High-temperature acid magmatic rocks from the Late Cretaceous suture zone between European plate and Adria microplate (Croatia)

2020 ◽  
Author(s):  
Petra Schneider ◽  
Dražen Balen
Keyword(s):  
High Temperature ◽  
Late Cretaceous ◽  
Suture Zone ◽  
Age Dating ◽  
Magma Source ◽  
Northwestern Part ◽  
Magmatic Complex ◽  
Magmatic Rocks ◽  
The Village ◽  
European Plate

<p>The Late Cretaceous magmatic rocks within the southwestern part of the Pannonian Basin basement (Croatia) occur in two areas: Voćin volcanic mass (VVM) at the northwestern part of Mt. Papuk (near town of Voćin, covering the area of ~10km<sup>2</sup>) and volcanic mass of Mt. Požeška Gora (PVM, area of ~30 km<sup>2</sup>). Both volcanic masses consist of basalts and rhyolites, and in lesser extent of pyroclastic material. Granite can be found it the PVM. Interconnection of this two masses and Late Cretaceous ages have been proposed based on the petrography and mineralogical features of previously studied samples and rather arguable data: K-Ar dating on basalts from VVM (~73−52 Ma) and Rb-Sr isochron age on granite and rhyolite from PVM (~72 Ma). The age has been recently refined with the zircon LA-ICP-MS age dating (~82 Ma), but the magma source of this bimodal formation, geotectonic position, setting and its regional importance still have not been explained in detail.</p><p>In order to conduct preliminary research, two localities with acid effusive rocks were sampled from the VVM (Rupnica geosite and Trešnjevica quarry), and three more from PVM (near the village of Vesela, Pakao Creek and the granite from quarry near the village of Gradski Vrhovci).</p><p>Acid rocks are characterized by a highly siliceous composition (up to 75 wt.% SiO<sub>2</sub>), enrichment in alkalies (high-K calc-alkaline towards to shoshonite series) and aluminium (peraluminous affinity), followed by high FeO<sub>T</sub>/(FeO<sub>T</sub>+MgO) ratios matching ferroan magmas. They classify as rhyolites or alkali-rhyolites/granite. Microelements including REE show that studied rocks have characteristics of A<sub>2</sub>-type of post-collisional/post-orogenic acid rocks, most common A-type of rocks formed during rifting caused by extension and thinning of continental crust. According to geotectonic classification diagrams, rocks from PVM show geochemical signature of volcanic arc, while VVM shows signature of within plate environment.</p><p>External zircon morphology seems to be uniform with prevailing J3−J5-type for rhyolites and D-type for granite and with average ratio of 2.2:1. Those types are characteristic for the high-temperature magmas (confirmed with the calculated Zr-saturation temperature of 850−930°C) originating from the lower crust or even upper mantle. Inclusions of hematite, F-apatite and anatase have been detected with Raman spectrometry in zircon from all samples, with the most significant findings of kumdykolite and kokchetavite inclusions detected in samples from Vesela and Gradski Vrhovci. Latter inclusions are metastable phases crystallized from enclosed melt and are indicators of a rapid cooling of the host magma.</p><p>According to the results presented here, acid rocks show rather uniform geochemistry, which speaks in favor of the early ideas of the unique magmatic complex, although today at the surface they are separated by ~35 km in distance. Those rocks show potential to be of great regional importance bearing new information about the evolution in the Late Cretaceous in the area of Sava Zone, a suture zone between Tisia Mega-Unit (European plate) and Adria microplate, which spatially and temporally marks the closure of the Neotethys Ocean.</p><p>Support by the Croatian Science Foundation (IP-2014-09-9541) is acknowledged.</p>

Closure of the Bangong–Nujiang Tethyan Ocean in the central Tibet: Results from the provenance of the Duoni Formation

2019 ◽  
Vol 89 (10) ◽  
pp. 1039-1054 ◽  
Author(s):  
Zhicai Zhu ◽  
Qingguo Zhai ◽  
Peiyuan Hu ◽  
Sunlin Chung ◽  
Yue Tang ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Suture Zone ◽  
The Tibetan Plateau ◽  
Tectonic History ◽  
Magmatic Rocks ◽  
Two Samples ◽  
Delta Sequence ◽  
History Of ◽  
Central Tibet

