کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4683942 1635380 2016 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Late Paleozoic paleofjord in the southernmost Parana Basin (Brazil): Geomorphology and sedimentary fill
ترجمه فارسی عنوان
پائول افجورد پائولوزوئیک در جنوب حوضه پارانا (برزیل): ژئومورفولوژی و پرکننده رسوبی
کلمات کلیدی
گاندوانا، عصر یخبندان پالئوزوئیک، پالو فورج، ژئومورفولوژی یخبندان
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
چکیده انگلیسی


• Analyzed the Mariana Pimentel paleovalley to know if it was a fjord during the late Paleozoic ice age.
• The paleovalley has typical features of modern glacial valleys.
• The sedimentary facies that fill the base of the paleovalley signs its glacial origin.

In the southernmost part of the Parana Basin, records of the late Paleozoic glaciation occur in a discontinuous form preserved in paleovalley systems excavated in the crystalline basement. This paper addresses one of these paleovalleys, the Mariana Pimentel, which extends over 60 km with NW-SE valley direction and a constant width of 2.5 km. With the objective of demonstrating that the paleovalley worked as a fjord during the glaciation period, its origin as well as sedimentary fill and morphology were analyzed. The paleovalley morphology was obtained through electrical resistivity (electrical sounding and lateral mapping) and mathematical modeling in four transverse sections. The morphology of the paleovalley documented by the U-shape, steady width, and high depth reaching up to 400 m are typical features of modern glacial valleys. The sedimentary facies that fill the base of the paleovalley, such as rhythmites and dropstones with thickness up to 70 m and diamictites with faceted pebbles (up to 5 m thick) are signs of its glacial origin. During the glaciation period, the paleovalley had a connection to the epicontinental sea located to the northwest, extended toward Namibia, and was excavated by glaciers from the highlands of this region. Thus, the evidence attests that the Mariana Pimentel paleovalley was a fjord during the late Paleozoic glaciation. The duration of the late Paleozoic glaciation (which is longer than the Quaternary glaciation), the apatite fission track that suggests erosion up to 4 km thick in the study area, and the lack of preserved hanging valleys in the Mariana Pimentel indicate that the paleovalley once featured a higher dimension. Furthermore, the existence of paleofjords excavated in the border of the basement corroborates the idea of small ice centers controlled by topography during the late Paleozoic glaciation.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geomorphology - Volume 269, 15 September 2016, Pages 203–214
نویسندگان
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