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Petrophysics and Well Logs

Search and Discovery Article

Measurements of fluid wetting characteristic are made routinely on rock samples. However, there are no published petrophysical models to differentiate between oil-wet and water-wet fractions of a reservoir sequence using commonly available log suites. This presentation builds on our previous publication that describes the unconventional reservoir petrophysical model we have developed (Holmes, 2014). Essentially, we define four porosity components, namely total organic carbon, clay porosity, effective porosity, and “free shale porosity.” This last component is an indirect calculation if the first three components do not sum to total porosity.  Porosity/resistivity plots can be constructed for the total porosity and interpreted in a standard fashion. These will mostly indicate a water-wet system where the effective porosity fraction is examined. A second porosity/resistivity plot compares resistivity with “free shale porosity,” and is clearly interpreted to indicate Archie saturation exponents of much larger than 2 — frequently in excess of 3 — indicating the oil-wet fraction of the reservoir system. Additionally, the plots suggest low to very low values of cementation exponent, ranging from 1.0 to 1.5.   Examples from the Bakken of Montana and North Dakota, the Niobrara of Colorado, and the Wolfcamp and Spraberry of Texas are presented showing quantitative distinction of water-wet vs. oil-wet reservoir components.

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American Association of Petroleum Geologists (AAPG)
Explorer Article

The forum will include presentations given by leading experts from companies who have been successfully operating in the basin.

American Association of Petroleum Geologists (AAPG)
Explorer Article

Thanks to advancements in data management and seismic sensing, geophysical modeling has become indispensable in the search for oil. What will it become in the century ahead?

American Association of Petroleum Geologists (AAPG)
PSGD Blog

The AAPG Petroleum Structure and Geomechanics Division (PSGD) has announced the 2016 Best Paper Awards at the Annual Convention and Exhibition in Calgary, Alberta, Canada. Congratulations to Richard H Groshong, Jr., awarded 'Best Seminal Publication' for '3-D Structural Geology: A Practical Guide to Quantitative Surface and Subsurface Map Interpretation 2nd Edition'. We thank everyone for nominating the candidates. We also thank Bob Krantz, Bob Hatcher, and Gary Couples for their diligent work on the PSGD Best Paper Committee.

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American Association of Petroleum Geologists (AAPG)
Learn! Blog

Optimizing reservoirs and developing an ever-evolving intelligent model of a reservoir are key concerns for operators, particularly in challenging times. For that reason, they must have good production geologists on hand. A production geologist bridges a number of disciplines, most notably geology and engineering, but also geochemistry, geophysics, and numerical methods. Welcome to an interview with Terngu Utim who discusses production geology, its new potential and opportunities.

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American Association of Petroleum Geologists (AAPG)
Learn! Blog

The dynamics of fluid behavior and structural movement on the nano-scale can be complicated and not always what was expected. New research that analyzes the well information and cores using new techniques and technologies is yielding important and useful results. Welcome to an interview with Wen Zhou, Chengdu University of Technology, who discusses recent research findings.

American Association of Petroleum Geologists (AAPG)
Learn! Blog

Primary research in hydrocarbon generation is yielding new insights into the natural gas geochemical characteristics of conventional and unconventional reservoirs, along with discoveries relating to the geomechanical processes. Welcome to an interview with Chenglin Liu, China University of Petroleum-Beijing, who discusses enlightening new findings regarding the relationship between salinity and hydrocarbon geochemical characteristics.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

Understanding the complex makeup of reservoirs is essential, and it requires considerable evaluation and time.

American Association of Petroleum Geologists (AAPG)
Learn! Blog

How does diagenesis affect rock physics? What is the relationship of the burial history to the rock physics? Both have a dramatic impact on the rock physics properties of not only the reservoir, but also the source and seals. Welcome to an interview with Per Avseth, who discusses rock physics and quantitative seismic interpretation. He also talks with us about how developing an effective rock physics model requires the integration of geological, geophysical, geochemical, and petrophysical information.