ABSTRACT The closure of the Bangong–Nujiang Tethyan Ocean (BNTO) and consequent Lhasa–Qiangtang collision is vital to reasonably understanding the early tectonic history of the Tibetan Plateau before the India-Eurasia collision. The timing of the Lhasa–Qiangtang collision was mainly constrained by the ophiolite and magmatic rocks in previous studies, with only limited constraints from the sedimentary rocks within and adjacent to the Bangong–Nujiang suture zone. In the middle segment of the Bangong–Nujiang suture zone, the Duoni Formation, consisting of a fluvial delta sequence with minor andesite interlayers, was originally defined as the Late Cretaceous Jingzhushan Formation and interpreted as the products of the Lhasa–Qiangtang collision during the Late Cretaceous. Our new zircon U-Pb data from two samples of andesite interlayers demonstrate that it was deposited during the latest Early Cretaceous (ca. 113 Ma) rather than Late Cretaceous. Systemic studies on the sandstone detrital model, heavy-mineral assemblage, and clasts of conglomerate demonstrate a mixed source of both Lhasa and Qiangtang terranes and ophiolite complex. Clasts of conglomerate contain abundant angular peridotite, gabbro, basalt, chert, andesite, and granite, and minor quartzite and gneiss clasts also exist. Sandstones of the Duoni Formation are dominated by feldspathic–lithic graywacke (Qt25F14L61 and Qm13F14L73), indicative of a mixture of continental-arc and recycled-orogen source origin. Detrital minerals of chromite, clinopyroxene, epidote, and hornblende in sandstone also indicate an origin of ultramafic and mafic rocks, while garnets indicate a metamorphosed source. Paleocurrent data demonstrate bidirectional (southward and northward) source origins. Thus, we suggest that the deposition of the Duoni Formation took place in the processes of the Lhasa–Qiangtang collision during the latest Early Cretaceous (∼ 113 Ma), and the BNTO had been closed by this time.

Collision and reactivation along the South Tianshan Orogen (NW China) through late Paleozoic to Mesozoic time

2021 ◽  
Author(s):  
Yigui Han ◽  
Guochun Zhao
Keyword(s):  
Continental Collision ◽  
Orogenic Belt ◽  
Late Paleozoic ◽  
Magma Source ◽  
The South ◽  
Nw China ◽  
Magmatic Rocks ◽  
Western Tianshan ◽  
Tarim Craton ◽  
South Tianshan

<p>The South Tianshan Orogenic Belt in NW China marks the suturing site between the Tarim Craton and the Central Asian Orogenic Belt (CAOB) during late Paleozoic-Mesozoic time. Despite numerous investigations, the amalgamation history along the South Tianshan Orogen remains controversial, especially on the timing and process of the final continental collision between the Tarim Craton and the Central Tianshan (CTS)-Yili Block. We inquire into this issue on the basis of a compiled dataset across the Tarim, South Tianshan and CTS-Yili regions, comprising elemental and isotopic data of magmatic rocks and radiometric ages of regional magmatism, detrital zircons, (ultra-)high pressure metamorphism and tectonothermal events. The data support a continental collision along the South Tianshan belt in 310-300 Ma, in accord with a contemporaneous magmatic quiescence and a prominent decrease of εNd(t) and εHf(t) values of magmatic rocks in the CTS region, and a main exhumation stage of (U)HP rocks in the South Tianshan region. The collisional orogeny along the South Tianshan have most likely been influenced by a mantle plume initiated at ca. 300 Ma underneath the northern Tarim Craton, as evidenced by temporal and spatial variations of geochemical proxies tracing magma source characteristics. The new model of plume-modified collision orogeny reconciles the absence of continental-type (U)HP rocks in the orogen and the insignificant upper-plate uplift during continental collision. In the mid-Triassic (ca. 240 Ma), the Chinese western Tianshan underwent intense surface uplift and denudation, as indicated by sedimentary provenance analysis and tectonothermal events. Paleocurrent and detrital zircon age data from Triassic strata in northern Tarim suggest a provenance change from a single source of the Tarim Craton to multiple sources including the CTS-Yili Block to the north and the Western Kunlun Orogen to the south. We suggest that the mid-Triassic uplifting in Chinese western Tianshan was an intracontinental orogeny caused by far-field effects of the collision between the Tarim Craton and the Qiangtang Block. This research was financially supported by NSFC Projects (41730213, 42072264, 41902229, 41972237) and Hong Kong RGC GRF (17307918).</p>

scholarly journals Geochemical-isotopic characteristics and K-Ar ages of magmatic rocks from Hundar valley, Shyok Suture Zone, Ladakh

1970 ◽  
Vol 5 (7) ◽  
pp. 18
Author(s):  
T Ahmad ◽  
S Sivaprabha ◽  
S Balakrishnan ◽  
NX Thanh ◽  
T Itaya ◽  
...  
Keyword(s):  
Suture Zone ◽  
Special Issue ◽  
Magmatic Rocks

DOI = 10.3126/hjs.v5i7.1229 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.18

Remains of Clidastes Cope, 1868, an unexpected mosasaur in the upper Campanian of NW Germany

