intermediate sediment repository for most or all of the DZ. Representative DZ U-Pb measurements revealed that the Gercus clastic rocks fall into several separable age population ranges of 92-102 (Albian-Cenomanian), 221 (Upper Triassic), 395-511 (Cambrian), 570- 645 (Neoproterozoic), 1111 (Mesoproterozoic), and lesser numbers of Paleoproterozoic (1622-1991 Ma) ages. The source of Proterozoic detrital Zircons is enigmatic; the age peaks at 1.1, 1.5, 1.6, and 1.9 Ga (Proterozoic) does not correspond to any known outcrops of Precambrian rocks in Iraq, and it may be useful to continue to search for such basement. The detrital zircons with age populations at 0.63–0.86 Ga probably originated from the Arabian-Nubian Shield. The age peak at 0.55 Ga correlates with Cadomian Magmatism reported from north Gondwana. The age peaks at ~0.4 Ga is interpreted to represent Gondwana rifting and the opening of Paleotethys. The youngest ages populations at 93 Ma indicate that fraction of DZ were transported directly from the contemporaneously active magmatic arc (Zagros Ophiolite segments). The paleogeography and tectonic evolution of the Neogene Zagros foreland basin were reconstructed and divided into two tectonic stages. The early stage is defined by the Campanian accreted terranes (i.e. orogenic wedge) form loads sufficient to produce flexural basin with a deepest part is situated next to the tip of the loads. This flexural basin is filled by the flysch clastics of the Maastrichtian– Early Eocene (i.e. referred to by the Tanjero-Kolosh flysch sequence). The late stage is marked by a synchronized modification of the clastics fill of the basin and changes in dip directions to compensate for the reduction of the load by both erosion and extension and the basin, therefore, was sealed by a shallowing upwards depositional sequence ending with the terrestrial Gercus Formation.

Geodynamic constraints deciphered from the petrology and geochemistry of the Late Cretaceous granitoids from Anafi island (Cyclades - Greece)

2021 ◽  
Author(s):  
Petros Koutsovitis ◽  
Konstantinos Soukis ◽  
Panagiotis Voudouris ◽  
Stylianos Lozios ◽  
Theodoros Ntaflos ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Mineral Chemistry ◽  
Crustal Assimilation ◽  
Corner Flow ◽  
Granitoid Magma ◽  
Thrust Sheets ◽  
Petrology And Geochemistry ◽  
Crystallization Conditions ◽  
Structural Levels ◽  
Temperature Crystallization

<p>In the Aegean region (Cyclades - Greece), the island of Anafi island comprises Late Cretaceous intermediate and felsic granitoids that intruded within exhumed HT/LP metamorphic sequences that include amphibolites, serpentinites and metasediments. The granitoids correspond to I-type arc-related rocks with calc-alkaline geochemical affinities. Variations in their petrography mineral chemistry and geochemical features are attributed to magma differentiation with removal of plagioclase and/or K-feldspar, but also amphibole and biotite. Differentiation processes of the upwelling granitoid magma included fractional crystallization accompanied with crustal assimilation, pointing to interaction with the overriding continental crust. Mineral chemistry and geochemical results display that the Anafi granitoids are highly comparable with the Late Cretaceous granitoids of East Crete and Donousa island suggesting that this magmatic activity was not a local event. Geothermometric results show relatively moderate temperature crystallization conditions (~790 °C) for the compositionally intermediate granitoids, which are and lower for the felsic granitoids (~630 °C). Geobarometric calculations suggest shallow intrusion conditions (~2.0-6.5 kbar), which corresponds to a depth of crystallization of ~12 ± 4 km.</p><p>The thrust sheets that overly the flysch constitute a subducted and metamorphosed oceanic sequence, that after the intrusion of the granitoids was exhumed from the Late Cretaceous to the Late Oligocene. These metamorphic units likely represent a part of the Pindos - CBU domain that was subducted at an earlier pre-Campanian stage. In the hydrated mantle wedge, incorporation of shallow level granitoids within metamorphic units was likely facilitated via corner flow intrusion mechanisms. Ongoing underplating of subducted material gradually brought the granitoids along with the host units to shallow structural levels and on top of the parautochtonous flysch.</p>

40Ar/39Ar thermochronometric constraints on the tectonic evolution of the Clachnacudainn complex, southeastern British Columbia

1999 ◽  
Vol 36 (12) ◽  
pp. 1989-2006 ◽  
Author(s):  
Maurice Colpron ◽  
Raymond A Price ◽  
Douglas A Archibald
Keyword(s):  
British Columbia ◽  
Late Cretaceous ◽  
Tectonic Evolution ◽  
Thermal Evolution ◽  
Hanging Wall ◽  
Closure Temperature ◽  
Widespread Distribution ◽  
Early Tertiary ◽  
Intrusive Rocks ◽  
Structural Levels

40Ar/39Ar thermochronometry from the Clachnacudainn complex indicates that the thermal evolution of the complex was controlled primarily by the intrusion of granitoid plutons in mid- and Late Cretaceous times. Hornblendes from the eastern part of the complex cooled below their Ar closure temperature (ca. 500°C) shortly after intrusion of the mid-Cretaceous plutons; those from the western part of the complex have latest Cretaceous cooling dates, indicating cooling of these hornblendes after intrusion of the leucogranite plutons at ca. 71 Ma. Micas from the southern Clachnacudainn complex exhibit a pattern of progressive cooling toward lower structural levels, where Late Cretaceous and younger intrusions occur. The occurrence of Late Cretaceous - Paleocene mica cooling dates in both the hanging wall and footwall of the Standfast Creek fault refutes the hypothesis that there has been significant Tertiary extensional exhumation of the Clachnacudainn complex along the Standfast Creek fault. Furthermore, the widespread distribution of Late Cretaceous - Paleocene mica cooling ages suggests that an important volume of Late Cretaceous - early Tertiary intrusive rocks must be present in the subsurface beneath the Clachnacudainn complex.

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