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American Association of Petroleum Geologists (AAPG)
Learn! Blog

You may not be aware that there was a super-Greenhouse environment during the Cretaceous, and that there were super-storms associated with it, and that analyzing the sediments deposited during that time can provide insight into the potential warming of climates, and also the cross-shelf transport of sediments. That is just one of many fascinating new areas of research that looks at data through new lenses, and with new analytical techniques. Welcome to an interview with Lesli J. Wood, Weimer Distinguished Chair and Professor in Sedimentary and Petroleum Geology, Colorado School of Mines.

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American Association of Petroleum Geologists (AAPG)
Workshop
Muscat, Oman
Monday, 6 April Wednesday, 8 April 2026, 8:00 a.m.–5:00 p.m.

The AAPG Structural Styles of the Middle East is back! This exciting and highly anticipated Geoscience Technology Workshop will take place from 6 – 8 April 2026, in Muscat, Oman. This workshop aims to explore the diverse structural styles resulting from the different deformation phases on the tectonostratigraphic framework of the Arabian Plate and adjacent regions.  

American Association of Petroleum Geologists (AAPG)
Field Seminar
Muscat, Oman
Sunday, 5 April 2026, 8:00 a.m.–4:30 p.m.

This one-day advanced course delivers a focused and highly practical framework for interpreting structural styles in the Middle East, combined with the unique advantage of applying Generative AI (GenAI) to elevate geological understanding and decision-making. Built for geoscientists working in exploration, development, or basin modeling, the course emphasizes practical techniques, hands-on interpretation, and modern tools that increase accuracy, speed, and confidence in structural workflows. We begin with a foundational module designed to unify all participants, regardless of background, around the principles of fault mechanics and structural style recognition. Participants will revisit faulting fundamentals, mechanical stratigraphy, and structural style classification. The goal is to align interpretation techniques with geological processes, and to establish a shared vocabulary for the day. An introduction to GenAI highlights its role in managing structural ambiguity and enhancing workflows, helping geoscientists clarify options when data is incomplete or conflicting. Normal Faulting Through a sequence of focused exercises, participants explore fault segmentation, growth history, and interpretation in extensional domains. This segment reinforces practical skills in identifying and validating fault geometries in map and section views. GenAI is introduced as a scenario-building tool: participants will use it to explore structural uncertainty, generate alternative models, and compare extensional interpretations, all using fragmented or incomplete datasets, not as a seismic interpreter but as a powerful thought partner. Strike-Slip and Transtension This module targets the complexity of strike-slip and transtensional systems. Participants learn to distinguish pure strike-slip geometries from transtensional overprints, assess compartmentalization, and model realistic deformation patterns. Interpretation exercises develop structural reasoning in map and cross-sectional views. GenAI is applied here to integrate multi-source inputs, such as field data, analogs, and internal reports, to support rapid synthesis and generate testable structural concepts. Salt Tectonics The final segment introduces key diagnostic features of salt-related deformation: welds, reactive and passive diapirs, and halokinetic sequences. Exercises train participants to recognize salt-influenced geometries and link them to broader structural evolution. GenAI then supports pattern recognition and memory mining, leveraging archived knowledge from prior studies, case histories, and analog reports to help geoscientists build and validate interpretations faster and with more confidence. What makes this course different? This is not a theoretical seminar. It’s a learning accelerator, where foundational concepts are applied in realistic interpretation settings, then extended with state-of-the-art GenAI capabilities. You’ll not only sharpen your structural reasoning, but learn how to delegate time-consuming tasks, like synthesizing legacy reports, generating alternative scenarios, or exploring interpretation options, to an intelligent AI partner. By the end of the day, participants will: Recognize and differentiate key fault styles with confidence Improve fault interpretation quality and geological risk assessment Use GenAI to test structural scenarios and extract insight from fragmented or incomplete datasets Accelerate their ability to interpret, communicate, and make decisions in structurally complex plays This course equips you with what matters most today: deep geological understanding, elevated by the best of modern AI. Who Should Attend and Why This course is ideal for both new hires and experienced geoscientists working across exploration, development, and reservoir modeling. Its exercise-driven format ensures that participants with diverse backgrounds, geologists, geophysicists, geomodelers, can engage, learn, and apply. While some familiarity with geosciences is beneficial, prior structural geology training is not required. What makes this course indispensable is its ability to bridge theory and practice: participants will gain a clear understanding of how rocks deform over time, how fault geometries evolve, and how these structures influence seismic interpretation, mapping, and static/dynamic modeling. By integrating real case studies and GenAI-enhanced workflows, the course delivers practical tools to improve subsurface outcomes and build models that match project maturity and business objectives. Main Objective This course delivers the structural geology foundations every geoscientist needs to confidently interpret faults and build or validate static models. Derived from decades of project reviews, interpretation support, and applied field experience, these “must-know” concepts include fault mechanics, growth, segmentation, and structural style recognition, relevant to both exploration and production settings. Participants will strengthen their ability to recognize deformation styles, interpret fault geometries in map and section view, assess mechanical stratigraphy and reactivation risk, and QC interpretations with confidence. Throughout the course, GenAI is introduced not as a software tool, but as a workflow enhancer, used to reduce ambiguity, test structural hypotheses, and extract insight from fragmented datasets or legacy documentation. This empowers geoscientists to think more clearly, work more efficiently, and improve the geological soundness of their models. Key Points Date: 5th April,2026 Venue: Crowne Plaza Hotel, OCEC Registration Fee: $590 Registration Deadline: 22nd February,2026 *Registration will be opening shortly Instructors Pascal Richard PRgeology Jan Witte Falcon-Geoconsulting

