Mapping the Moho beneath the Southern Urals with wide‐angle reflections

Modelling and imaging the Moho transition: the case of the southern Urals

“…Therefore, it is necessary to investigate the influence of these shallow structures on the waveform of deep seismic reflections. The crustal thickness and the velocity depth function along the profile were estimated from the wide-angle shot gathers (Carbonell et al 1996(Carbonell et al , 1998. In particular we use the wide-angle seismic data from the URSEIS'95 multiseismic experiment (Berzin et al 1996;Carbonell et al 1996;Echtler et al 1996;Knapp et al 1996) because the Moho is well imaged by P and S waves in all the shot gathers.…”

Role of a phase: Change Moho in stabilization and preservation of the Southern Uralide orogen, Russia

“…Included in our study are (1) published near-vertical incidence/wide angle URSEIS seismic profile, (2) crustal-scale balanced cross-sections (3) published gravity, (4) topography, (5) published fission track data, and (6) published thermal modeling. Recent reprocessing of the URSEIS wide angle data [Carbonell et aL, 1998[Carbonell et aL, , 2000 suggested that the seismically defined Moho, corresponding to an increase in the P-wave velocity from -7.2 km/s to more than 8.0 km/s, occurs along a subhorizontal boundary at -53 km depth across the central portion of the orogen (50-300 km in Figures 2a and b). This boundary, picked on the basis of first arrivals of PmP waves on stacked versions ofthe wide-angle data, corresponds well with the downward disappearance of the well-defined Moho reflection on the eastern and western ends of the near vertical incidence URSEIS profile (-50 and 300 km in Figure 2a).…”

“…The fairly flat Moho at ~53 km depth from the URSEIS wide-angle data (Figure 2b) overprints the U ralian orogenic fabric [Carbonell et al, 1998], and consequently it must be younger than Uralian. The zircon and apatite fission-track data [Seward et al, 1997] indicate that the cooling ages for rocks exposed now at the surface cluster in the Late Triassic to Early Jurassic time (200-260 Ma), indicating that no significant erosion or uplift have occurred in the Southern Uralides since that time.…”

“…While the subhorizontal Moho on both sides of the orogen deepens gently toward the central part of the orogen, it loses the pronounced reflective character and cannot be clearly identified on the seismic reflection profile. Previous interpretations of this relationship involved projection of the Moho bound ary to depths of -60 km Carbonell et al, 1996Carbonell et al, , 1998]. More recent analysis of the velocity structure of the crustal root suggests it is characterized by high P-wave velocity (7.7-8.0 km/s) [Druzhinin et al, 1988;Thouvenotet al, 1995;Carbonell et aI., 1998Carbonell et aI., ,2000, and it was interpreted as either remnant of the Paleozoic collision [Kruise and McNutt, 1988] or interlayered sequences of eclogites and peridotites [Carbonell et al, 2000].…”

Models of the Earth’s crust from controlled-source seismology — Where we stand and where we go?

“…As demonstrated, e.g., by Malinowski (2009), reflectivity images formed based on wide-angle reflections complement velocity models and provide much more information for the geological interpretation. Attempts have been made to produce stacks of the WARR data (Carbonell et al 1998, Malinowski 2009, Mereu 2000 and apply pre-stack depth migration (e.g., Holbrook et al 1992, Milkereit et al 1990, Pilipenko et al 1999. Such an approach is hampered by the relatively large receiver/shot intervals Fig.…”