Correlation of Seafloor Spreading Magnetic Anomalies across King's Trough, Northeast Atlantic Ocean

Abstract

Taking into account the DSDP Leg 94 site survey and drilling results, a review of the magnetic data from the flanks of King's Trough has led to analysis of 12 tracks running subparallel to the feature. Magnetic anomalies have been projected as profiles on an azimuth of 110°, coincident with the regional trend of magnetic lineations. Comparison of the profiles with a reversal chronology model has shown unambiguous anomaly identifications to the north which extend close to the Trough on its north flank. South of the Trough the anomaly sequence is less clear.Anomaly identifications across King's Trough have previously been used as evidence of dextral offset. This chapter, however, follows recent studies suggesting that a dextral offset of up to 45 km exists on a fracture zone just to the south, and implying that the Trough itself shows no offset along its axis.Studies reported here have expanded that interpretation to incorporate the dating control of Leg 94 Site 608 into the model. The results define the position of a transform, probably in existence during the period between Anomalies 31 and 18, encompassing the early part of the Pyrenean convergence. In addition, other discontinuities are shown to have existed in the magnetic lineations north and south of King's Trough during the same interval. These predate the later Miocene tectonic events responsible for subsidence of the crust that makes up the King's Trough basins, after its formation from a hot spot.

A New Southern North Atlantic Isochron Map: Insights Into the Drift of the Iberian Plate Since the Late Cretaceous

“…Iberia has been studied extensively since the 1980s through models describing the southern North Atlantic kinematics. These models were based on the analysis of marine magnetic anomalies and bathymetric or gravity data (DeMets et al, ; Kerr et al, ; Klitgord & Schouten, ; Merkouriev & DeMets, , , ; Miles & Kidd, ; Müller & Roest, ; Müller et al, , , ; Olivet et al, ; Olivet, ; Roest & Srivastava, ; Srivastava & Tapscott, ; Srivastava & Roest, , , ; Srivastava, Roest, et al, ; Srivastava, Schouten, et al, ; Srivastava et al, ; Sibuet & Collette, ; Sibuet, Srivastava, & Spakman, ; Sibuet, Monti, et al, ; Torsvik et al, ; Verhoef et al, ; Vogt, ) or on the reinterpretation of previously published data sets (e.g., rotation poles) to remove inconsistencies in the kinematic reconstructions (Rosenbaum, Lister, & Duboz, ; Vissers & Meijer, , ). The seafloor spreading history of the southern North Atlantic between Iberia and Newfoundland and its relationship to the formation of the Pyrenees and Betic‐Rif system (Figure ) has been described involving successive jumps of the plate boundary between Iberia, Europe, and Africa from north (Bay of Biscay axis, B and King's Trough, KT; Figure ) to south (Azores Gibraltar Fracture Zone, AGFZ; Figure ) (Klitgord & Schouten, ; Olivet, ; Roest & Srivastava, ; Rosenbaum et al, ; Sibuet, Srivastava, & Spakman, ; Srivastava, Roest, et al, ; Srivastava, Schouten, et al, ; Vissers & Meijer, , ).…”

King's Trough: reactivated pseudo-fault of a propagating rift

“…The extensive magnetic data that exist in the eastern North Atlantic have been compiled in the form of maps showing the presence of lineated magnetic anomalies (Roberts, Jones & Hunter 1985;Verhoef et al 1986). These and other compilations (Miles & Kidd 1986 1986) show disruption in some of the anomalies across King's Trough. To examine this in more detail and to document the propagating model, Fig.…”

“…Furthermore, the bathy; metry does not show the presence of a major E-W fracture zone. Miles & Kidd (1986), on the other hand, indicated the existence of three fracture zones oriented parallel to King's Trough. Such an interpretation is, in our opinion, not right as these fracture zones do not conform with the overall direction of relative plate motion.…”