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American Association of Petroleum Geologists (AAPG)
Field Seminar
Muscat, Oman
Thursday, 9 April Friday, 10 April 2026, 7:30 a.m.–7:00 p.m.

The Jabal Akhdar in the Central Oman Mountains forms a ~90 km × 60 km dome. The core of this dome consists of Cryogenian to Ediacaran siliciclastics and carbonates, including source rocks. These rocks are separated from the overlying rocks by a spectacularly exposed angular unconformity. The rocks above this unconformity are Permo-Mesozoic shelf carbonates of the Arabian passive margin. The rocks below the unconformity are folded twice, while those above show no such folding. During the Late Cretaceous, Arabia was overthrust by the Samail Ophiolite and Hawasina deep-sea sedimentary rocks. Final doming occurred during the late Eocene to early Miocene. The Jabal Akhdar Dome is a textbook example of stratigraphy and structural geology development from the Cryogenian to the present. Furthermore, findings from the dome can be used as a natural laboratory and serve as an analogue for the hydrocarbon-bearing sequences in interior Oman. The two-day field trip will start at the Saiq Plateau where we will examine Cryogenian Snowball-Earth diamictites with cap carbonates, blended within the scenic landscape of Jabal Akhdar. The second day will start at a breath-taking vista point at Wadi Bani Awf. From there we will descend into the core of the Jabal Akhdar and explore the structural style of the Cryogenian and younger succession. Field Trip Information: Date: 9th – 10th April 2026 Time: 7:30am – 7pm Field Trip fee: $550 Registration Deadline: 5th March 2026 (*registration will be opening shortly) Fees Include: 1 night accommodation in a hotel Guided hiking tour through rose farms and ancient villages in Jebel Akhdar (2–3 hours) Traditional Omani lunch hosted at a local home BBQ dinner in a scenic open area at Jebel Akhdar All transportation (4x4s) Field Trip Leaders Ivan Callegari GUtech Oman Wilfried Bauer GUtech Oman Andreas Scharf Sultan Qaboos University

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American Association of Petroleum Geologists (AAPG)
Webinar
Virtual Webinar
Wednesday, 9 February 2022, 8:00 a.m.–9:00 a.m.

 This talk will provide information to better understand the principles of surface geochemistry (SG), how best to use SG data in exploration or development programs, how to develop a cost effective sampling and analytical program, and will also explore best practices for the interpretation and integration of SG data.

American Association of Petroleum Geologists (AAPG)
Webinar
Virtual Webinar
Thursday, 28 October 2021, 10:00 a.m.–11:00 p.m.

