Publication Date:
2017-04-04
Description:
We present results of detailed paleomagnetic investigations on deep!sea cores from
sediment drifts located along the Pacific continental margin of the Antarctic Peninsula.
High!resolution magnetic measurements on u channel samples provide detailed age
models for three cores collected from drift 7, which document an age of 122 ka for the
oldest sediments recovered near the drift crest at site SED!07 and a high sedimentation rate
(11 cm/kyr) at site SED!12 located close to the Alexander Channel system. Low! and
high!temperature magnetic measurements in conjunction with microscopic and
mineralogic observations from drifts 4, 5 and 7 indicate that pseudosingle!domain detrital
titanomagnetite (partially oxidized and with limited Ti substitution) is the dominant
magnetic mineral in the drift sediments. The titanomagnetite occurs in two magnetic
forms: (1) a low!coercivity form similar to laboratory!synthesized titanomagnetite
and (2) a high!coercivity form (Bcr 〉 60 mT). These two forms vary in amount and
stratigraphic distribution across the drifts. We did not find evidence for diagenetic
magnetic iron sulfides as has been previously suggested for these drift deposits. The
observed change of magnetic mineralogy in sediments deposited during Heinrich
events on drift 7 appears to be related to warming periods, which temporarily modified the
normal glacial transport pathways of glaciogenic detritus to and along the continental
rise and thus resulted in deposition of sediments with a different provenance.
Understanding this sediment provenance delivery signature at a wider spatial scale should
provide information about ice sheet dynamics in West Antarctica over the last !100 kyr.
Description:
Published
Description:
B06104
Description:
2.2. Laboratorio di paleomagnetismo
Description:
JCR Journal
Description:
partially_open
Keywords:
Antarctic Peninsula
;
Pacific margin
;
sediment drift
;
late Pleistocene
;
Mineral magnetism
;
relative palaeointensity
;
04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
;
04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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