Abstract Prospect Serrano is located approximately 220 miles southwest of New Orleans and 6 miles southeast of the Auger TLP in Garden Banks Block 516. The Shell GB 516 #1 well, drilled in 1996, has encountered 86 net feet of Pleistocene age (P. lacunosa) gas pay at the main objective horizon. The objective horizon occurs in the largely channelized bypass seismic facies assemblage (e.g ., Prather et al ., 1998), and is mapped regionally as a highly continuous draping seismic event. In offset penetrations the objective horizon is sand lean and generally associated with pyroclastic sediments. Mapping of 3D seismic data and comparisons to the present day seafloor, however, suggest a sand-prone depositional setting at the Serrano prospect. Loop level attributes and interval isochores indicate that several depositional systems were active at Serrano. In addition, present day seafloor bathymetry reveals the presence of a backstop setting within low-relief ponded accommodation space (e.g ., Prather et al ., 1998). Furthermore, images of the present day seafloor support the interpretation of multiple sediment entry points and offer clues to depositional and erosional relationships preserved in the subsurface. The seafloor analogue is instrumental to understanding the distribution of sheet sands, depositional and erosional bypass channel systems, debris flows, and large-scale erosional gorge systems at the Serrano prospect. The seafloor is a present-day analogue of Pleistocene depositional processes in the Gulf of Mexico and is a valuable tool in reservoir prediction. Some of the terminology used in this paper is common within Shell, but less well known in the oil industry in general. The following table defines some of this terminology.

Abstract Introduction The Lisheen deposit, County Tipperary, Ireland is a stratiform Zn-Pb deposit hosted in dolomitized Waulsortian limestone of Courceyan age. Lisheen is situated 130km southwest of Dublin and 10km northeast of Thurles, the nearest town (Fig. 1). Lisheen was discovered in April 1990 and the current resource is estimated to be 22.2Mt at 11.5% Zn, 1.9% Pb and 16% Fe, with 26 g/t Ag. The deposit is located close to the southeastern edge of the Rathdowney Trend, a 40km long northeast-southwest trending belt of carbonate rocks extending from Abbeyleix in County Laois to Thurles in County Tipperary (Fig. 1). A number of base metal deposits and sub-economic occurrences are hosted in the Lower Carboniferous limestones of the Rathdowney Trend. The Lisheen deposit lies southwest of the Galmoy deposit (Doyle et al. 1992). The Lisheen deposit is similar to the Silvermines zinc-lead deposit (10.7 Mt at 7.36% Zn and 2.70% Pb). Base metal mineralization at Lisheen occurs principally in the hangingwall rocks of the Killoran and Derryville faults (Fig. 3). These east-west trending normal faults, with maximum displacements of approximately 200m, formpart of amajor 40km long relay fault system which extends along the Rathdowney Trend. The deposit consists of three principal zones of mineralization, the Main, Derryville and North zones. Mineralization extends 2km along the strike length of the fault system and approximately 1.5km to the north, in the hangingwall. Mineralization occurs as a series of massive to semi-massive stratiform sulfide lenses, as irregular zones of breccia/vein style sulphides and as