As an industry we’re constantly challenged to improve our business on a worldwide stage. How do we continue improving the safe delivery of high quality, economical wells and production where understanding of social requirements and the license to operate are rapidly changing? Join us for a conversation with a panel of drilling engineers to gain insight to their understanding of how we can meet these challenges and impact well delivery planning processes and outcomes - from clarity on deliverables, process improvements, advances in technology, to building better business models for modern decision making.

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American Association of Petroleum Geologists (AAPG)
Online e-Symposium
Thursday, 30 October 2014, 10:00 a.m.–11:00 a.m.

Cross disciplinary workflows play an important part of successful characterization of shale reservoirs. This course discusses how the artificial kerogen maturity of organic-rich Green River shale affects the petrophysical, micro-structural, geochemical and elastic properties.

American Association of Petroleum Geologists (AAPG)
Webinar
Virtual Webinar
Tuesday, 14 July 2020, 11:00 a.m.–12:00 p.m.

The Santos Basin is an excellent example of how much oil is kept in remote sites, just waiting to be found by bold explorationists with the will and resources needed to find them. Join Flávio Feijó to for a presentation of the history and potential for future discoveries in the Santos Basin Webinar will be presented via Zoom on Tuesday 14 July 2020 at 11am CDT (UMT-6). Register Now at Zoom

American Association of Petroleum Geologists (AAPG)
Webinar
Virtual Webinar
Thursday, 24 September 2020, 8:30 p.m.–9:30 p.m.

In the past 3 decades the sequence stratigraphy jargon has proliferated, resulting in multiple definitions of the same surface or new surfaces and units based on drawings of deposition in response to relative changes in sea level. The close association between base-level changes, the formation of surfaces, and specific stratal stacking that define systems tracts are at the heart of the confusion. This webinar is proposed a back-to-basics approach, emphasizing key observations that can be made from any geologic data: lithofacies, lithofacies association, vertical stacking, stratal geometries, and stratal terminations.

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American Association of Petroleum Geologists (AAPG)
Webinar
Virtual Webinar
Thursday, 10 September 2020, 3:00 p.m.–4:00 p.m.

Economic oil and gas fields have been increasingly found in deep-water continental margins for the past decade, where potential prospects record the key tectonic events associated with plate breakup and continental drift. In these regions, the exploitation of economic resources must take into account sustainable practices and environmental concerns of local populations. This talk will present case studies from multiple continental margins to then extrapolate major findings to basins in SE Asia.

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American Association of Petroleum Geologists (AAPG)
Webinar
Virtual Webinar
Tuesday, 1 September 2020, 8:00 a.m.–9:00 a.m.

The “Great Crew Change” has become the “Competence Train Wreck” due to the repeated personal mis-management practices of our industry and again not anticipating the known volatility of commodity prices. Despite this, hydrocarbon based energy will continue to comprise over 60% of the world’s energy mix for at least the next half century and of that energy need over half of it has yet to be found! Personal experience in working for National Oil Companies, Parastatals, large independent oil companies, small independents, as an independent and as a consultant have given me the perspective of some of the best and some of the worst of the exploration practices the industry has to offer.

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American Association of Petroleum Geologists (AAPG)
Online e-Symposium
Thursday, 29 October 2009, 12:00 a.m.–12:00 a.m.

Expanded package for CEU credit is $100 for AAPG members, and $145 for non-members. Special Student Pricing: $25 for Webinar only; $35 for Expanded package.

American Association of Petroleum Geologists (AAPG)
Webinar
Virtual Webinar
Monday, 19 October 2020, 12:00 p.m.–1:30 p.m.

In this webinar, Stephen Ehrenberg will present a review of the various processes that interact to determine the wide variations in porosity found in carbonate strata containing petroleum reserves. Presentation is via Zoom on Monday 19 October at 12:00 London time.

American Association of Petroleum Geologists (AAPG)
Webinar
Virtual Webinar
Tuesday, 30 June 2020, 1:00 p.m.–2:00 p.m.

Visiting Geoscientist Juan Pablo Lovecchio reviews general aspects of rifting, rifts and passive margin formation and evolution through time, as well as elements of petroleum system development.

