ALBERT

Description: We report paleomagnetic data for the Lower to Middle Jurassic La Silla and Todos Santos formations of southern Mexico, in west-central Chiapas and the Tehuantepec Isthmus region. Volcanic rocks and red beds of these formations were deposited prior to or during the early stages of Gulf of Mexico opening. Dual-polarity characteristic magnetizations reside primarily in hematite and pass intraformational conglomerate, regional tilt, and reversal tests; they are thus interpreted as primary magnetizations. Our sampling sites are concentrated in three localities; around La Angostura Lake, 17 accepted sites yield a tilt corrected mean of declination (Dec) = 325{degrees}, inclination (Inc) = 4.6{degrees} (k = 11.9, {alpha}95 = 10.8{degrees}); in the Matias Romero region, the mean is Dec = 312.9{degrees}, Inc = 3.2{degrees} (based on only seven sites); and in the Custepec area, Jurassic andesitic dikes intruding rocks of the Permian Chiapas Massif yield a corrected mean of Dec = 335.0{degrees}, Inc = 5.0{degrees} (six sites). The mean directions are discordant with respect to expected North America reference directions, and indicate a counterclockwise rotation of 35{degrees} to 40{degrees}. Inclinations indicate deposition or emplacement at near equatorial paleolatitudes (2.1{degrees}N {+/-} 3.4{degrees}). This paleolatitude estimate is statistically indistinguishable from those previously observed in the La Boca Formation of the Huizachal Group in northeast Mexico. The localities we sampled in southern Mexico are separated by [~]150 km, suggesting that the paleomagnetic signature of these rocks reflects regional-scale rather than local deformation. These Jurassic paleomagnetic directions support a rotational origin for the Gulf of Mexico. The data are also consistent with an Early to Middle Jurassic reconstruction that places the Chiapas Massif offshore the Tamaulipas state in the western Gulf of Mexico, and an Euler rotation pole for the Maya Block for this time period in the eastern gulf. The apparent polar wander path defined by paleomagnetic poles for the Chiapas Massif and Jurassic rocks reported here suggests that relative motion between North America and the Maya Block occurred between Late Permian and Early Jurassic time, during a protracted rifting phase, and then in the Late Jurassic in association with seafloor formation in the Gulf.

Description: This study characterizes Miocene chronostratigraphy and plays in the Burgos Basin and adjacent south Texas within an area of approximately 39,700 km2 (15,300 mi2), onshore and offshore (to the 500-m [1640-ft] isobath). Using greater than 40,000 linear kilometers (25,000 mi) of two-dimensional seismic lines, 115 onshore wells, 9 offshore wells, and paleontological data, we established a correlation framework of 9 key surfaces (upper Oligocene to lower Pliocene) representing major (probably third-order) sequence boundaries and maximum flooding surfaces throughout the basin. Five of the Burgos Miocene surfaces coincide with regional chronostratigraphic surfaces from the Veracruz and Laguna Madre-Tuxpan basins, thus establishing a consistent correlation framework throughout much of the Mexican Gulf Coast Basin. Twenty Miocene plays are defined by four age divisions (lower Miocene, middle Miocene, upper Miocene\_1, and upper Miocene\_2) and four paleogeographic settings (unexpanded and expanded shelf, proximal slope, and distal slope). Because of proven high productivity in salt-bounded basins in the northern Gulf of Mexico, the onlap of strata onto diapirs in the eastern Burgos salt province was evaluated as a fifth setting. The paleogeographic provinces and onlap areas exhibit characteristic seismic facies, stratal geometries, and structural relations; a characterization of each one of these being key to the overall play evaluation. This play framework provides the means for continuing exploration of Miocene strata and evaluation of key play elements (reservoir presence and quality, seal, trap, source, and migration and timing) in this structurally complex, underexplored basin. The relative importance of these play elements varies systematically for each play, especially between the onshore shelf plays and the offshore deep-water plays, where fault complexity and stratigraphic variability are greater. J. Javier Hernández-Mendoza is a geoscientist, specializing in regional geology, for Pemex Exploración y Producción (PEP) in the Burgos Basin. He has worked for PEP since 1986, conducting studies at the prospect and play levels in the Burgos Basin. He holds a geologist engineer title from Tecnológico de Ciudad Madero and an M.S. degree in geological sciences