Repository logo
 

Obliquity‐driven mountain permafrost‐related fluvial magnetic susceptibility cycles in the Quaternary mid‐latitude long‐term (2.5 Ma) fluvial Maros Fan in the Pannonian Basin

Published version

Published version
Peer-reviewed

Repository DOI


Loading...
Thumbnail Image

Type

Article

Change log

Authors

Gibbard, Philip L 
Kiss, László Ferenc 
McIntosh, Richard W 
Thamó‐Bozsó, Edit 

Abstract

jats:pMagnetic susceptibility (MS) of the Quaternary long‐term mid‐latitude Maros fluvial fan (Pannonian Basin) was recorded to understand the stratigraphical features of source‐proximal fluvial depositional settings. Three fully cored 500‐m‐deep boreholes were sampled at 0.5‐m intervals; low‐field and frequency dependent MS were measured, and complementary hysteresis and SEM‐EDAX investigations were performed on selected samples. Logged susceptibility data were also used to log correlations established by a simultaneous comparison of wireline log and laboratory measurements. Time‐series analyses of the susceptibility records reveal a ~41‐ka and ~100‐ka cyclicity. Towards the source‐distal sections the intensity of the ~41‐ka cycles decreases, while that of the ~100‐ka cycles remains strong. Stratigraphical and spectral similarities were observed between the Maros fluvial fan and Chinese loess records; however, based on complementary magnetic data, the magnetic phase of the Maros Fan sections is related to the detrital magnetite that originates from the catchment during early postglacial permafrost degradations. The amplification of the ~41‐ka cycles can be attributed to the very high susceptibility values in source‐proximal settings and to the special stratigraphical feature of the distributive fluvial systems. This comprises the increased avulsion frequency on the fluvial fans in ‘glacial recession periods’, in concert with the ‘early postglacial’ occurrence of the permafrost‐related magnetite originating from the catchment. As a local phenomenon, this is significant since it records the obliquity‐driven variations in permafrost development in a catchment. However, fluvial and alluvial fans are widespread depositional landforms within the Eurasian mountain range and were possibly the same during the Quaternary deglaciations. Thus, obliquity‐driven magnetic susceptibility variations in source‐proximal fan deposits attached or adjacent to regions of loess deposition should also be considered when scanning for potential source material of aeolian deposits.</jats:p>

Description

Keywords

Journal Title

Boreas

Conference Name

Journal ISSN

0300-9483
1502-3885

Volume Title

Publisher

Wiley