American Association of Petroleum Geologists (AAPG)
DL Abstract

Physics is an essential component of geophysics but there is much that physics cannot know or address. 

Request a visit from John Castagna!

American Association of Petroleum Geologists (AAPG)
VG Abstract

Production from unconventional petroleum reservoirs includes petroleum from shale, coal, tight-sand and oil-sand. These reservoirs contain enormous quantities of oil and natural gas but pose a technology challenge to both geoscientists and engineers to produce economically on a commercial scale. These reservoirs store large volumes and are widely distributed at different stratigraphic levels and basin types, offering long-term potential for energy supply. Most of these reservoirs are low permeability and porosity that need enhancement with hydraulic fracture stimulation to maximize fluid drainage. Production from these reservoirs is increasing with continued advancement in geological characterization techniques and technology for well drilling, logging, and completion with drainage enhancement. Currently, Australia, Argentina, Canada, Egypt, USA, and Venezuela are producing natural gas from low permeability reservoirs: tight-sand, shale, and coal (CBM). Canada, Russia, USA, and Venezuela are producing heavy oil from oilsand. USA is leading the development of techniques for exploring, and technology for exploiting unconventional gas resources, which can help to develop potential gas-bearing shales of Thailand. The main focus is on source-reservoir-seal shale petroleum plays. In these tight rocks petroleum resides in the micro-pores as well as adsorbed on and in the organics. Shale has very low matrix permeability (nano-darcies) and has highly layered formations with differences in vertical and horizontal properties, vertically non-homogeneous and horizontally anisotropic with complicate natural fractures. Understanding the rocks is critical in selecting fluid drainage enhancement mechanisms; rock properties such as where shale is clay or silica rich, clay types and maturation , kerogen type and maturation, permeability, porosity, and saturation. Most of these plays require horizontal development with large numbers of wells that require an understanding of formation structure, setting and reservoir character and its lateral extension. The quality of shale-gas resources depend on thickness of net pay (>100 m), adequate porosity (>2%), high reservoir pressure (ideally overpressure), high thermal maturity (>1.5% Ro), high organic richness (>2% TOC), low in clay (<50%), high in brittle minerals (quartz, carbonates, feldspars), and favourable in-situ stress. During the past decade, unconventional shale and tight-sand gas plays have become an important supply of natural gas in the US, and now in shale oil as well. As a consequence, interest to assess and explore these plays is rapidly spreading worldwide. The high production potential of shale petroleum resources has contributed to a comparably favourable outlook for increased future petroleum supplies globally. Application of 2D and 3D seismic for defining reservoirs and micro seismic for monitoring fracturing, measuring rock properties downhole (borehole imaging) and in laboratory (mineralogy, porosity, permeability), horizontal drilling (downhole GPS), and hydraulic fracture stimulation (cross-linked gel, slick-water, nitrogen or nitrogen foam) is key in improving production from these huge resources with low productivity factors.

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Request a visit from Ameed Ghori!

American Association of Petroleum Geologists (AAPG)
DL Abstract

While there are many habitats that are associated with the deposition of organic-rich marine and lacustrine source rocks, one important pathway is linked to the onset of increased basin subsidence associated with major tectonic events. A key aspect is that this subsidence is spatially variable, with the uplift of basin flanks contemporaneous with the foundering of the basin center, resulting in a steeper basin profile.

Request a visit from Kurt W. Rudolph!

American Association of Petroleum Geologists (AAPG)
VG Abstract

The carbonate sequences that were deposited in the now exhumed Tethyan Ocean influence many aspects of our lives today, either by supplying the energy that warms our homes and the fuel that powers our cars or providing the stunning landscapes for both winter and summer vacations. They also represent some of the most intensely studied rock formations in the world and have provided geoscientists with a fascinating insight into the turbulent nature of 250 Million years of Earth’s history. By combining studies from the full range of geoscience disciplines this presentation will trace the development of these carbonate sequences from their initial formation on the margins of large ancient continental masses to their present day locations in and around the Greater Mediterranean and Near East region. The first order control on growth patterns and carbonate platform development by the regional plate-tectonic setting, underlying basin architecture and fluctuations in sea level will be illustrated. The organisms that contribute to sequence development will be revealed to be treasure troves of forensic information. Finally, these rock sequences will be shown to contain all the ingredients necessary to form and retain hydrocarbons and the manner in which major post-depositional tectonic events led to the formation of some of the largest hydrocarbon accumulations in the world will be demonstrated.

