Abstract
A three‐dimensional gravity modeling combined with integrated heat flow and elevation modeling is conducted to map out the crustal and lithospheric mantle thickness in the Alboran Basin, in the westernmost Mediterranean. A “sediment”‐corrected Bouguer anomaly has been derived using a depth‐to‐the‐basement map and densities determined from well logs and seismic data. The gravity effect of the base of the lithosphere has been removed from the sediment‐corrected Bouguer anomaly to obtain a “crustal” Bouguer anomaly, which has been inverted for crustal thickness. The resulting lithospheric structure is further constrained by elevation data under the assumption of local isostasy. The low residual elevation anomalies obtained (±100 m in average) suggest that the area is in local isostasy, particularly the medium‐ and long‐wavelength topography features. Variations in crustal thickness range from 36 km underneath the Betic and Rif Chains to <12 km beneath the easternmost part of the Alboran Sea Basin, in the transition to the South Balearic Basin. In western Alboran the Moho lies at a rather constant depth of ∼18 km, deepening sharply toward the Gibraltar Strait down to 30–32 km. The base of the lithosphere shallows from 140 km depth in the Gibraltar Strait to <45 km depth in the easternmost Alboran Sea. Lithospheric thinning penetrates to the southeastern side of the Iberian margin crosscutting topographic highs of the central and eastern Betic Chain. Our results favor mantle delamination produced by detachment and subsequent peeling away of the lithospheric mantle rather than convective removal of the lithospheric mantle either by orogenic collapse or detachment and sinking of a lithospheric slab.
Highlights
Furthermoret,he genesisof the AlboranBasinhas been an extremelycontroversialsubject, and there is no generalThe Neogene extensional basins of the western agreemenatboutthe originandpossiblecausesof extensionMediterraneanoriginatedby late orogenicextensionon the in this basin
Data,up to now little effort hasbeenmadeto modelthe deep The Alboran Basin lies within a Miocene arc-shapedthrust structureof the lithospherebeneaththe entire basinand the belt formed by the Betic and Rif Chains
As mentionedabove,the topography/bathymetorfy the region has a high-frequencycontent(see Figure 2) and therebyis very unlikely that the topographicrelief is fully compensatedO. n the other hand, the high heat flow values observedin the Alboran region favor a case of a weak lithospherewith low valuesof elasticthickness.A flexural analysiscarriedout by van der Beekand Cloetingh[1992] showsthat the elasticthicknessin southernSpainis
Summary
Furthermoret,he genesisof the AlboranBasinhas been an extremelycontroversialsubject, and there is no general. Data,up to now little effort hasbeenmadeto modelthe deep The Alboran Basin lies within a Miocene arc-shapedthrust structureof the lithospherebeneaththe entire basinand the belt formed by the Betic (southernSpain) and Rif (northern mode of transition to the oceanic South Balearic Basin and to Morocco) Chains. The internal complexesof both chains, thesurroundincghainsI.n thispaperwepresenat 3-D gravity, comprising mainly alpine metamorphicunits, have N-S heatflow,andelevationmodel,whichhasbeenusedto map continuityacrossthe Gibraltar Arc and below the Alboran out spatial variationsin crustal and mantle lithosphere Sea, formingthe basementof the basin.The whole systemis thicknesisn thestudyregion.In ourmodelingapproachh, eat boundedto the north and southby the Iberian and African flow dataare usedto constrainthe present-dalyithospheric continentalforelandsand to the eastand west by the oceanic thicknessw, hereasgravitydata(after removingthe gravity South Balearic Basin and the Atlantic Ocean, respectively effectsof sedimentaryfill and asthenosphereh)ave been (Figure, insetmap).
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