کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6347821 1313464 2016 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Influence of relative sea-level variations on the genesis of palaeoplacers, the examples of Sarrabus (Sardinia, Italy) and the Armorican Massif (western France)
ترجمه فارسی عنوان
تأثیر تغییرات نسبی سطح نسبی در پیدایش پهلوهای پلها، نمونه هایی از سارابوس (ساردینیا، ایتالیا) و ماسیف اوموریکا (غرب فرانسه)
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
چکیده انگلیسی
The aim of this work is to analyse the role of allocyclic processes in the genesis of marine Ordovician palaeoplacers laid down on a terrigenous shelf dominated by storm waves. Sedimentological (facies, sequence stratigraphy) and petrographic analyses combined with natural radioactivity measurement (gamma ray) are carried out. Two facies containing heavy minerals are identified: a shoreface facies and a proximal upper offshore facies. Heavy minerals (mainly titaniferous minerals, zircon and monazite) are concentrated in laminae that can amalgamate to form placers that are several decimetres thick. Their occurrence is highlighted by an increase in the total radioactivity (up to 140,000 cpm) and in the U and Th contents (up to 130 ppm and 800 ppm, respectively). The palaeoplacers are the result of a combination of autocyclic and allocyclic factors. In the stratigraphic record, the palaeoplacers are located in the retrogradation phases and express condensation processes in the nearshore environments.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Comptes Rendus Geoscience - Volume 348, Issue 2, February–March 2016, Pages 150-157
نویسندگان
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