Yolindi Cu-Fe skarn deposit, Gönen District, Balikesir Province, Turkeyi

Regional Level Types
Yolindi Cu-Fe skarn deposit	Deposit
Gönen District	District
Balikesir Province	Province
Turkey	Country

The Upper Paleozoic Kalabak Group, which comprises Torasan Formations, Yolindi metagranodiorite, and Sazak Formations, and the Triassic Karakaya Complex, constitute the area. The Early Miocene Hallaçlar volcanics and Early Miocene Şaroluk granitoids intruded into these rocks. Below is a quick summary of these significant lithostratigraphic units.
The Kalabak Group is the basement of the Sakarya Zone, which is a distinct tectonic unit. It is mostly made up of rocks that have been subjected to low-grade metamorphism. It was classified into two formations, with the Torasan Formation being the lowermost unit and the Sazak Formation representing the uppermost unit. The Torasan Formation is composed of epiclastic rocks that have undergone low-grade metamorphism. On the other hand, the Sazak Formation includes pyroclastic lithologies. The presence of metagranitic rocks that overlap, notably with the Torasan Formation, is an uncommon aspect of the Kalabak Group, known as the Yolinidi Metagranodiorite. The Upper Paleozoic Torasan Formation (Pzt) is known as Torasan metamorphic rocks by Okay, et al. It is located in the western part of the study area, around Yolindi village and Bıçkı and Baltaoluk hill. It is primarily composed of phyllites and muscovite-, biotite-, talc-, tremolite-, and chlorite-schists and their tuffs, with hornfels, metasandstone, and metasiltstone metamorphosed under low-to medium-grade metamorphic conditions. The phyllite and schists of the Torasan Formation, as well as its tuffs, are generally gray and greenish yellow in color, having foliation. Within the phyllites, serpentinized peridotites (Pzts), talc-antigorite schists, and marble members (Pztm) have scattered as blocks and lenses. A well-developed foliation of muscovite, biotite, and quartz with opaque minerals characterizes the fine-grained texture of phyllite. Biotite schists are distinguished by their schistose texture and mostly include biotite and quartz with a few opaque minerals. Actinolite hornfels are a contact metamorphic rock that include actinolite and quartz with clinozoisite, clinopyroxene, and opaque minerals. The serpentinites in these lenses, which have undergone low-grade metamorphism, are made up of antigorite with chlorite, clinopyroxene remnants, and less common opaque minerals. Marble and recrystallized limestone, on the other hand, are fine-grained and compact boulders with a white-gray tint, forming lenses 1–40 m thick and spanning thicknesses of 3–10 m, composed mainly of calcite. Yolindi metagranitoids (Pzy), on the other hand, are distinguished by brownish, medium-grained, significantly altered biotite gneiss, granitic porphyry, and metagranodiorite with directional textures and rare intrusions of dacitic and aplitic dykes. Their U-Pb zircon SHRIMP and LA-ICP-MS dating gave Early Middle Devonian ages. As well, their considerable outcrops may be seen to the north of the study area, towards Yolindi village. They are usually tectonically bounded on the western side by the Torasan Formation and unconformably covered on the eastern side by the Karakay Formation, extending in a NE-SW direction. Biotite gneiss is characterized by the presence of mineral bands that are often differentiated into distinct light and dark bands. Biotite is a significant constituent in this rock with quartz, sericitized plagioclase, and some opaque minerals. However, altered granodiorite porphyry comprises phenocrysts of sericitized plagioclase embedded in a groundmass of fine-grained kaolinitized feldspar, quartz, and opaque minerals. Sericitized plagioclase, quartz, biotite, and opaque minerals make up metagranodiorite. The Sazak Formation, which overlaps the Torasan Formation in the north of the study area, has a steady increase in tuff levels. It is made up of greenish fine-grained, well-foliated basic metatuffs, metavolcanites, tremolite-actinolite schist, and marble.

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