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Glass and mineral chemistry of northern central Indian ridge basalts: Compositional diversity and petrogenetic significance

หน่วยงาน National Institute Of Oceanography (NIO), India

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ชื่อเรื่อง : Glass and mineral chemistry of northern central Indian ridge basalts: Compositional diversity and petrogenetic significance
นักวิจัย : Ray, Dwijesh , Banerjee, R. , Iyer, S.D. , Basavalingu, B. , Mukhopadhyay, S.
คำค้น : petrogenesis , crystallization , mineral composition , mid-ocean ridges
หน่วยงาน : National Institute Of Oceanography (NIO), India
ผู้ร่วมงาน : -
ปีพิมพ์ : 2552
อ้างอิง : Acta Geologica Sinica, vol.83(6); 1122-1135 , http://drs.nio.org/drs/handle/2264/3472
ที่มา : -
ความเชี่ยวชาญ : -
ความสัมพันธ์ : -
ขอบเขตของเนื้อหา : -
บทคัดย่อ/คำอธิบาย :

The glass and mineral chemistry of basalts examined from the northern central Indian ridge (NCIR) provides an insight into magma genesis around the vicinity of two transform faults: Vityaz (VT) and Vema (VM). The studied mid-ocean ridge basalts (MORBs) from the outer ridge flank (VT area) and a near-ridge seamount (VM area) reveal that they are moderately phyric plagioclase basalts composed of plagioclase (phenocryst [An sub(60-90)] and groundmass [An sub(35-79)]), olivine (Fo sub(81-88)), diopside (Wo sub(45-51), En sub(25-37), Fs sub14-24)), and titanomagnetite (FeO sub(t) approx. 63.5 wt% and Ti0 sub(2) approx. 22.69 wt%). The whole-rock composition of these basalts has similar Mg [mole Mg/mole(Mg+Fe sup(2+))] (VT basalt: approx. 0.56-0.58; VM basalt: approx. 0.57), but differ in their total alkali content (VT basalt: approx. 2.65; VM basalt: approx. 3.24). The bulk composition of the magma was gradually depleted in MgO and enriched in FeO sub(t), Ti0 sub(2), P sub(2) O sub(5), and Na sub(2)0 with progressive fractionation, the basalts were gradually enriched in Y and Zr and depleted in Ni and Cr. In addition, the Sigma REE of magma also increased with fractionation, without any change in the (La/ Yb) sub(N) value. Glass from the VM seamount shows more fractionated characters (Mg: 0.56-0.57) compared to the outer ridge flank lava of the VT area (Mg: 0.63-0.65). This study concludes that present basalts experienced low-pressure crystallization at a relatively shallow depth. The geochemical changes in the NCIR magmas resulted from fractional crystallization at a shallow depth. As a consequence, spinel was the first mineral to crystallize at a pressure >10 kbar, followed by Fe-rich olivine at <10 kbar pressure

บรรณานุกรม :
Ray, Dwijesh , Banerjee, R. , Iyer, S.D. , Basavalingu, B. , Mukhopadhyay, S. . (2552). Glass and mineral chemistry of northern central Indian ridge basalts: Compositional diversity and petrogenetic significance.
    : National Institute Of Oceanography (NIO), India.
Ray, Dwijesh , Banerjee, R. , Iyer, S.D. , Basavalingu, B. , Mukhopadhyay, S. . 2552. "Glass and mineral chemistry of northern central Indian ridge basalts: Compositional diversity and petrogenetic significance".
    : National Institute Of Oceanography (NIO), India.
Ray, Dwijesh , Banerjee, R. , Iyer, S.D. , Basavalingu, B. , Mukhopadhyay, S. . "Glass and mineral chemistry of northern central Indian ridge basalts: Compositional diversity and petrogenetic significance."
    : National Institute Of Oceanography (NIO), India, 2552. Print.
Ray, Dwijesh , Banerjee, R. , Iyer, S.D. , Basavalingu, B. , Mukhopadhyay, S. . Glass and mineral chemistry of northern central Indian ridge basalts: Compositional diversity and petrogenetic significance. : National Institute Of Oceanography (NIO), India; 2552.