2005 ◽  
Vol 84 (3) ◽  
pp. 213-220 ◽  
Author(s):  
M.W. Caldwell ◽  
C.G. Diedrich
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Vertebral Column ◽  
Gulf Coast ◽  
Anterior Part ◽  
Western Interior Seaway ◽  
Southern Sweden ◽  
Nw Germany ◽  
The Village ◽  
Upper Campanian

AbstractThe mosasaurine Clidastes sp. is recognised from cranial and post-cranial remains collected at four localities in NW Germany. Cranial material was found in pelagic turbiditic marls which crop out near the village of Beckum, while post-cranial skeletal elements were collected from sandy limestones exposed near the villages of Schöppingen, Coesfeld and Billerbeck. In stratigraphic order, the units producing these specimens of Clidastes are the Coesfeld, Baumberge and Beckum formations of late Campanian (Late Cretaceous) age. The cranial material comprises the anterior part of a skull and a single isolated tooth, while post-cranial bones comprise a few isolated vertebrae and a partial skeleton including forelimb bones and an articulated vertebral column. Clidastes is known to date from the western North Sea Basin (England), southern Sweden, as well as from North America (Western Interior Seaway and Gulf Coast).

2D Numerical Simulation of Intraoceanic Subduction during the Upper Jurassic Closure of the Vardar Tethys

2020 ◽  
Author(s):  
Nikola Stanković ◽  
Vesna Cvetkov ◽  
Vladica Cvetković
Keyword(s):  
Numerical Simulations ◽  
Late Cretaceous ◽  
Stokes Equations ◽  
Numerical Models ◽  
Upper Jurassic ◽  
Staggered Grid ◽  
Parameter Study ◽  
Ongoing Research ◽  
Magmatic Complex ◽  
Vardar Zone

<p>In this study we report interim results of our ongoing research that involves the application of numerical modeling for constraining the geodynamic conditions associated with the closure of the Vardar branch of the Tethys Ocean. The study is aimed at better understanding the ultimate fate of the Balkan ophiolites, namely at addressing the question whether these ophiolites represent relicts of an ocean that completely closed during Upper Jurassic/lowermost Cretaceous time (Vardar Tethys) or they also contain remnants of the ocean floor of a Late Cretaceous oceanic realm (Sava – Vardar) [Schmid et al., 2008].</p><p>In our numerical models we try to simulate a single intraoceanic subduction that commences in the Lower/Mid Jurassic and ends in the Lower Cretaceous, transitioning into oceanic closure processes and subsequent collision between Adria and Eurasia plates. These convergent-collision events should have led to the formation of ophiolite-like igneous rocks of the so-called Sava - Vardar zone.</p><p>A series of numerical simulations were performed with varying parameters. In the scope of our numerical simulations, the set of equations is solved: the continuity equation, the Navier-Stokes equations and the temperature equation. Marker in cell method was incorporated in solving this system with finite difference discretization of the equations on a staggered grid. To utilize this numerical method a thermo-mechanical code I2VIS [Gerya et al., 2000; Gerya & Yuen, 2003] was used for obtaining the final results. </p><p>Our actual 2D thermo-mechanical models cover the crust and the upper portion of the mantle with varying starting widths of the Vardar Ocean in the Lower Jurassic. The ocean is modeled with two segments: the western subducting slab and the eastern overriding slab. Slabs with different ages and thicknesses were used and the convergence rate is varied. The intraoceanic subduction is assumed to have been initiated along the mid oceanic ridge. Two continents (i.e. Adria and Eurasia) with different thicknesses of the continental lithosphere and crust are also modeled adjacent to a single oceanic realm between them.</p><p>The parameter study is in function of defining conditions under which the hypothesized scenario occurs. So far, we have succeeded in reproducing westward obduction onto the Adriatic margin, which is in accordance with the geological observations, i.e., with the top-west emplaced West Vardar ophiolites [see Schmid et al., 2008 for references]. However, our model is yet to produce sufficient amounts of back-arc extension along the Eurasian active margin and that is crucial for explaining the formation of the igneous provinces occurring within the Late Cretaceous Sava – Vardar zone and the Timok Magmatic Complex.</p>

scholarly journals Geochronology and Geochemistry of the Magmatic Rocks from Zedong Ophiolite, Eastern Yarlung-Zangbo Suture Zone, Tibet

2017 ◽  
Vol 91 (s1) ◽  
pp. 45-45
Author(s):  
Fahui XIONG ◽  
Jingsui YANG ◽  
Paul T. ROBINSON ◽  
Jian GAO ◽  
Lan ZHANG ◽  
...  
Keyword(s):  
Suture Zone ◽  
Magmatic Rocks ◽  
Yarlung Zangbo Suture Zone
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