The carriers of AMS in remagnetized carbonates. Insights for remagnetization mechanism and basin evolution

Inversion tectonics and magnetic fabrics in Mesozoic basins of the Western Tethys: A review

“…These overlappings and the structural observations reveal the primary origin of the RT-AMS. In other cases, when ferromagnetic fabrics are analyzed and they do not overlap RT-AMS/LT-AMS carried by phyllosilicates, they indicate the different timing and strain ellipsoid orientation for the ferromagnetic fabric development respect to the RT-AMS/LT-AMS fabric (Calvín et al, 2018a). This fact is also well known from previous studies from the literature, that do not necessarily relate to inversion of extensional basins.…”

“…Besides, the coincidence between the AARM and the RT-AMS in most of the limestones sampled in the Central High Atlas suggests a major contribution of magnetite to the bulk magnetic fabric (Calvín et al, 2018a). In this case, the long axis of the magnetic anisotropy ellipsoid has been interpreted to show the extensional direction during authigenic magnetite growth also during basin evolution (Calvín et al, 2018b).…”

“…In general, the relationship between the orientation of these ferromagnetic subfabrics and the main RT-AMS orientation is easily established in each case (e.g. Soto et al, 2007bSoto et al, , 2008aGarcía-Lasanta et al, 2014;Calvín et al, 2018aCalvín et al, , 2018b. These ferromagnetic minerals reveal themselves when applying remanencerelated analyses (IRM and backfield curves, Fig.…”

“…The evolution of extensional or transtensional basins can include one or several stages of rifting (Salas and Casas, 1993), characterized by tectonic or thermal subsidence, depending on the processes dominant during the basinal stage, or upon interference with plate or mantle-related processes (Torres-López et al, 2014). The latter can also influence the magnetic properties of rocks (Osete et al, 2011) and hence the magnetic fabrics (Calvín et al, 2018a). As we will discuss later on, AMS can offer a reliable picture of early or intermediate stages of basin evolution, depending on the particular features of the tectonic inversion on each basin that can eventually modify previous, basin-related magnetic fabrics.…”

“…In the studied basins, an interesting application of magnetite-driven fabrics in sedimentary rocks is the contribution of SP magnetite to the AMS, a feature in which remagnetization had a strong influence (Calvín et al, 2018a). In some of the studied basins (Cabuérniga, Cameros, Central High Atlas, Soto et al, 2007b;García-Lasanta et al, 2014, Calvín et al, 2018a, the fabric carried by magnetite indicates the extension direction linked to the basinal stage, and specifically in the Central High Atlas (Imilchil Area), it indicates the stretching at the remagnetization time (Calvín et al, 2018a).…”