کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4741471 1641514 2014 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Paleomagnetic study of juvenile basaltic–andesite clasts from Andean pyroclastic density current deposits
ترجمه فارسی عنوان
مطالعات پالموژنتیک از کانسرهای آندزیتی بازالتیک نوجوانان از رسوبات فعلی تراکم پری کلاسیک آند
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فیزیک زمین (ژئو فیزیک)
چکیده انگلیسی


• We present new paleomagnetic results from juvenile clasts of three PDC deposits of andesitic–basaltic composition.
• Juvenile clasts record a TRM with a reliable record of the Earth’s magnetic field.
• The magnetic carriers are mainly single domain Ti-rich titanomagnetite.
• This material permits high-quality paleointensity determinations.

Additional paleomagnetic data are necessary to improve geomagnetic models of secular variation during the Holocene, especially from the southern hemisphere. In most of the Andean volcanoes from Ecuador to the Chilean central volcanic zone, very well dated lava flows are rare. In contrast, andesitic to basaltic pyroclastic density current (PDC) deposits commonly contain charcoal, facilitating their age determination with 14C. In this study we present the magnetic properties and the paleomagnetic results obtained from three PDC deposits of basaltic to andesitic composition. One is the 2006 PDC deposit from the Ecuadorian Tungurahua volcano and the two others are well-dated PDC deposits from Chilean volcanoes Osorno and Villarica. Although most paleomagnetic studies in pyroclastic rocks deal with the estimation of emplacement temperatures from bulk deposits or accessory and accidental (non-juvenile) clasts, we show that juvenile clasts embedded in PDC deposits provide well-grouped paleomagnetic directions indicating post-emplacement in situ cooling below Curie points. Moreover, the rapid cooling of the juvenile clasts yields an abundance of single domain titanomagnetite grains providing low unblocking temperatures and a reliable material for paleointensity determination.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physics of the Earth and Planetary Interiors - Volume 227, February 2014, Pages 20–29
نویسندگان
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