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Request a visit from Keith Gerdes!

American Association of Petroleum Geologists (AAPG)
DL Abstract

As oil and gas exploration and production occur in deeper basins and more complex geologic settings, accurate characterization and modeling of reservoirs to improve estimated ultimate recovery (EUR) prediction, optimize well placement and maximize recovery become paramount. Existing technologies for reservoir characterization and modeling have proven inadequate for delivering detailed 3D predictions of reservoir architecture, connectivity and rock quality at scales that impact subsurface flow patterns and reservoir performance. Because of the gap between the geophysical and geologic data available (seismic, well logs, cores) and the data needed to model rock heterogeneities at the reservoir scale, constraints from external analog systems are needed. Existing stratigraphic concepts and deposition models are mostly empirical and seldom provide quantitative constraints on fine-scale reservoir heterogeneity. Current reservoir modeling tools are challenged to accurately replicate complex, nonstationary, rock heterogeneity patterns that control connectivity, such as shale layers that serve as flow baffles and barriers.

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Request a visit from Tao Sun!

American Association of Petroleum Geologists (AAPG)
DL Abstract

Engineering of wind farms, development of carbon sequestration projects in shelfal waters, the proliferation of communication cables that connect the world, all of these things suggest that it is time to re-examine what we know about shelf processes both updip-to-downdip and along shoreline, and the influence of shelf processes on erosion and transport of sediments.

Request a visit from Lesli Wood!

American Association of Petroleum Geologists (AAPG)
DL Abstract

Three-dimensional (3D) seismic-reflection surveys provide one of the most important data types for understanding subsurface depositional systems. Quantitative analysis is commonly restricted to geophysical interpretation of elastic properties of rocks in the subsurface. Wide availability of 3D seismic-reflection data and integration provide opportunities for quantitative analysis of subsurface stratigraphic sequences. Here, we integrate traditional seismic-stratigraphic interpretation with quantitative geomorphologic analysis and numerical modeling to explore new insights into submarine-channel evolution.

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Request a visit from Jacob Covault!

American Association of Petroleum Geologists (AAPG)
DL Abstract

President Biden has laid out a bold and ambitious goal of achieving net-zero carbon emissions in the United States by 2050.  The pathway to that target includes cutting total greenhouse gas emissions in half by 2030 and eliminating them entirely from the nation’s electricity sector by 2035. The Office of Fossil Energy and Carbon Management will play an important role in the transition to net-zero carbon emissions by reducing the environmental impacts of fossil energy production and use – and helping decarbonize other hard-to abate sectors.

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Request a visit from Jennifer Wilcox!

American Association of Petroleum Geologists (AAPG)
DL Abstract

Paleozoic North America has experienced multiple mountain building events, from Ordovician to Permian, on all margins of the continent. These have had a profound effect on the resulting complex basins and their associated petroleum systems. Subsequent uplift, erosion and overprinting of these ancient systems impedes the direct observation of their tectonic history. However, the basin sedimentary records are more complete, and provide additional insights into the timing and style of the mountain building events. In this study, we employ ~90 1D basin models, ~30 inverse flexural models, isopachs, and paleogeographic maps to better understand the Paleozoic history of North America.

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Request a visit from Kurt W. Rudolph!

American Association of Petroleum Geologists (AAPG)
VG Abstract

The Betic hinterland, in the westernmost Mediterranean, constitutes a unique example of a stack of metamorphic units. Using a three-dimensional model for the crustal structure of the Betics-Rif area this talk will address the role of crustal flow simultaneously to upper-crustal low-angle faulting in the origin and evolution of the topography.

Request a visit from Juan I. Soto!

American Association of Petroleum Geologists (AAPG)

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