The Alpine Tethys rifted margins: Reconciling old and new ideas to understand the stratigraphic architecture of magma-poor rifted margins

Emmanuel Masini; Gianreto Manatschal; Geoffroy Mohn

doi:10.1111/sed.12017

The Alpine Tethys rifted margins: Reconciling old and new ideas to understand the stratigraphic architecture of magma-poor rifted margins

Sedimentology ◽

10.1111/sed.12017 ◽

2013 ◽

Vol 60 (1) ◽

pp. 174-196 ◽

Cited By ~ 65

Author(s):

Emmanuel Masini ◽

Gianreto Manatschal ◽

Geoffroy Mohn

Keyword(s):

Rifted Margins ◽

Stratigraphic Architecture ◽

New Ideas

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The architecture and the multi-stage evolution of the North Iberian margin (Bay of Biscay)

10.5194/egusphere-egu2020-3964 ◽

2020 ◽

Author(s):

Patricia Cadenas ◽

Gianreto Manatschal ◽

Gabriela Fernández-Viejo

Keyword(s):

Rift System ◽

Plate Boundaries ◽

Bay Of Biscay ◽

Velocity Models ◽

The North ◽

Rifted Margins ◽

Multi Stage ◽

Stratigraphic Architecture ◽

Half Graben ◽

Iberian Margin

In this work, we address the problem of the formation and reactivation of multi-stage rifting based on the study of the central North Iberian margin, located at the southern Bay of Biscay triangular oceanic domain. This magma-poor rifted margin registered three major Mesozoic rift events and a subsequent Alpine compressional reactivation, representing a unique setting to study the architecture of a multi-stage rift system and its control on subsequent reactivation. Based on a dense dataset of high quality 2D seismic reflection profiles, boreholes and published velocity models, we define, describe and map structural domains, major extensional and compressional structures, and the depth and thickness of syn-rift units. We provide new structural maps showing the geometry and spatial distribution of major rift basins and bounding structures.The analysis of the tectono-stratigraphic architecture led us to define three rift systems. A diffuse and widespread of Triassic age, with classical fault-bounded half-graben basins, a second, narrow, deep and localised Late Jurassic to Barremian transtensional system, and a third, widely distributed Aptian to Cenomanian hyperextended system, including two distinctive domains. Our results show that each rift system controlled successive rift events, and that the stacking and overlap of the three rift systems resulted in a complex and segmented 3D template that guided subsequent compressional reactivation. Compression affected on a distinctive way the three rift systems, leading to an amplification of the margin segmentation.This work shows that unravelling the tectono-stratigraphic architecture and evolution of multi-stage rift systems can provide key insights not only to decipher the spatial and temporal evolution of divergent plate boundaries, but also to set up present-day kinematic templates to test dynamic plate deformable models of conjugate rifted margins. It will also be a keystone to constrain early stages of margin reactivation and the architecture of reactivated rifted margins now incorporated in orogenic systems.

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Basement-decoupled hyperextension rifting: The tectono-stratigraphic record of the salt-rich Pyrenean necking zone (Arzacq Basin, SW France)

Geological Society of America Bulletin ◽

10.1130/b35974.1 ◽

2021 ◽

Author(s):

M. Ducoux ◽

E. Masini ◽

J. Tugend ◽

J. Gómez-Romeu ◽

S. Calassou

Keyword(s):

Rift System ◽

Rifted Margins ◽

Salt Layer ◽

Stratigraphic Architecture ◽

Stratigraphic Record ◽

Half Graben ◽

Southern Side ◽

Well Data ◽

Stratigraphic Evolution ◽

Sw France

Half grabens and supra-detachment basins correspond to end-member basin types of magma-poor rift settings, each of them showing a characteristic stratigraphic architecture. The occurrence of a basement-cover décollement has been shown to drastically change the stratigraphic architecture of half graben basins, however, the effect of such basement-cover décollement remains to be documented in supra-detachment basins formed during hyper-extension. We investigate the tectono-stratigraphic record of the Arzacq Basin (SW France) recording the formation of a salt-rich Cretaceous hyperextended rift system. Combining 2-D and 3-D seismic reflection calibrated from well data, we show that this basin is an asymmetric syn-rift extensional syncline growing above a pre-kinematic salt layer. By mapping the sub-salt basement, we show that the formation of this syncline is controlled by the South-Arzacq Fault (SAF), soling in the sub-salt basement. Based on crosscutting relationships and the observed southward migration of syn-rift depocenters, this N110°-striking, 20°-dipping structure accommodates >10 km of thick-skinned extension. The overlying supra-salt cover coherently glided, following the basement geometry. The 3-D segmentation of the SAF and the sub-salt stratigraphic architecture of the Arzacq Basin suggest a roughly dip-slip kinematic. A post-kinematic kilometer-scale uplift is documented on the southern side of the Arzacq Basin. It may result from the increasing lithospheric thinning and thermal support at the end of asymmetric hyperextension. As salt commonly occurs in extensional settings, we believe that our description of the tectono-stratigraphic record of a basement-decoupled supra-detachment basin has global applicability to unleash the tectono-stratigraphic evolution of worldwide hyper-extended rifted margins.

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