Sivas-Divriği Demir Yatağı Kireçtaşı-Ofiyolit-Granitoyid Üçlü Dokanağında Flogopit Oluşumları
Küçük Resim Yok
Tarih
2016
Yazarlar
Hüseyin Yalçın
Ömer Bozkaya
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Güneş Ofiyoliti'ne ait ultramafik kayaçlarda belirlenen bozuşma mineralleri serpantinleşme-öncesi, -sırası ve -sonrası olmak üzere üç ana gruba ayrılmıştır. Bunlardan serpantinleşme-öncesi minerallerden flogopit; ofiyolitik dizilimin oluşumu ile eşzamanlı mika-peridoditlerin ana bileşenlerinden birisidir. Sonraki bozuşmalardan lisfenitleşme ve pirometasomatizma, flogopitlerin tane boyunun artmasına ve belirli zonlarda birikmesine; yer yer karışık tabakalı flogopit-vermikülit (P-V) ve vermikülit dönüşümlerine neden olmuştur. Serpantinleşme-sırasında gelişen bozuşmalar koyu ve açık renkli minerallerin farklı kil ve/veya fillosilikat minerallerine dönüşümüdür. Serpantinleşme-sonrası bozuşma lisfenitleşme olup; başlıca ofikarbonat (yaygın kalsit ve dolomit; ender siderit ve hidrotalsit), ofioksit-hidroksit (hematit, götit, pirit, markasit, brusit) ve yer yer ofisilikat (kuvars) minerallerinin oluşumunu kapsamaktadır. Pirometasomatik kayaçlarda metasomatizma ürünlerini flogopit, aktinolit, epidot, yohansenit, skapolit, şörl ve Fe-mineralleri (manyetit, hematit, pirit, markasit); kalıntı birincil magmatik fazları ise piroksen ve feldispatlar oluşturmaktadır. Divriği flogopitleri; teorik flogopit-biyotit serisi uç üyelerinin oksit bileşimlerinden kısmen farklılık göstermektedir. Flogopitlerin biyotit bileşeni düşük olup, ortalama birim hücre bileşimine göre; Fe-Al flogopit olarak adlandırılmıştır. Ultramafik-ana kayaçlı P-V'in ana bileşeni Mg olup; kısmen Fe'ce zengin ve Al'ca fakirdir. Tetrahedral ve oktahedral Fe sübstitüsyonlara sahip serpantinler Fe-lizarditi işaret etmektedir. Divriği yöresindeki fillosilikat minerallerinin toplam eser element derişimi serpantin-flogopit-P-V yönünde azalmakta, buna karşın nadir toprak element içerikleri artmaktadır. ?18O ve ?D değerleri (SMOW) flogopitler için ? +10.6-11.8 ve ? -64 - -102, P-V için ? +14.2 ve ? -121, serpantin için ? +14.4 ve ? -129 olarak belirlenmiştir. ?18O ve ?D değerlerine göre; flogopitler hipojen ve süperjen alanda; buna karşın P-V ve serpantin ise kaolinit yüzeysel bozunma çizgisinin altında yer almaktadır. Granitik su minimum izotopik değerine göre flogopit için ~ 130-150 °C ve P-V için ~ 100 °C oluşum sıcaklıkları elde edilmiştir. Ayrıca, duraylı izotop verileri, serpantinleşme, flogopitleşme ve vermikülitleşmenin birbirini izleyen farklı süreçler ile oluştuğuna işaret etmektedir.
