Tectonic significance of Late Ordovician granitic magmatism and clastic sedimentation on the northern margin of Gondwana (Tavşanlı
Zone, NW Turkey)
Zeynep Özbey
Timur Ustaömer
Alastair H. F. Robertson
P. Ayda Ustaömer
10.6084/m9.figshare.3453149.v1
https://geolsoc.figshare.com/articles/dataset/Tectonic_significance_of_Late_Ordovician_granitic_magmatism_and_clastic_sedimentation_on_the_northern_margin_of_Gondwana_Tav_anl___Zone_NW_Turkey_/3453149
<p>Metasedimentary schists and a small crosscutting metagranite underlie a Mesozoic metamorphosed carbonate platform within the
regional Anatolide tectonic belt of northern Turkey. These lithologies are inferred to have formed part of the northern margin
of Gondwana during the Palaeozoic. Immobile element geochemistry suggests that the country rock metasediments were derived
from upper continental crust and arc-type magmatic rocks. Major and trace element analyses of the metagranite indicate affinities
with upper continental crust or a continental margin magmatic arc. Tectonic discrimination of the metagranite is consistent
with a rift or post-collisional setting. Niobium depletion relative to Ce on primitive mantle-normalized spidergrams suggests
a subduction influence, possibly inherited from Late Precambrian (Cadomian) arc magmatism. Ion microprobe U–Pb dating of zircons
from the metagranite yielded a crystallization age of 446 ± 8 Ma (Late Ordovician). An inherited core gave a concordant age
of <em>c</em>. 578 Ma, consistent with Cadomian or Pan-African basement. Regional comparisons indicate that the Palaeozoic lithostratigraphy
is similar to that of the Taurides (Gondwana) rather than the Pontides (Laurasia). We infer Mid- to Late Ordovician crustal
extension along the north Gondwana margin, followed by spreading of Palaeotethys. The entire stratigraphy experienced high-pressure/low-temperature
metamorphism during Late Cretaceous closure of the İzmir–Ankara–Erzincan ocean.
</p>
2016-06-21 11:10:44
Tectonic discrimination
country rock metasediments
crosscutting metagranite
crystallization age
Cadomian
Cretaceous closure
Metasedimentary schists
Gondwana margin
trace element analyses
Ordovician crustal extension
Anatolide tectonic belt
Tectonic significance
Immobile element geochemistry
Niobium depletion
clastic sedimentation
arc magmatism
Ordovician granitic magmatism
margin magmatic arc
subduction influence
NW Turkey
578 Ma
Palaeozoic lithostratigraphy
Regional comparisons
carbonate platform
Geology