GSTDTAP  > 地球科学
DOI10.1130/B31993.1
Postcollisional transition from subduction- to intraplate-type magmatism in the eastern Sakarya zone, Turkey: Indicators of northern Neotethyan slab breakoff
Dokuz, Abdurrahman1; Aydin, Faruk2; Karsli, Orhan3
2019-09-01
发表期刊GEOLOGICAL SOCIETY OF AMERICA BULLETIN
ISSN0016-7606
EISSN1943-2674
出版年2019
卷号131页码:1623-1642
文章类型Article
语种英语
国家Turkey
英文摘要

Postcollisional magmatism in the eastern Sakarya zone was recorded by voluminous basic volcanism and repeated plutonism during the early Cenozoic. The temporal and geochemical evolution of these magmatic rocks is important for understanding the possible geodynamic history of the Sakarya zone. Here, we investigated three representative plutons lying between the towns of Camlihemsin (Rize) and Ispir (Erzurum), Turkey. These are largely composed of medium-K gabbroic diorites (Marselavat Pluton), shoshonitic monzonites (Gullubag Pluton), and high-K granites (Ayder Pluton). We present whole-rock geochemistry, Ar-40/Ar-39 geochronology, and Sr, Nd, and Pb isotope analyses from the plutons to constrain the timing of variations in magmatism and source characteristics, and we provide a new approach to the proposed geodynamic models, which are still heavily debated. The Ar-40/Ar-39 geochronology reveals a cooling sequence from ca. 45 Ma for the Marselavat Pluton through ca. 41 Ma for the Giilliibag Pluton to ca. 40 Ma for the Ayder Pluton. Whole-rock geochemistry and Sr, Nd, Pb isotopes suggest that crustal contamination was not an important factor affecting magma compositions. Although there was no arc-related tectonic setting in the region during the middle Eocene, the Marselavat Pluton shows some subduction affinities, such as moderately negative Nb and Ta anomalies, and slightly positive Pb anomalies. These signatures were possibly inherited from a depleted mantle source that was modified by hydrous fluids released from the oceanic slab during Late Cretaceous subduction. Geochemical traces of the earlier subduction become uncertain in the Gullubag samples. They display ocean-island basalt-like multi-element profiles and Nb/Ta, Ce/Pb, and La/Ba ratios. All these point to a mantle source in which earlier subduction signatures were hybridized by the addition of asthenospheric melts. Melting of calc-alkaline crustal material, probably emplaced during the first phase of middle Eocene magmatism (Marselavat), led to the formation of granitic plutonism (Ayder Pluton). Our data in conjunction with early Eocene adakite-like rocks show that melt generation, as in the given sequence, was most probably triggered by breakoff of the northern Neotethyan oceanic slab, similar to 13 m.y. after the early Maastrichtian collision between the Sakarya zone and Anatolide-Tauride block, and continued until the end of the middle Eocene. A shallow-marine transgression occurred contemporaneously with the middle Eocene magmatism throughout the Sakarya zone. An extension in this magnitude seems unlikely to be the result of orogenic collapse processes only. The main cause of this extension was most probably related to the northward subduction of the southern Neotethys Ocean beneath the Anatolide-Tauride block. The result is a volumetrically larger amount of middle Eocene magmatism than that expected in response to slab breakoff.


领域地球科学
收录类别SCI-E
WOS记录号WOS:000483604100012
WOS关键词YUSUFELI-ARTVIN AREA ; NB-ENRICHED BASALTS ; HIGH-K VOLCANISM ; NE TURKEY ; U-PB ; LITHOSPHERIC MANTLE ; TRACE-ELEMENT ; CALC-ALKALINE ; WHOLE-ROCK ; ISOTOPE GEOCHEMISTRY
WOS类目Geosciences, Multidisciplinary
WOS研究方向Geology
引用统计
文献类型期刊论文
条目标识符http://119.78.100.173/C666/handle/2XK7JSWQ/186685
专题地球科学
作者单位1.Gumushane Univ, Dept Geol Engn, TR-29000 Gumushane, Turkey;
2.Karadeniz Tech Univ, Dept Geol Engn, TR-61080 Trabzon, Turkey;
3.Recep Tayyip Erdogan Univ, Dept Geol Engn, TR-53100 Rize, Turkey
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Dokuz, Abdurrahman,Aydin, Faruk,Karsli, Orhan. Postcollisional transition from subduction- to intraplate-type magmatism in the eastern Sakarya zone, Turkey: Indicators of northern Neotethyan slab breakoff[J]. GEOLOGICAL SOCIETY OF AMERICA BULLETIN,2019,131:1623-1642.
APA Dokuz, Abdurrahman,Aydin, Faruk,&Karsli, Orhan.(2019).Postcollisional transition from subduction- to intraplate-type magmatism in the eastern Sakarya zone, Turkey: Indicators of northern Neotethyan slab breakoff.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,131,1623-1642.
MLA Dokuz, Abdurrahman,et al."Postcollisional transition from subduction- to intraplate-type magmatism in the eastern Sakarya zone, Turkey: Indicators of northern Neotethyan slab breakoff".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 131(2019):1623-1642.
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