Mineralogy of the Kraubath-type magnesite deposits of the Khuzdar area, Balochistan, Pakistan

Yıl 2009, Cilt: 30 Sayı: 3, 169 - 180, 01.04.2009

Erum Bashır Shahid Naseem Shamim Ahmed Sheıkh Maria Kaleem

Öz

Mineralogical studies of the magnesite deposits in the Khuzdar District, Balochistan, Pakistan were made using the Xray diffraction (XRD) technique. These Kraubath-type magnesite deposits are hosted within serpentinized harzburgites, associated with Bela Ophiolite of Cretaceous age. The deposits occur as cryptocrystalline veins of stockwork-type, possessing botryoidal and bone habits. The ultramafic rocks of Bela Ophiolite were subjected to serpentinization. The hydrothermal fluids leached out Mg, Ca, Fe and other elements from the serpentinized rocks and finally carbonation of these ions resulted in the formation of their hydroxides and carbonates of different combinations to produce these deposits. The XRD analysis of the ores revealed a high magnesite content in association with artinite, brucite, huntite, Femagnesite, dolomite, calcite and Mg-calcite. Initially, at low temperatures and low partial pressure from carbon dioxide (PCO2), metastable hydroxides and carbonates are formed, and these are gradually converted into a stable magnesite phase. The low abundance of allied minerals reflects the relatively high temperature conditions and PCO2 that convert metastable minerals into their stable magnesite phase. The study revealed an increasing temperature and PCO2
from brucite through artinite, hydromagnesite, huntite, and dolomite to magnesite. Principal component analysis (PCA) and correlation matrix analysis were also utilized to reveal the genetic affiliation that existed between these minerals.

Anahtar Kelimeler

Balochistan, Khuzdar, Kraubath-type magnesite, mineralogy, Pakistan

Khuzdar Bölgesi (Belucistan, Pakistan)’ndeki Kraubath tipi manyezit yataklarının mineralojisi

Öz

Khuzdar Bölgesi (Belucistan, Pakistan)’ndeki manyezit yataklarının mineralojisi X-ışınları kırınım tekniğiyle araştırılmıştır. Kraubath tipi bu manyezit yatakları, Kretase yaşlı Bela ofiyolitleriyle ilişkili serpantinleşmiş harzburjitler içinde yer almaktadır. Bu çökeller, kriptokristalin damarlar ve botriyodal ve kemiksi. özelliklere sahip ağsı yatak şeklinde oluşmuşlardır. Bela ofiyolitik kayaçları serpantinleşmeye maruz kalmışlardır. Hidrotermal akışkanlarca taşınan Mg, Ca, Fe ve serpantinleşmiş kayalardan gelen diğer elementler ve sonuçta bu iyonların karbonatlaşması, bunların hidroksitlerinin oluşumuyla ve farklı bileşimlerdeki karbonatların bu çökelleri oluşturmasıyla sonuçlanmıştır. Cevherlerin X-ışınları kırınım analizleri; artinit, brusit, huntit, Fe-manyezit, dolomit, kalsit ve Mg-kalistle ilişkili yüksek manyezit içeriğinin varlığını göstermektedir. İlk olarak, düşük sıcaklıkta ve düşük kısmi karbondioksit (PCO2) basıncı altında, tedricen duraylı manyezit fazına dönüşen yarı-duraylı hidroksitler ve karbonatlar oluşmuştur. Yabancı minerallerin azlığı, göreceli olarak yüksek sıcaklık koşullarına ve yarı-duraylı mineralleri manyezit fazına dönüştüren PCO2’ye işaret etmektedir. Bu çalışma, artan sıcaklığı ve arinit, hidromanyezit, huntit, dolomitten itibaren brusitten PCO2 artışını göstermiştir. Ayrıca asal bileşen analizi (PCA) ve korelasyon matriksi analizi bu mineraller arasında mevcut olan kökensel ilişknin araştırılmasıi için kullanılmıştır

Anahtar Kelimeler

Belucistan, Khuzdar, Kraubath tipi manyezit, mineraloji, Pakistan

Kaynakça

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