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ODP leg 107 in the Tyrrhenian Sea; insights into passive margin and back-arc basin evolution

Kim Kastens, Jean Mascle, Christian A. Auroux, Enrico Bonatti, Cristina Broglia, James Channell, Pietro Curzi, Kay-Christian Emeis, Georgette Glacon, Shiro Hasegawa, Werner Hieke, Georges Mascle, Floyd McCoy, Judith McKenzie, James Mendelson, Carla Mueller, Jean-Pierre Rehault, Alastair Robertson, Renzo Sartori, Rodolfo Sprovieri and Masayuki Torii
ODP leg 107 in the Tyrrhenian Sea; insights into passive margin and back-arc basin evolution
Geological Society of America Bulletin (July 1988) 100 (7): 1140-1156

Abstract

Leg 107 of the Ocean Drilling Program drilled a west-northwest-east-southeast transect of seven sites across the Tyrrhenian Sea, the youngest of the sub-basins of the Mediterranean Sea. Sites 654, 653, 652, and 656 document the rifting and subsidence of the Sardinia passive continental margin. On the upper margin (Site 654), we cored a classic transgressive sequence: subaerial conglomerates, overlain by oyster-bearing sands, overlain by marine marl. Comparison between the recovered lithologies and seismic reflection profiles suggests that the synrift sediments on the upper margin are Tortonian (late Miocene) to Messinian (latest Miocene) in age, whereas synrift sediments on the lower margin are Messinian to Pliocene in age. During the Messinian desiccation of the Mediterranean, Sites 654 and 653, now on the upper Sardinian margin, apparently occupied a basinal setting, where they received nannoplankton-bearing clays interbedded with laminated gypsum. Sites 656 and 652, now on the lower Sardinia margin, were apparently higher standing during the desiccation event; their Messinian facies are subaerial and lacustrine, respectively. We infer from these lines of evidence that tilting and subsidence occurred more than a million years earlier on the upper margin than on the lower margin. Such diachroneity can be interpreted in terms of migration of the zone of maximum extension above a "rolling-back" subduction zone, or in terms of extension of continental crust, by shear along a deep "detachment fault."Sites 655, 651, and 650 were drilled into two small basalt-floored basins of the central and eastern Tyrrhenian. Emplacement of basaltic crust in the central Tyrrhenian (Vavilov Basin) apparently began more than a million years before, emplacement of basaltic crust in the eastern Tyrrhenian (Marsili Basin). This observation is compatible with previous suggestions that the Tyrrhenian has grown southeastward in response to "rollback" of the down-going slab that currently dips northwestward under the toe of Italy. At the easternmost site, high vesicularity of the basalt and benthic foram assemblages in the oldest sediments imply that the basalt erupted in water shallower than 2,500 m. It has apparently subsequently subsided to its present depth of >4,100 m below sea level nearly three times as fast as normal subsidence of crust formed at a mid-ocean ridge.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 100
Serial Issue: 7
Title: ODP leg 107 in the Tyrrhenian Sea; insights into passive margin and back-arc basin evolution
Affiliation: Lamont-Doherty Geol. Obs., Palisades, NY, United States
Pages: 1140-1156
Published: 198807
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 83
Accession Number: 1988-046785
Categories: Solid-earth geophysicsOceanography
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Lamont-Doherty Geol. Obs., Contrib.
Illustration Description: illus. incl. sects., sketch maps
N39°00'00" - N41°00'00", E10°30'00" - E14°00'00"
Secondary Affiliation: Univ. Pierre et Marie Curie, FRA, FranceTex. A&M Univ., USA, United StatesUniv. Fla., USA, United StatesIst. Geol. Mar., ITA, ItalyUniv. Provence, FRA, FranceTohoku Univ., JPN, JapanTech. Univ. Muenchen, DEU, Federal Republic of GermanyInst. Dolomieu, FRA, FranceMass. Inst. Technol., USA, United StatesUniv. Frankfurt, DEU, Federal Republic of GermanyUniv. Edinburgh, GBR, United KingdomIst. Geol., ITA, ItalyKyoto Univ., JPN, Japan
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1988
Program Name: DSDPDeep Sea Drilling Project
Program Name: ODPOcean Drilling Program
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