from the University of Texas at Austin. Tucker F. Hentz is a sedimentary geologist specializing in siliciclastic sequence stratigraphy and basin analysis. He received his M.S. degree in geology from the University of Kansas in 1982. He joined the Bureau of Economic Geology in 1982 and has conducted studies in several mid-Continent and Gulf Coast basins. Michael V. DeAngelo is a geophysicist specializing in seismic interpretation. He received an M.S. degree in geophysics from the University of Texas at El Paso in 1988. He joined the Bureau of Economic Geology in 1998 and has been working on a variety of onshore and offshore reservoir characterization projects. Tim F. Wawrzyniec is a structural geologist specializing in kinematic analysis and geophysics. He received his Ph.D. from the University of New Mexico in 1999 and worked for Vastar and the Bureau of Economic Geology. In 2003, he joined the Department of Earth and Planetary Sciences at the University of New Mexico. Shinichi Sakurai is a senior petrophysical advisor with Occidental Mukhaizna L.L.C. From 2000 to 2006, he worked for the Bureau of Economic Geology, providing petrophysical support for various projects. He is a member of the Society of Petrophysicists and Well Log Analysts, serving as board member, distinguished speaker, and symposium chair. He specializes in petrophysical evaluation of carbonates and enhanced-oil-recovery analysis. He received his B.S. degree in geology from the Tohoku University, Sendai, Japan. Suhas C. Talukdar is a geologist-geochemist with more than 35 years of professional experience in the industry, research, and teaching. He received his Ph.D. from Rice University in 1973. His expertise is in petroleum geochemistry, basin modeling, petroleum system analysis, hydrocarbon charge assessments for plays and prospects, and integrated basin studies. He is presently a senior geochemist with Baseline Resolution, Inc. Mark H. Holtz, formerly with the Bureau of Economic Geology, is a reservoir engineer. He currently serves as the director of International Enhanced Oil Recovery Business Development for Praxair. Mark has worked on primary- and secondary-recovery projects in the United States, Australia, Venezuela, Argentina, Mexico, India, China, and Austria. He holds an M.S. degree in petroleum engineering from the University of Texas at Austin.

Description: Neogene shelf, slope, canyon, and slope-to-basin-floor transition plays in the southern Laguna Madre–Tuxpan (LM-T) continental shelf reflect a variety of structural and stratigraphic controls, including gravity sliding and extension, compression, salt evacuation, and lowstand canyon and fan systems. The Neogene in the LM-T area was deposited along narrow shelves associated with a tectonically active coast affected by significant uplift and erosion of carbonate and volcanic terrains. This study characterizes 4 structurally defined trends and 32 Neogene plays in a more than 50,000-km2 (19,300-mi2) area linking the Veracruz and Burgos basins. The Cañonero trend in the southern part of the LM-T area contains deep-seated basement faults caused by Laramide compression. Many of these faults are directly linked to the interpreted Mesozoic source rocks, providing potential pathways for vertically migrating hydrocarbons. In contrast, the Lankahuasa trend, north of the Cañonero trend, contains listric faults, which detach into a shallow horizon. This trend is associated with thick Pliocene shelf depocenters. The dominant plays in the Faja de Oro–Náyade trend in the central part of the LM-T area contain thick lower and middle Miocene successions of steeply dipping slope deposits, reflecting significant uplift and erosion of the carbonate Tuxpan platform. These slope plays consist of narrow channel-fill and levee sandstones encased in siltstones and mudstones. Plays in the north end of the LM-T area, in the southern part of the Burgos basin, contain intensely deformed strata linked to salt and shale diapirism. Outer-shelf, slope, and proximal basin-floor plays in the Lamprea trend are internally complex and contain muddy debris-flow and slump deposits. Risk factors and the relative importance of play elements vary greatly among LM-T plays. Reservoir quality is a critical limiting play element in many plays, especially those in the Cañonero trend directly downdip from the trans-Mexican volcanic belt, as well as carbonate-rich slope plays adjacent to the Tuxpan platform. In contrast, trap and source are low-risk play elements in the LM-T area because of the abundance of large three-way and four-way closures and the widespread distribution of organic-rich Upper Jurassic Tithonian-age source rock. The