کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4689200 1636037 2015 19 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Sedimentary record of a fluctuating ice margin from the Pennsylvanian of western Gondwana: Paraná Basin, southern Brazil
ترجمه فارسی عنوان
رکورد رسوب یک حاشیه ی یخ از پنسیلوانیا غربی غربی: پارانا! حوضه جنوبی برزیل
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
چکیده انگلیسی


• Bashkirian/Moscovian glacial deposits from eastern Paraná Basin record subglacial to glaciomarine sedimentation.
• The stratigraphic architecture of the glacial deposits indicates deposition in an unconfined glacial setting.
• Multiple glacial lobes reached eastern Paraná Basin flowing from an ice cap on highlands of western Namibia.

The Paraná Basin is a key locality in the context of the Late Paleozoic Ice Age (LPIA) because of its location east of the Andean proto-margin of Gondwana and west of contiguous interior basins today found in western Africa. In this paper we document the sedimentary record associated with an ice margin that reached the eastern border of the Paraná Basin during the Pennsylvanian, with the aim of interpreting the depositional environments and discussing paleogeographic implications. The examined stratigraphic succession is divided in four stacked facies associations that record an upward transition from subglacial to glaciomarine environments. Deposition took place during deglaciation but was punctuated by minor readvances of the ice margin that deformed the sediment pile. Tillites, well-preserved landforms of subglacial erosion and glaciotectonic deformational structures indicate that the ice flowed to the north and northwest and that the ice margin did not advance far throughout the basin during the glacial maximum. Consequently, time-equivalent glacial deposits that crop out in other localities of eastern Paraná Basin are better explained by assuming multiple smaller ice lobes instead of one single large glacier. These ice lobes flowed from an ice cap covering uplifted lands now located in western Namibia, where glacial deposits are younger and occur confined within paleovalleys cut onto the Precambrian basement. This conclusion corroborates the idea of a topographically-controlled ice-spreading center in southwestern Africa and does not support the view of a large polar ice sheet controlling deposition in the Paraná Basin during the LPIA.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Sedimentary Geology - Volume 326, 1 August 2015, Pages 45–63
نویسندگان
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