نشریه علوم زمین خوارزمی

نشریه علوم زمین خوارزمی

ژئوشیمی تودۀ ساب ولکانیک تلخ‌رود، آتشفشان دماوند

نویسندگان
دانشگاه خوارزمی، دانشکدۀ علوم زمین
چکیده
محدوده‌ای در امتداد درۀ تلخ‌رود در دامنۀ شمال‌شرق آتشفشان دماوند توده­ای ساب ولکانیک شامل سینودیوریت، مونزونیت و کوارتز مونزونیت رخنمون دارد. این توده ساب ولکانیک با بافت پورفیری دارای فلدسپارهای پلاژیوکلاز و قلیایی، فلوگوپیت، آمفیبول، کلینوپیروکسن، آپاتیت و تیتانومگنتیت است. شواهد نامتعادل نظیر زونینگ و بافت غربالی در پلاژیوکلاز و اپاسیتی شدن بلورهای فلوگوپیت می­تواند ناشی از تغییرات فشار بخار آب در حین صعود ماگما باشد. این توده از نظر خصوصیات ژئوشیمیایی، متا‌آلومین، آلکالن و شوشونیتی است و به لحاظ جای‌گاه تکتونیکی در محیط آتشفشان­های درون‌صفحه­ای قرار می­گیرد. نمودارهای چند عنصری نرمالیز شده با کندریت و گوشتۀ اولیه غنی‌شدگی عناصر LREE و LILE و تهی‌شدگی HREE و HFSE مانند Ti, Nb را نشان می‌دهند. مقایسۀ این سنگ­ها با معادل­های خروجی آن­ها یعنی تراکی آندزیت‌ها و تراکیت‌های دماوند نشان می‌دهد که تفاوت ژئوشیمی و کانی‌شناسی محسوسی بین آنها وجود ندارد.


کلیدواژه‌ها

عنوان مقاله English

Geochemistry of Talkh-rud Sub-volcanic Intrusion, Damavand Volcano

نویسندگان English

roya aliakbari
amir ali Tabbakh Shabani
Shahryar Mahmoudi
Kharzmi University
چکیده English

The study subvolcanic intrusion, comprising syenodiorite, monzonite and quartz-monzonite, is cropped out in Talkh-rud valley located in the northeast of Damavand volcano flank. This sub-volcanic intrusion possesses porphyritic texture and consists of plagioclase, alkali feldspar, phelogopite, amphibole, clinopyroxene, apatite and titanomagnetite. Evidences of disequilibrium such as zoning and sieve textures in plagioclase and opacity of phlogopite crystals could be due to variations in water vapor pressure during magma ascent. The intrusion is geochemically metaluminous, alkaline and shoshonitic and tectonically plots in the realm of within plate volcanics. Normalized to the chondrite and primary mantle multi elemental spider diagrams show enrichment of LREE and LILE and depletion of HREE and HFSE such as Ti, Nb. Comparison of these rocks with their extrusive counterparts, i.e., trachy-andesites and trachytes of Damavand shows no significant difference between the geochemistry and mineralogy.

کلیدواژه‌ها English

Damavand volcano
Sub-volcanic
Talkh-rud
Alkaline
Shoshonitic
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