potential for hydrocarbon migration in LM-T plays is a function of the distribution of deep-seated faults inferred to intersect the primary Mesozoic source. Their distribution is problematic for the Lankahuasa trend, where listric faults sole out into the Paleocene. Seal is poorly documented for LM-T plays, although the presence of overpressured zones and thick bathyal shales is favorable for seal development in middle and lower Miocene basin and slope plays. William A. Ambrose is a stratigrapher specializing in clastic sedimentology. He received an M.A. degree from the University of Texas at Austin in 1983. He worked for the Research Planning Institute, Texas, from 1984 to 1986 and has been with the Bureau of Economic Geology since 1987, working on a variety of international and Gulf Coast reservoir-characterization and basin-analysis projects.Tim F. Wawrzyniec is a structural geologist specializing in kinematic analysis and geophysics. He received his Ph.D. from the University of New Mexico in 1999 and worked for Vastar and the Bureau of Economic Geology. In 2003, he joined the Department of Earth and Planetary Sciences at the University of New Mexico. Khaled Fouad has been a senior seismic interpreter at the Bureau of Economic Geology since 1997. He has more than 17 years experience as a seismic interpreter with various major oil companies. He received his B.Sc. degree in 1982 in Alexandria University, Egypt. He received his Diploma of higher studies in 1984 with honors from the same university. His experience includes the Gulf of Mexico, Maracaibo Basin, Vienna Basin, and the Gulf of Suez. Shinichi Sakurai is a petrophysicist and was employed by ARCO Technology & Operation Services before joining the Bureau of Economic Geology in July 2001. He also worked for Core Laboratories, Inc., and BP. He has served the Society of Petrophysicists and Well Log Analysts as a distinguished speaker, a technology committee member, and a symposium-organizing committee member. David Jennette has 15 years of industry experience in nonmarine, shelf, and deepwater reservoir prediction and characterization for ExxonMobil Upstream Research Company; since coming to the Bureau of Economic Geology, he has been involved in high-resolution digital outcrop capture and interpretation and play assessment and characterization of Petroleos Mexicanos' turbidite-dominated Veracruz basin. L. Frank Brown received his B.S. degree in geology and chemistry from Baylor University in 1951 and his M.S. degree and his Ph.D. from the University of Wisconsin in 1953 and 1955, respectively. In addition to serving as associate director and research professor for the Bureau of Economic Geology, Frank has worked for Standard Oil of Texas and has served as an associate professor at Baylor University and emeritus professor at the University of Texas at Austin. Frank has authored numerous publications and has received numerous awards. Edgar H. Guevara is a research scientist at the Bureau of Economic Geology; he previously worked in the Venezuelan petroleum industry. He holds geological degrees from the Universidad Central Venezuela and the University of Texas at Austin (M.A. and Ph.D.). He has more than 35 years of experience in geological studies and project coordination, particularly depositional systems and stratigraphy applications to petroleum exploration, reservoir characterization, and geoenvironmental studies. Dallas B. Dunlap is a geologist and database coordinator for the Bureau of Economic Geology. He received a B.S. degree from the University of Texas at Austin in 1997 and has been employed by the Bureau of Economic Geology since that time. He has worked on many international and domestic projects, focusing on subsurface mapping, modeling, and data management. Suhas C. Talukdar is a geologist-geochemist with 35 years of professional experience in industry, research, and teaching. He received a Ph.D. in 1973 from Rice University, Houston. His expertise is in petroleum geochemistry, basin modeling, petroleum system analysis, and hydrocarbon charge assessment. He is presently a consultant with the Bureau of Economic Geology and BaselineDGSI at Woodlands, Texas. Mario Aranda Garcia is a structural geologist with more than 20 years experience with Petroleos Mexicanos. He holds advanced degrees in geology from the Universidad Nacional Autonoma de Mexico and the University of Texas at Austin. He specializes in tectonics and fault modeling applied to exploration. He was Petroleos Mexicanos' principal investigator for the recent Bureau of Economic Geology–Petroleos Mexicanos joint research project on the offshore Laguna Madre–Tuxpan area. Ulises Hernández Romano is a