Ultrafast oceanic spreading of the Marsili Basin, southern Tyrrhenian Sea; evidence from magnetic anomaly analysis

Spectral analysis of both shipborne and airborne magnetic maps of the southern Tyrrhenian Sea reveals seven subparallel positive-negative magnetic anomaly stripes over the flat-lying deep floor of the Marsili oceanic basin. This represents the first evidence of oceanic magnetic anomalies in the Tyrr...

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Bibliographic Details
Published in:Geology (Boulder) 2006-09, Vol.34 (9), p.717-720
Main Authors: Nicolosi, Iacopo, Speranza, Fabio, Chiappini, Massimo
Format: Article
Language:English
Subjects:
airborne methods
algae
Analysis
Basins
biostratigraphy
Cenozoic
clastic sediments
Foraminifera
Geology
geophysical methods
geophysical surveys
Geophysics
Globigerinacea
Globorotalia
Globorotalia truncatulinoides
Globorotaliidae
Invertebrata
magnetic anomalies
magnetic methods
Marine
marine methods
marine sediments
Marsili Basin
Marsili Seamount
Mediterranean Sea
microfossils
nannofossils
Neogene
ocean floors
Oceans
ooze
periodicity
Plantae
Pleistocene
Pliocene
Protista
Quaternary
rates
Rotaliina
sea-floor spreading
seamounts
sediments
solid Earth (tectonophysics)
Stratigraphy
surveys
Tertiary
Tyrrhenian Sea
West Mediterranean
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Summary:Spectral analysis of both shipborne and airborne magnetic maps of the southern Tyrrhenian Sea reveals seven subparallel positive-negative magnetic anomaly stripes over the flat-lying deep floor of the Marsili oceanic basin. This represents the first evidence of oceanic magnetic anomalies in the Tyrrhenian Sea. The central positive stripe is along the Marsili seamount, a superinflated spreading ridge located at the basin axis. The stratigraphy of Ocean Drilling Program Site 650 and K/Ar ages from the Marsili seamount suggest that the Marsili Basin opened at the remarkable full-spreading rate of ∼19 cm/ yr between ca. 1.6 and 2.1 Ma about the Olduvai subchron. This is the highest spreading rate ever documented, including that observed at the Cocos-Pacific plate boundary. Renewed but slow spreading during the Brunhes chron (after 0.78 Ma), coupled with huge magmatic inflation, gave rise to the Marsili volcano. Our new data and interpretation show that backarc spreading of the Tyrrhenian Sea was episodic, with sudden rapid pulses punctuating relatively long periods of tectonic quiescence.
ISSN:0091-7613
1943-2682
DOI:10.1130/G22555.1