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MACROSCOPICAL AND MICROSCOPICAL EVIDENCES MAGMA MIXING/MINGLING TYPE INTERACTION IN KESTANBOL GRANITOID (SOUTH ÇANAKKALE), NORTHWEST ANATOLIA-TURKEY

AUTHOR/S: ŞAHIN, S. Y., GUNGOR, Y., GOKER, F.
Sunday 1 August 2010 by Libadmin2004

4th International Scientific Conference - SGEM2004, www.sgem.org, SGEM2004 Conference Proceedings/ ISBN: 954-918181-2, June 14-18, 2004, 3 - 14pp

ABSTRACT

Kestanbol granitoid, one of the post-collision granitoids outcropping in
Northwestern Anatolia, takes place as a pluton in the southern of Çanakkale that approximately N-S trending and within a great tectonic belt. This tectonic belt, named Sakarya Continent, is bordered with Intra Pontide Suture in the NorthAern part and Izmir-Ankara Suture in the Southern part. Kestanbol granitoid intruded into crustal meta-sedimentary rocks by hot-contact and it is surrounded by contact metamorphic aureole. Kestanbol granitoid have a contact relation with volcanic and volcanosedimentary
rocks formed in coeval plutonic rocks or younger ones.
Kestanbol granitoids is composed of monzonite, quartz monzonite, monzogranite
and granodiorite according to field and microscopical investigations. Due to
interaction of felsic and mafic magmas syn-plutonic dykes, magma mingling and
magma mixing processes are revealed in this pluton. It includes mafic magmatic
enclaves (MME) and some mixing texture under the microscopy. Medium-coarse
grained Kestanbol granitoids have commonly holocrystalline granular texture but
sometimes it displays porphyritic texture due to the presence of K-feldspar
megacrystalls. It includes plagioclase (An 8-14) + orthoclase + quartz + hornblende +
biotite minerals and sphene+apatite+zircon and opaque minerals as accessory
minerals. Mafic magmatic enclaves are darker than their host rocks and they are
composed of diorite, quartz diorite, monzodiorite and quartz monzodiorite. The
boundaries between MME and host rock commonly have sharp; seldom gradually
contacts. MMEs have generally microgranular but sometimes-porphyritic textures due
to the presence of plagioclase phenocrystalls. These enclaves are described as “composite enclaves” due to their different textures and rock-types. Surrounding
chilled margin zones of MMEs are darker than their host rocks. Porphyritic textures
are formed by plagioclase phenocrystalls and K-feldspar megacrystals that exist either
in the host rocks or their MMEs. MMEs are mostly ovoidal-ellipsoidal and rarely
cornered shaped. Some of them are elongated-ellipsoidal shaped. Size of long axises
of MMEs are ranging from centimeter to meter. Cause of these elongated shapes is
the intensive deformation of their host rocks. Mineralogically they are composed of
plagioclase (An 18-22) + hornblend + biotite + sphene + apatite + zircon and opaque
minerals. It rarely includes quartz, K-feldspar (ortoclase) and pyroxene. Acicular,
lath-shaped mafic minerals are seen along fine-grained marginal zone around of
MMEs.
Kestanbol granitoid includes some mixing textures such as antirapakivi, lathshaped
small plagioclase within large plagioclase, poicilitic K-feldspar and poicilitic
plagioclase, rarely acicular apatite, appinitic and sphene-plagioclase ocellar textures.
Also MMEs have some mixing textures such as commonly acicular apatite texture,
blade-shaped biotite, poicilitic K-feldspar/plagioclase texture, hornblende/biotite
zones in K-feldspar/plagioclase phenocrystals, Spongy cellular plagioclase and spike
zone in plagioclase and dissolution melting in plagioclase texture.

Key words: Kestanbol granitoid, magma mingling, magma mixing, mafic
magmatic enclave (MME)

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