geologist with Petroleos Mexicanos Exploración y Producción. He graduated with honors from the Universidad Nacional Autonoma de Mexico in 1995. In 1999, he obtained a Ph.D. in sedimentology from the Postgraduate Research Institute for Sedimentology, University of Reading, United Kingdom. He joined Petroleos Mexicanos Exploración y Producción in 1999 and currently is leading the offshore development team in the Poza Rica area. He is currently the vice-president of the Poza Rica section of the Asociacion Mexicana de Geologos Petroleros. Juan Alvarado Vega is a geologist with Petroleos Mexicanos Exploración y Producción. He has been active at the Tampico office for more than 5 years. During the Bureau of Economic Geology–Petroleos Mexicanos joint research project on the offshore Laguna Madre–Tuxpan area, he was responsible for

Description: The Miocene and Pliocene interval of the Veracruz Basin, southeast Mexico, experienced an evolving array of shortening, strike-slip, and volcanic forces in response to plate-scale interactions. The basin is divided into six structural domains that define regions of comparable timing and type of structural deformation, and the basin fill is separated into two long-term depositional phases, each of which can be tied to a waning and then waxing of major basin-bounding tectonic events. The first phase of deposition took place from the early to late Miocene and is tied to the waning effects of the Laramide orogeny. The Miocene basin inherited a tectonically steepened basin margin, across which deep canyons were carved and variably filled with mudstone and thin remnants of coarse sandstone and conglomerate. This zone of erosion and bypass grades into thick, sandstone-rich basin-floor fans. Later in phase I, subaqueous volcanoes, tied to distant plate subduction, developed offshore and formed a bathymetric barrier that prevented turbidity currents from entering the ancestral Gulf of Mexico. The volcanoes also served as immovable buttresses, around which intrabasinal thrust belts developed in response to regional shortening. The second depositional phase is tied to the onset of internal basin shortening and uplift of the north basin margin known as the trans-Mexican volcanic belt. This uplift caused a dramatic reconfiguration of the sediment-dispersal system, whereby large shelf clinoforms prograded from north to south across the basin. In contrast to the onlapping stacking pattern of phase I units, phase II units stack in a strongly offlapping pattern. Proven and postulated reservoir-trap combinations, ranging from four-way to three-way combination (stratigraphic), to pure stratigraphic traps are common. Four-way closures mapped from the two-dimensional and three-dimensional seismic data are large (P50: 5000 km2) and are covered with thick, lower Miocene fan sandstones. Traps that depend on a stratigraphic component are thinner and smaller in size (P50: 1000 km2), but more numerous than the four-way closures. Because many structures have experienced prolonged pulses of compression, top seal is considered an important geologic risk to the retention of substantial gas-column heights. David C. Jennette received a B.S degree from Allegheny College and an M.S. degree from the University of Cincinnati. He is currently a program director at the Bureau of Economic Geology, conducting a range of studies on siliciclastic basins, reservoirs, and outcrops. Previously, he was a senior research geologist at ExxonMobil's Upstream Research in their Deepwater Reservoirs Research Group. He maintains a research focus on multidisciplinary analyses of turbidite reservoir systems.Tim F. Wawrzyniec is a structural geologist specializing in kinematic analyses and geophysics. He earned his Ph.D. from the University of New Mexico in 1999 and joined the Bureau of Economic Geology in 2000. Tim is currently a senior research scientist at the University of New Mexico and continues to work with the Bureau of Economic Geology on several basin analysis projects. Khaled Fouad is a senior researcher responsible for seismic interpretation and visualization technology. Before joining the Bureau of Economic Geology in 1997, he worked over 14 years as a seismic interpreter with various major oil companies where he gained experience in the Gulf of Mexico, Maracaibo Basin, Vienna Basin, and Gulf of Suez basins. Khaled received his B.Sc. degree in 1982 from Alexandria University, Egypt, and a Diploma of Higher Studies in 1984. Dallas B. Dunlap is a geologist and database coordinator for the Bureau of Economic Geology. He received a B.S. degree from the University of Texas at Austin in 1997. He has worked on many international and