Fault-controlled fluid migration and cold seep distribution in the offshore Talara and Tumbes basins, NW Peruvian Margin

Abstract

Cold seeps along convergent margins provide key insights into subsurface fluid migration and active petroleum systems, yet the structural controls governing their distribution remain poorly constrained in forearc basins. This study investigates the morphostructural framework controlling cold seeps and hydrocarbon migration along the northwestern Peruvian margin by integrating new multibeam bathymetry, 2D multichannel seismic reflection profiles, and hydroacoustic data from the offshore Talara and Tumbes basins. Four morphostructural domains (Paita, Talara, Tumbes, and Peru Bank) are defined based on major fault systems, basin architecture, and seafloor morphology. A total of 613 cold seep-related seabed geoforms, including pockmarks, mounds, and inferred mud volcanoes, were mapped across the study area. Hydroacoustic data reveal active gas flares sourced from Cretaceous and Eocene reservoirs in the Talara Basin and Lower Miocene units in the Tumbes Basin. A continuous bottom-simulating reflector (BSR) beneath the Talara Basin slope marks the base of the gas hydrate stability zone, with underlying high-amplitude anomalies indicating free gas accumulation. Deep listric, strike-slip, and normal faults provide the principal pathways for hydrocarbon migration from deep reservoirs to the seafloor. The strong spatial association between cold seeps and known hydrocarbon accumulations confirms the presence of active petroleum systems and demonstrates that regional fault architecture exerts a first-order control on fluid migration. These findings demonstrate that fault systems control fluid migration from deep reservoirs to the seafloor, offering a predictive framework for identifying hydrocarbon-prospective zones in forearc basins.