کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4464484 1621733 2006 14 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Contrasting conditions preceding MIS3 and MIS2 Heinrich events
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
Contrasting conditions preceding MIS3 and MIS2 Heinrich events
چکیده انگلیسی

This paper presents an integrated multi-tracer study performed on piston cores recovered in the glacial ice-rafted detritus belt, stretching from Newfoundland to the Irish margin across the North Atlantic (40–55°N), in order to compare in detail the internal structure of each Heinrich event (HE). These tracers are IRD counts (quartz, dolomite, volcanic grains), their Nd isotopic composition and Ar–Ar datings of individual hornblende grains. A focus on the detailed structure of HE confirms that all intervals of massive sediment flux, specifically Heinrich layers HL1-to-5 (HLs), were dominated by North American, Laurentide ice-sheet surges from Hudson Strait, that are evident as far east as the Bay of Biscay (European margin). The sequences of events leading up to the HLs, however, present significant dissimilarities. One important difference is that HL2 and HL1 were preceded by “precursor events” (increases in the number of lithic grains per gram from non-Laurentide sediment sources). Sediment debris derived from near-simultaneous iceberg releases originating from the European ice-sheet are only detectable close to the European margin. In contrast there are no comparable precursor events before HL5 and HL4. This observation implies that precursor events are unlikely to be mechanistically linked to the triggering of HEs. The similarity of the HLs, against contrasting background conditions, is a significant observation that should add constraints to their origin.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Global and Planetary Change - Volume 54, Issues 3–4, December 2006, Pages 225–238
نویسندگان
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