domestic projects that focus on subsurface mapping, 3-D visualization, modeling, and data management. Javier J. Meneses-Rocha received a B.S. degree in geological engineering in 1976 and earned his M.A. degree and his Ph.D. in geology from the University of Texas at Austin in 1985 and 1991, respectively. Meneses-Rocha started with Pemex in an 1985 as field geologist and then worked on regional petroleum evaluation projects, planning, reserve evaluation, prospect evaluations, and structural and play analysis projects. He is now manager of Geological and Geophysical Integration and Interpretation for Pemex Exploración and Producción. He is the past president of the Asociación Mexicana de Geólogos Petroleros. Francisco is a geologist and petrophysicist presently developing prospects and interpreting drillwell data from northern Veracruz Basin. Rafael Munoz is a geophysical interpreter identifying prospects and drilling exploration wells in the northern Veracruz Basin. David Barrera received a geologist engineering degree from the Instituto Politecnico Nacional in 1982. He has worked in Pemex for 15 years conducting petroleum systems, play, and prospect analysis. He is currently the team leader of the southern Veracruz exploration project in the Activo Salina del Istmo. Carlos T. Williams-Rojas is a geologist working on stratigraphy, basin, and play analysis, and economic evaluation. He earned an M.S. degree from Universidad Nacional Autonoma de Mexico in 1995 and an M.S. degree from Colorado School of Mines in 2000. Carlos is currently a senior geologist working for Pemex in the Activo Salina del Istmo. Arturo Escamilla-Herrera is a geologist conducting seismic interpretation, basin, and play analysis, and formation evaluation. He earned a B.S. degree from Instituto Politecnico Nacional in 1985 and is candidate for an M.S. degree in the same institution. Arturo is currently a senior geologist working for Pemex in the Activo Salina del Istmo.

Description: Major Miocene structural elements of the Burgos Basin include a regionwide detachment system that connects extensional fault systems throughout the basin with an active diapir belt downdip, a regionwide pattern of downthrown extensional rollover folds, pervasive secondary faults, and salt and shale diapiric masses in the eastern part of the basin. An interpretation of two-dimensional seismic data suggests that the Burgos Basin Miocene section can be divided into four structural domains: expanded zone, Lamprea trend, Corsair-Wanda trend, and diapir belt. The westernmost unexpanded zone is the footwall of the expanded system part of the basin, which overlies a domain of Oligocene extension. Remaining trends represent an extensional accommodation related to the basinward migration of mobile salt and shale, which has produced a relatively uniform structural style in the Miocene section. The structural style observed in the Burgos Basin appears to define a transitional zone between gravitational collapse in the offshore Laguna Madre-Tuxpan shelf to the south and salt-related raft tectonics of the south Texas Gulf Coast. J. Javier Hernández-Mendoza is a geoscientist, specializing in regional geology, for Pemex Exploración y Producción (PEP) in the Burgos Basin. He has worked for PEP since 1986, conducting subsurface and surface geological studies at the prospect and play levels in the Burgos Basin. He holds a geologist engineer title from Tecnológico de Ciudad Madero and an M.S. degree in geological sciences from the University of Texas at Austin. Michael V. DeAngelo is a geophysicist specializing in seismic interpretation. He received an M.S. degree in geophysics from the University of Texas at El Paso in 1988. He joined the Bureau of Economic Geology in 1998 and has been working on a variety of onshore and offshore reservoir characterization projects. Tim F. Wawrzyniec is a structural geologist specializing in kinematic analysis and geophysics. He received his Ph.D. from the University of New Mexico in 1999 and worked for Vastar and the Bureau of Economic Geology. In 2003, he joined the Department of Earth and Planetary Sciences at the University of New Mexico. Tucker F. Hentz is a research scientist associate at the Bureau of Economic Geology, which he joined in 1982. Past and present research interests include regional sequence stratigraphy and reservoir geology of hydrocarbon-bearing successions in the Anadarko Basin, East Texas Basin, Rio Grande embayment, Fort Worth Basin, and northern Gulf Coast Basin. He graduated cum laude with a B.A. degree in geology from Franklin and Marshall College in 1977 and received his M.S. degree in geology from the University of Kansas in 1982.