In Northwest Anatolia,
widespread magmatism developed due to collision between Anatolide-Tauride
platform and Sakarya continent during Late Cretaceous-Early Tertiary period. The
granitoids in Biga Peninsula are products of post-collisional magmatism
following the convergence of the northern branch of Neotethyan Ocean and
developed in two different stages as Eocene and Oligo-Miocene. Eocene Karabiga,
Güreci, Kuşçayır and Dikmen granitoids are granite and diorite-granodiorite;
Oligo-Miocene Sarıoluk, Yenice, Kestanbol, Eybek, Evciler, Çamyayla and Alanköy
granitoids are diorite, granodiorite, monzonite and Q-monzonite in composition.
Metaluminous and peraluminous granitoids have similar geochemical variations
and exhibit post-collisional geochemical signatures. Trace element patterns are
almost similar to those observed in upper crust and GLOSS (Global Subducting
Sediment) patterns with depletion in high field strength (HFS) elements (Nb, Ta,
Ti, Zr, Hf). But, Oligo-Miocene
Sarıoluk, Yenice-Çakıroba, Kestanbol, Evciler, Çamyayla, Alanköy and Eocene
Karabiga, Güreci and Kuşçayır granitoids have higher Th and U contents relative
to upper crust and GLOSS. Dikmen, Yenice-Hamdibey, Yenice-Eskiyayla and Eybek
granitoids have lower Th content. Geochemical variations indicate that partial melting
and fractional crystallisation- crustal contamination processes are effective
in their genesis and evolution. Trace element ratios also indicate subduction
signatures in their genesis and Rb/Ba, Rb/Sr ratios suggest mantle melting
rather than crustal melting. Accordingly, post-collisional Biga Peninsula
granitoids were derived from a previously metasomatised lithospheric mantle source,
which was enriched during northward subduction and closure of the northern branch
of Neo-Tethys Ocean beneath the Sakarya continent, since variations in Rb, Cs,
Th, La and Sm reveal that lithospheric mantle was mesomatised by both aqueous
fluids and sediment melts.
Biga Peninsula Granitoid Aqeous fluids Sediment melt Metasomatism
This study was supported bythe General Directorate of Mineral Research and Exploration (MTA) in the framework of the “Mineralisations related to acidic magmatism” project. We are extremely grateful to Mineral Research and Exploration Department and MTA northwestern Anatolia Region Headquarters (Balıkesir). We extend our special appreciation to S. Meltem Kadınkız and Nezihe Gökçe for their contributions in petrographical investigations. We are also grateful to Prof. Dr. Ahmet Gökçe and another anonymous reviewers for their constructive criticism and contributions to the final form of the manuscript.
In Northwest Anatolia, widespread magmatism developed due to collision between Anatolide-Tauride platform and Sakarya continent during Late Cretaceous-Early Tertiary period. The granitoids in Biga Peninsula are products of post-collisional magmatism following the convergence of the northern branch of Neotethyan Ocean and developed in two different stages as Eocene and Oligo-Miocene. Eocene Karabiga, Güreci, Kuşçayır and Dikmen granitoids are granite and diorite-granodiorite; Oligo-Miocene Sarıoluk, Yenice, Kestanbol, Eybek, Evciler, Çamyayla and Alanköy granitoids are diorite, granodiorite, monzonite and Q-monzonite in composition. Metaluminous and peraluminous granitoids have similar geochemical variations and exhibit post-collisional geochemical signatures. Trace element patterns are almost similar to those observed in upper crust and GLOSS (Global Subducting Sediment) patterns with depletion in high field strength (HFS) elements (Nb, Ta, Ti, Zr, Hf). But, Oligo-Miocene Sarıoluk, Yenice-Çakıroba, Kestanbol, Evciler, Çamyayla, Alanköy and Eocene Karabiga, Güreci and Kuşçayır granitoids have higher Th and U contents relative to upper crust and GLOSS. Dikmen, Yenice-Hamdibey, Yenice-Eskiyayla and Eybek granitoids have lower Th content. Geochemical variations indicate that partial melting and fractional crystallisation- crustal contamination processes are effective in their genesis and evolution. Trace element ratios also indicate subduction signatures in their genesis and Rb/Ba, Rb/Sr ratios suggest mantle melting rather than crustal melting. Accordingly, post-collisional Biga Peninsula granitoids were derived from a previously metasomatised lithospheric mantle source, which was enriched during northward subduction and closure of the northern branch of Neo-Tethys Ocean beneath the Sakarya continent, since variations in Rb, Cs, Th, La and Sm reveal that lithospheric mantle was mesomatised by both aqueous fluids and sediment melts.
Birincil Dil | İngilizce |
---|---|
Konular | Mühendislik |
Bölüm | Makaleler |
Yazarlar | |
Yayımlanma Tarihi | 27 Aralık 2019 |
Yayımlandığı Sayı | Yıl 2019 |
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