Seismic Stratigraphic Framework of the Lima and Yaquina Forearc Basins, Peru

Abstract

The stratigraphic framework of the Lima and Yaquina forearc basins offshore Peru, determined from multichannel seismic (MCS) data, reveals significantly different Neogene histories in the two basins. Miocene deposition in the Lima Basin was controlled mainly by variations in the relative subsidence rates. Depositional processes, particularly contour currents, may have had a major influence during the Pliocene-Pleistocene. In contrast, the Yaquina Basin shows no evidence of assumed contourites. Severe disruption of the reflectors indicates active tectonism throughout the Neogene in the Yaquina Basin, while reflectors representing late Miocene and younger strata in the Lima Basin are largely undeformed, which indicates relative quiescence. Most sequences in the Lima Basin demonstrate the presence of a hinge line that separates the relatively thin, wedgeshaped landward part from a much thicker, lens-shaped seaward part. Generally, this hinge appears to represent a paleoslope break. Such hinge lines are not evident in the Yaquina Basin. Both basins exhibit migration of the depocenters of the various sequences through time. The movement is to the south and landward in the Lima Basin, while migration is northward in the Yaquina Basin. These migrations appear to be the result of variations in the relative subsidence rates within the basins. In the Lima Basin these movements are closely related to structural features in the basement. In addition to a structural trend that is oriented parallel to the margin, we observed a secondary structural trend that is oriented east-west. Development of structural features along this trend led to the development of two distinct depocenters in most of the stratigraphic sequences in the Lima Basin.

Seismic velocities from the Yaquina forearc basin off Peru: evidence for free gas within the gas hydrate stability zone

“…1), was the object of seismic pre-site surveys for ODP Leg 112 by the Hawaii Institute of Geophysics . The seismic stratigraphic framework was analysed by Ballesteros et al (1988) who found five sequences from middle Eocene (Y1) to late PlioceneQuarternary (Y5) with a total thickness of well over 1,000 m next to our study area. Bourgois et al (1988) presented a depth migrated reflection profile (CDP-2, see Fig.…”

“…Chemoherms, which evolved on the seafloor above gas hydrate charged sediments in the Lima Basin off Peru, may indicate that methane is able to migrate through the GHSZ (Pecher et al 2001). Hu¨bscher and Kukowski (2003) discussed an intricate and laterally varying reflection pattern from the BGHSZ in the Yaquina Basin north of the working area of ODP Leg 112 (Ballesteros et al 1988) (Fig. 1) along seismic line HH42.…”

“…The thin lines show the seismic profiles of the GEOPECO survey 2000, the bold lines are the seismic profiles discussed in this paper. The rectangle refers to the study area of Ballesteros et al (1988). ODP sites 683 and 684 are shown as well as the seismic profile CDP-2, which is represented by the dashed line.…”

Carbonate Cementation of Granular and Fracture Porosity: Implications for the Cenozoic Hydrologic Development of the Peru Continental Margin

“…The Cenozoic basins of the Peru continental margin are delimited by horstlike basement elements trending subparallel to the Andean structural grain (Travis et al, 1976;Thornburg and Kulm, 1981;Ballesteros et al, 1988) (Figs. 1, 2).…”

“…1,2; Hussong et al, 1988;Ballesteros et al, 1988). Expanded Eocene and lower-to-middle Miocene sections in the Trujillo Basin are reduced or absent in the Lima Basin, either because the Trujillo Basin received more sediments during these times, or the Lima Basin strata were more effectively stripped during subsequent orogenic movements.…”