On Some Geometric Prism Asymmetries

Lenci, F.; Doglioni, Carlo

doi:10.1007/978-3-540-69426-7_2

Cited by 13 publications

(17 citation statements)

References 68 publications

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“…In contrast, east directed subduction zones, like Andes, or northeast directed, like Himalayas, exhibit opposite signatures such as high structural elevation, generally no backarc basin, deeply rooted thrust planes affecting the whole crust and the lithospheric mantle, wide outcrops of metamorphic rocks, and dominantly low angle dip of the slab (Bevis et al, 1995;Harabaglia and Doglioni, 1998;Doglioni et al, 2007Doglioni et al, , 2009Lenci and Doglioni, 2007). The E or NE directed slabs have also slower sinking velocity than the opposite W-directed subduction zones (Doglioni et al, 2009) (Fig.…”

Section: Tectonomagmatic Implicationsmentioning

confidence: 85%

Sr–Nd isotope geochemistry and petrogenesis of the Chah-Shaljami granitoids (Lut Block, Eastern Iran)

Arjmandzadeh

Karimpour

Mazaheri

et al. 2011

Journal of Asian Earth Sciences

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Section: Tectonomagmatic Implicationsmentioning

confidence: 85%

Sr–Nd isotope geochemistry and petrogenesis of the Chah-Shaljami granitoids (Lut Block, Eastern Iran)

Arjmandzadeh

Karimpour

Mazaheri

et al. 2011

Journal of Asian Earth Sciences

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“…For given convergence and subduction rates, the depth of the decollement in an accretionary prism determines the volume of the accreted rocks: The deeper the decollement, the largest the volume. Therefore, also, topography is controlled by the decollement depth (Bigi et al, 2003;Lenci et al, 2004;Lenci & Doglioni, 2007).…”

Section: Introductionmentioning

confidence: 99%

The Decollement Depth of Active Thrust Faults in Italy: Implications on Potential Earthquake Magnitude

2019

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Thrust fault ruptures during earthquakes do not often propagate down to the brittle‐ductile transition. Lithological variations control the behavior and depth of regional basal thrusts and decollement planes. Thrust fronts may be discontinuous along strike, limiting the dimension of single coseismic ruptures. These factors control the maximum expected magnitude in one region. This is the case of Italy where the convergence of few millimeter per year in the Apennines accretionary prism and along the retrobelt of the Alps generates compressional earthquakes with moderate to strong magnitudes. Here, using geological and geophysical data, we first compile a map of the undulated active basal thrust decollement for Italy that occurs from 1 to 17‐km depth. Then, we verify the relationship between the length of seismogenic ruptures in thrust faults (Lf) and the maximum depth of thrust faulting (zmax) of related earthquakes and find that their ratio (Lf/zmax) ranges between 2 and 4. Finally, we compute the potential seismogenic volume and estimate the maximum magnitude using an empirical relationship that multiplies the decollement depth and the Lf/zmax ratio. Maximum calculated magnitude is 6.7 ± 0.37 (depending on Lf/zmax and fault dip angle), consistent with the largest magnitude of thrust‐related earthquakes recorded in Italy (6.5–7.0). Lower magnitudes are predicted in the Ionian Seas at the external front of the Apennines where smaller crustal volumes are involved, whereas higher magnitudes are expected in the southern Po Basin, the western Adriatic Sea, Sicily offshore, and the Southern Alps where the decollement is deeper and the brittle volumes are far greater.

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“…Both the SE-dipping topographic slope of the wedge (about 1°) and the wedge taper (about 2-3°; Torelli et al, 2007;Polonia et al, 2008) are very low compared with other prisms worldwide (Clift and Vannucchi, 2004;Lenci and Doglioni, 2007). These values require low basal friction conditions or a weak de´colle´ment level (Davis et al, 1983;Dahlen et al, 1984), usually of salt.…”

Section: General Backgroundmentioning

confidence: 99%

“…However, the ECA is a unique accretionary wedge showing, unusually, both a low de´colle´ment dip and narrow taper (Lenci and Doglioni, 2007) and the highest outward growth rate of its deformation front (Torelli et al, 2007), perhaps reflecting the occurrence of Messinian salt within the wedge (e.g. Polonia et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…The External Calabrian Arc (hereinafter ECA) was formed by the convergence of the African and European regions and the subduction of the Ionian plate beneath the Calabrian plate, as is clearly defined by seismicity (Chiarabba et al, 2008), the temporal and spatial pattern of volcanic activity (De Astis et al, 2003) and seismic tomography (Wortel and Spakman, 2000): offscraped sediments from the subducting Ionian plate have piled up along thrust faults opposite the European region. However, the ECA is a unique accretionary wedge showing, unusually, both a low de´colle´ment dip and narrow taper (Lenci and Doglioni, 2007) and the highest outward growth rate of its deformation front (Torelli et al, 2007), perhaps reflecting the occurrence of Messinian salt within the wedge (e.g. Polonia et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Shallow structures at the outer Calabrian accretionary wedge (NW Ionian Sea): new insights from recently migrated reflection data

Valenti

2010

Terra Nova

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Terra Nova, 00, 000–000, 2010 Abstract Post‐stack time migration of a set of seismic reflection profiles reveals details of the stratigraphic–structural setting of the outermost Calabrian accretionary wedge, in the NW sector of the Ionian Sea, with particular emphasis on the Messinian stratigraphy and the deformation style of the thin frontal portion of this wedge. A structural style and seismic facies analysis, calibrated by refraction data, images a general bipartition of the Messinian evaporite deposits: the `lower subunit', consisting mainly of salt, appears to have undergone ductile‐flow deformation, and the `upper subunit', consisting mainly of gypsum and marls, appears to be characterized by brittle deformation. Lateral variations in evaporite composition and/or thickness reflect a change in the deformation style of the accretionary wedge, with the development of double‐verging imbricated thrust sheets of the whole Messinian sequence. Gravitational‐slide tectonics of the unstable accretionary wedge, too steep to support a skinny evaporite‐based top layer, characterize the outermost wedge, indicating here a near‐surface `olistostrome' from the Late Messinian.

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On Some Geometric Prism Asymmetries

Cited by 13 publications

References 68 publications

Sr–Nd isotope geochemistry and petrogenesis of the Chah-Shaljami granitoids (Lut Block, Eastern Iran)

Sr–Nd isotope geochemistry and petrogenesis of the Chah-Shaljami granitoids (Lut Block, Eastern Iran)

The Decollement Depth of Active Thrust Faults in Italy: Implications on Potential Earthquake Magnitude

Shallow structures at the outer Calabrian accretionary wedge (NW Ionian Sea): new insights from recently migrated reflection data

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