M.Sc. Tezi Görüntüleme

Student: Ahmet Dündar ŞEN
Supervisor: Doç. Dr. Orhan KARSLI
Department: Jeoloji Mühendisliği
Institution: Graduate School of Natural and Applied Sciences
University: Karadeniz Technical University, Turkey
Title of the Thesis: Mineralogical and Petrographical Investigation of Peridotitic Rocks From Harmancık Area (NE-Turkey, Bursa)
Level: M.Sc.
Acceptance Date: 30/1/2008
Number of Pages: 93
Registration Number: i1880
Summary:

      Whole rock major and trace element abundances and mineral phases of rock samples

from Harmancik, NW-Turkey are investigated to understand the formation of the ultramafic

      rocks which are supposed to be remnants of lithosphere of Neotethys Ocean.

MgO concentrations correlated negatively with SiO2, Al2O3, CaO, V, Sc, Yb and Lu.

      Al2O3 and CaO abundances are between 0.75-2.21 and 0.01-2.31 wt%, respectively and

increase with the increasing of clinopyroxene abundances.

      Olivine compositions range from Fo0.89 to Fo0.92 and show no chemical zoning. NiO

contents vary between 0.27 and 0.53 wt.%, and MnO contents reach up to 0.20 wt.%,

      indicating compositions similar to mantle olivine. Orthopyroxene has high Mg# (0.89-0.92)

and contains thin exsolution lamellae of clinopyroxene in some cases. Composition range

      between En86–91 Wo0–5 and Fs8–11, with low content of CaO (0.23–2.65 wt.%). Al2O3

concentrations show a wide variation between 1.47 and 4.95 wt.%. The Al2O3 contents in

      clinopyroxene vary between 1.88 and 6.09 wt.% and Cr2O3 contents between 0.45 and 1.27

wt.% with a Mg# comprised in the range of 0.90 and 0.95. They also contain up to 0.17 wt.%

      TiO2 and 0.64 wt.% Na2O.

Spinel grains are generally rich in Al, with the Cr# and Mg# ranging from 0.18 to

      0.56, and 0.5 to 0.79 respectively. Mg# of spinel is usually higher in clinopyroxene-rich

harzburgite than those of more depleted harzburgite and inversely correlated with the Cr#.

      Whole rock MgO and V concentrations, as well as mineral chemistry imply that these

rocks formed by different degrees of partial melting (%5-25). The clinopyroxene rich samples

      have higher REE abundances than those of clinopyroxene poor ones and all samples are

depleted with respect to chondrite showing convex-downward patterns. Mineral chemistry

      and whole rock abundances, as well as lack of abundant chromite deposits in the investigated

area, reflect that ultramafic rocks of Harmancik are similar to the abyssal peridotites and have

      not been affected intensively by percolating melt if SSZ origin is considered for the formation

of these rocks.

      Key Words: NW-Turkey, Harmancik (Bursa), Harzburgite, Supra Subduction Zone, Partial

Melting