chemical characteristics of biotite from boroujerd granitoid complex (middle jurassic), western iran

نویسندگان

dariush esmaeily

department of geology, university college of sciences, university of tehran, tehran, iran reza maghdour-mashhour

department of geology, university college of sciences, university of tehran, tehran, iran amir ali tabbakh shabani

faculty of earth sciences, kharazmi university, tehran, iran

چکیده

biotite samples from different units of boroujerd granitoid complex (bgc) of the sanandaj-sirjan zone, western iran, have beenanalyzed by electron microprobe for major elements. biotite analyses from three units of quartzdiorite, granodiorite and monzograniteof bgc have their own distinct non-overlapping compositional fields in the annite – siderophyllite – phlogopite – eastonitequadrilateral (aspe), reflecting their host rock compositions. biotite from each rock unit has an increasing trend of al contents atalmost fixed fe/(fe+mg) values. in quartzdiorite it shows an approximately constant range of fe/(fe+mg) with a low to moderate alcontent from 2.5 to 3 atoms per formula unit (apfu). biotite from granodiorite exhibits a fairly wide range of al values reaching up to3.32 apfu, at fe/(fe+mg) from 0.6 to 0.7, whereas biotite from monzogranite have a relatively narrow range of fe/(fe+mg) and totalal values of limited range of 3.1 to 3.3 apfu. biotite compositions from these two latter units considered to be derived entirely fromcrustal material, characterized by a remarkable increase in total al at relatively high fe contents. biotite samples of quartzdioritesdefine a distinct and non-overlapping trend from those of granidiorites and monzogranites and hence interpreted to be derived from aparental magma with different composition. calculation of log(xmg/xfe) ranges from -0.09 to -0.02 and most of samples fromquartzdiorite fall within weakly and moderately contaminated i-type field of log(xf/xoh) versus log(xmg/xfe) diagram, whereasthe other two units, containing biotites with log(xmg/ xfe)< -0.21, classified as strongly contaminated reduced i-type. oxygenfugacity (log ƒo2) of -15.4 to -17.5 bars and ƒh2o of 200 to 560 bars were calculated for quartzdiorite. likewise, log (ƒo2) of –17.66bars and water fugacity (ƒh2o) of 400 and 700 bars were also calculated for granodiorite and monzogranites respectively. in thefeo*–mgo–al2o3 biotite discrimination diagram, biotite compositions from bgc are distributed between the calc-alkaline andperaluminous fields, i.e., biotite from the qaurtzdioritic rocks fall principally in the calc-alkaline field, whereas those from thegranodioritic and monzogranitic units plot almost exclusively in the peraluminous field consistent with their host rock nature

برای دانلود باید عضویت طلایی داشته باشید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Chemical characteristics of biotite from Boroujerd Granitoid complex (Middle Jurassic), Western Iran

Biotite samples from different units of Boroujerd Granitoid Complex (BGC) of the Sanandaj-Sirjan Zone, western Iran, have beenanalyzed by electron microprobe for major elements. Biotite analyses from three units of quartzdiorite, granodiorite and monzograniteof BGC have their own distinct non-overlapping compositional fields in the annite – siderophyllite – phlogopite – eastonitequadrilateral (...

متن کامل

chemical characteristics of biotite from boroujerd granitoid complex (middle jurassic), western iran

biotite samples from different units of boroujerd granitoid complex (bgc) of the sanandaj-sirjan zone, western iran, have beenanalyzed by electron microprobe for major elements. biotite analyses from three units of quartzdiorite, granodiorite and monzograniteof bgc have their own distinct non-overlapping compositional fields in the annite – siderophyllite – phlogopite – eastonitequadrilateral (...

متن کامل

Middle Jurassic Radiolarians from the Western Pacific

Middle Jurassic radiolarians have been recovered from the western Pacific for the first time. The oldest faunas are assigned to the middle and upper Tricolocapsa conexa Zone, indicating a Bathonian/Callovian age. The faunas contain more than 30 species and are characterized by an abundance of small nassellarians with a constricted distal end. The faunas compare well with Tethyan faunas, and are...

متن کامل

Petrology and geochemistry of Aligoodarz granitoid, Western Iran: implications for petrogenetic relation with Boroujerd and Dehno granitoids

The Aligoodarz granitoid occurs in Sanandaj-Sirjan Zone (SSZ), Western Iran. Tonalite, granodiorite and granite are the main rock types cropping out in the area. Comparison of Aligoodarz granitoid with Dehno and Boroujerd granitoids reveals several similarities in their chemical characteristics. Thus, the above mentioned granitoids can be assigned as a co-genetic magmatic suite, in which pluton...

متن کامل

Middle Jurassic plant macro and microfossils from Shahreza, South West Isfahan, Central Iran: Palaeoclimate influences

Jurassic deposits are discovered in the Shahreza area, southwest of Isfahan city, central Iran. They yield plant macrofossils belonging to 22 species assigned to 17 genera of various orders such as Equisetales, Filicales, Bennettitales, Cycadales, Ginkgoales and Coniferales. According to the occurrence of Annulariopsis simpsonii, Coniopteris hymenophylloides, Cladophlebis aktashensis, Nilssonia...

متن کامل

Late Jurassic salamandroid from western Liaoning, China.

A Jurassic salamander, Beiyanerpeton jianpingensis (gen. et sp. nov.), from a recently found site in western Liaoning Province, China is the earliest known record of Salamandroidea. As a Late Jurassic record of the group, it extends the range of the clade by ~40 Ma. The Late Jurassic taxon is neotenic and represented by exceptionally preserved specimens, including fully articulated cranial and ...

متن کامل

منابع من

با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید


عنوان ژورنال:
geopersia

جلد ۳، شماره ۱، صفحات ۶۹-۷۸

میزبانی شده توسط پلتفرم ابری doprax.com

copyright © 2015-2023