بررسی تاوایی گرانیت میلونیتی ده زمان بر اساس کرنش بلورهای فلدسپار

سودمند, زهرا; معدنی پور, سعید; نوزعیم, رضا

doi:10.52547/ijcm.30.3.447

بررسی تاوایی گرانیت میلونیتی ده زمان بر اساس کرنش بلورهای فلدسپار

نوع مقاله : مقاله پژوهشی

نویسندگان

¹ دانشگاه تربیت مدرس

² دانشگاه تهران

10.52547/ijcm.30.3.447

چکیده

گرانیت میلونیتی ده زمان در شمال غرب قطعه لوت (پهنه کاشمر-کرمان) و منطقه کوه سرهنگی واقع است. در این توده گرانیتی به سن پرکامبرین پسین (557-561 میلیون سال)، برگوارگی میلونیتی با راستای 120 درجه و شیب 80 درجه به سمت جنوب شرق به‌خوبی گسترش ‌یافته است. زاویه افتادگی خطواره کششی تا حدود 40 درجه به سمت جنوب شرق است. در این پژوهش، بزرگی تاوایی در گرانیت میلونیتی ده زمان بر اساس کرنش بلورهای فلدسپار بررسی شد. شواهد ریزساختاری آواریهای فلدسپاری نشاندهنده هم‌سویی برشها بهصورت راستالغز چپ‌گرد در منطقه است. شواهد ریزساختاری پورفیری آواریهای به نسبت شکل‌دار فلدسپار و همچنین بازتبلور دینامیکی از نوع مهاجرت مرزدانه بیانگر دمای دگرریختی حدود °C450 به‌صورت یک میلونیت درجه پایین تا متوسط هستند. عدد تاوایی این گرانیت میلونیتی بر اساس نتایج برآمده از کرنش بلورهای فلدسپار 8/0 برآورد شد که نشاندهنده غلبه مؤلفه برش ساده (60%) بر برش محض (40%) طی گسترش ساختار میلونیتی در شرایط ترا فشارشی است.

کلیدواژه‌ها

20.1001.1.17263689.1401.30.3.5.3

عنوان مقاله [English]

Kinematic vorticity analysis of the Deh Zaman mylonitic granite based on deformed feldspar grains

نویسندگان [English]

Soudmand ¹
Madanipour ¹
Nozaem ²

چکیده [English]

Deh-Zaman mylonitic granite is located northwest of the Lut Block (Kashmar-Kerman zone) in the northeastern part of Kuh-e-Sarhangi shear zone. In this granitic body (~557-561 Ma), mylonitic foliation with S62˚E/80NE attitude is very well developed. The mean pitch of stretching lineation is ~40 ˚ toward the southeast. The main purpose of this study is to quantify the vorticity number based on the strain of feldspar crystals. The microstructural evidence of the feldspar crystals indicates that the sense of shear is left-lateral strike-slip in the region. The presence of moderately euheadral porphyroclasts of feldspar with observed dynamic recrystallization of grain boundary migration type, indicates ~450°C deformation temperature that shows a low to medium grade mylonite. The vorticity number of this mylonite granite is estimated to be 0.8 based on the feldspar crystal strain. This indicates the predominance of simple shear component (60%) over pure shear (40%) and the development of mylonitic structure under transpression conditions.

کلیدواژه‌ها [English]

strain
vorticity
transpression
Deh Zaman mylonite
Lut block

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