Alteration minerals determined in the ultramafic rocks of Güneş Ophiolite were divided into three main groups as pre-, syn- and post-serpentinization. Of these, phlogopite from pre-serpentinization minerals is one of the main components of mica-peridotites and is contemporaneous with the formation of the ophiolitic sequence. Listwaenitization and pyrometasomatism from later alterations caused an increase in grain size and accumulation of phlogopites in certain zones and also mixed-layer phlogopite-vermiculite (P-V) and vermiculite transformations in local. Syn-serpentinization alterations cover the conversions from felsic and mafic minerals to various clay and/or phyllosilicates. Post-serpentinization alteration covers the occurrences of ophicarbonate (commonly calcite and dolomite, rarely siderite and hydrotalcite), ophioxide-hydroxide (hematite, goethite, pyrite, marcasite and brucite) and locally ophisilicate (quartz) that refers to listwaenitization. Phlogopite, actinolite, epidote, johannsenite, scapolite, schorl and Fe-minerals (magnetite, hematite, pyrite, marcasite) form of the products of metasomatism in the pyrometasomatic rocks, and pyroxene and feldspar are residual primary magmatic phases. Divriği phlogopites differ partly in respect to end-member of theoretical oxide compositions of phlogopite-biotite series. Biotite component of phlogopites is low (8-14 %) and they are called as Fe-Al phlogopite according to their average unit-cell composition. The main cation of P-V in the ultramafic-hosted rocks is Mg and this mineral is partially rich in Fe and poor in Al. Serpentines have tetrahedral and octahedral Fe substitutions which indicate Fe-lizardite. The concentrations of total trace element in the phyllosilicate minerals decrease from serpentine-phlogopite to P-V, whereas their rare earth element contents increase in the same direction in the Divriği area. ?18O and ?D values (SMOW) are determined as ? +10.6-11.8 and ? -64 - -102 for phlogopites, ? +14.2 and ? -121 for P-V, and ? +14.4 and ? -129 for serpentine. Phlogopites are plot hypogene and supergene fields, but P-V and serpentine are found under kaolinite weathering line on the basis of ?18O and ?D values. Formation temperatures as ~ 130-150 °C for phlogopite and ~ 100 °C for P-V are obtained on the comparison of minimum isotopic value of granitic water. Additionally, stable isotopic values showed that serpentinization, phlogopitization and vermiculitization formed with different subsequent processes.
Alteration minerals determined in the ultramafic rocks of Güneş Ophiolite were divided into three main groups as pre-, syn- and post-serpentinization. Of these, phlogopite from pre-serpentinization minerals is one of the main components of mica-peridotites and is contemporaneous with the formation of the ophiolitic sequence. Listwaenitization and pyrometasomatism from later alterations caused an increase in grain size and accumulation of phlogopites in certain zones and also mixed-layer phlogopite-vermiculite (P-V) and vermiculite transformations in local. Syn-serpentinization alterations cover the conversions from felsic and mafic minerals to various clay and/or phyllosilicates. Post-serpentinization alteration covers the occurrences of ophicarbonate (commonly calcite and dolomite, rarely siderite and hydrotalcite), ophioxide-hydroxide (hematite, goethite, pyrite, marcasite and brucite) and locally ophisilicate (quartz) that refers to listwaenitization. Phlogopite, actinolite, epidote, johannsenite, scapolite, schorl and Fe-minerals (magnetite, hematite, pyrite, marcasite) form of the products of metasomatism in the pyrometasomatic rocks, and pyroxene and feldspar are residual primary magmatic phases. Divriği phlogopites differ partly in respect to end-member of theoretical oxide compositions of phlogopite-biotite series. Biotite component of phlogopites is low (8-14 %) and they are called as Fe-Al phlogopite according to their average unit-cell composition. The main cation of P-V in the ultramafic-hosted rocks is Mg and this mineral is partially rich in Fe and poor in Al. Serpentines have tetrahedral and octahedral Fe substitutions which indicate Fe-lizardite. The concentrations of total trace element in the phyllosilicate minerals decrease from serpentine-phlogopite to P-V, whereas their rare earth element contents increase in the same direction in the Divriği area. ?18O and ?D values (SMOW) are determined as ? +10.6-11.8 and ? -64 - -102 for phlogopites, ? +14.2 and ? -121 for P-V, and ? +14.4 and ? -129 for serpentine. Phlogopites are plot hypogene and supergene fields, but P-V and serpentine are found under kaolinite weathering line on the basis of ?18O and ?D values. Formation temperatures as ~ 130-150 °C for phlogopite and ~ 100 °C for P-V are obtained on the comparison of minimum isotopic value of granitic water. Additionally, stable isotopic values showed that serpentinization, phlogopitization and vermiculitization formed with different subsequent processes.
Açıklama
Anahtar Kelimeler
Jeoloji, Yerbilimleri, Ortak Disiplinler
Kaynak
Türkiye Jeoloji Bülteni
WoS Q Değeri
Scopus Q Değeri
Cilt
59
Sayı
1
