Welcome to Core Elements #123!

Classes in colleges and universities started last month. One of the things I most enjoy every year is meeting new students and sharing geoscience knowledge and skill sets, as well as the “pleasure of finding things out” (to paraphrase Richard Feynman’s fabulous book) with them.

Now, let’s jump into some geoscience research and news!

Rasoul Sorkhabi

Editor, Core Elements

Most Prolific Authors in AAPG Bulletin

AAPG Bulletin is in its 110th year. Who are the most published authors in the Bulletin? Here are the results of my survey from 1917–2025. 

No. 1: Scott L. Montgomery: 52 articles from 1996–2005

Montgomery (born 1951) was commissioned to write monthly articles in the series “E&P Notes” for the Bulletin.

No. 2: Frederic H. Lahee: 40 articles from 1922–1958

Lahee (1884–1968) was a founding member of AAPG. He taught at MIT from 1912 to 1918, then worked for Sun Oil in Dallas until he retired in 1947. He wrote the annual “Wildcat Drilling and Exploratory Drilling” reports for the Bulletin from 1937 to 1955.

No. 3: Horace G. Richards: 36 articles from 1945–1975

Richards (1906–1984), a paleontologist, wrote the annual “Developments in Atlantic Coastal Plains Between New Jersey and South Carolina” for the Bulletin from 1946 to 1970.

No. 4: M. Dane Picard: 32 articles from 1955–1995

Picard (1927–2021) was a professor of sedimentology and petroleum geology at the University of Utah from 1968 until his death. (As I work for the University of Utah, I’m very proud to see his name on this list.)

No. 5: Gerald L. Carpenter: 32 articles from 1957–1987

Carpenter (1924–2012) was a petroleum geologist at the Indiana Geological Survey and a dedicated AAPG member for 57 years. He wrote “Developments in Indiana and East-Central States” reports for the Bulletin from 1956 to 1987.

No. 6: Paul Weimer: 30 articles from 1990–2022

Weimer (born 1956) retired from the University of Colorado in 2024 after serving as a professor for 34 years. He was AAPG President (2011–2012) and was awarded the AAPG Sidney Powers Medal in 2020.

No. 7: Fang Hao: 30 articles from 1998–2025

Hao Fang (born 1964) is a professor at China University of Petroleum and a member of the Chinese Academy of Sciences.

No. 8: Arville Irving Levorsen: 29 articles from 1927–1966

Levorsen (1894–1965) was a Stanford professor and author of the influential textbook Geology of Petroleum, first published in 1954.

No. 9: Michel T. Halbouty: 28 articles from 1935–1999

Halbouty (1909–2004) was a Texan and a legend in oil field discovery. He was AAPG President in 1966. AAPG awards the Michel T. Halbouty Outstanding Leadership Award annually in his honor.

No. 10: Donald C. Barton: 28 articles from 1921–1941

Barton (1889–1939) was a Harvard graduate who worked for Humble Oil. He was one of the founders of the Society of Exploration Geophysicists and served as SEG’s first president (1931–1933) and AAPG President (1938–1939).

Publish your work in AAPG Bulletin: Do you have some research to publish? Consider publishing in AAPG Bulletin. You can learn more about why publishing in AAPG Bulletin is important in my recent Explorer article.

Quaternary Sequence Stratigraphy

Application of Quaternary Sequence Stratigraphy (AAPG Bulletin, 2026)

In the September issue of AAPG Bulletin, Alessandro Amorosi published an interesting paper on Quaternary sequence stratigraphy.

What is sequence stratigraphy?

Sequence stratigraphy in petroleum geoscience combines seismic interpretation with sedimentologic and stratigraphic data to better understand:

• Basin infill sequences
• Depositional environments and facies
• Unconformity surfaces
• Regression and transgression cycles
• Sea-level changes
• Basin subsidence history
• Major source-reservoir-cap rock deposition
• Paleogeographic mapping

Field history:

• Lawrence Sloss (1913–1996), at Northwestern University in Illinois, suggested initial concepts in sequence stratigraphy in the 1960s.
• Three of Sloss’s students—Peter Vail, Robert Mitchum, and John Sangree—worked for Exxon in the 1970s. They developed sequence/seismic stratigraphy methods and applied them to petroleum exploration.
• In 1977, AAPG Memoir 26 was published, a benchmark volume on Seismic Stratigraphy: Applications to Hydrocarbon Exploration.
• AAPG followed it with Seismic Stratigraphy II (Memoir 39, 1985) and Atlas of Seismic Stratigraphy, 3 volumes (AAPG Studies in Geology 27, 1987–1989, edited by Albert W. Bally).

Amorosi describes the following data advantages for the Quaternary record:

• Excellent age control
• High-resolution data on climate and sea-level changes
• Well-preserved stratigraphy
• Direct observations of sediment fluxes and depositional processes
• Robust paleo-ecological framework and fossil assemblages
• Limited diagenetic overprint

Amorosi cautions that:

• Quaternary eustatic changes are much higher than those of earlier geological periods.
• This should be taken into account when using the Quaternary record to interpret the geological past.

Why it matters:

• Quaternary sequence stratigraphy offers an important framework to interpret the ancient sedimentary record in terms of quantified modern processes.
• Besides petroleum exploration, Quaternary sequence stratigraphy is also applicable to groundwater mapping, seismic-hazard assessment, infrastructure development, and contaminant flow paths.

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In Memory of Sedimentologist Roger Walker (1939–2026)

Roger Walker was best known for his publication Facies Models

On August 14, Dr. Roger G. Walker passed away.

Jhonny Casas, a former member of the AAPG Advisory Council, has published a memorial for Walker in Episodes.

A look at Walker’s life:

• Walker obtained his PhD from Oxford University in 1964. He was awarded a postdoctoral fellowship at Johns Hopkins University to work with the legendary sedimentologist Francis Pettijohn.
• He joined McMaster University in Canada in 1998, and, over the next 32 years, he supervised 34 M.S. and 15 PhD students (including Jhonny Casas) as well as five postdoctoral fellows.
• After that, he began a consultancy career in Calgary for oil and gas companies.
• His book Facies Models (1979, 1984, 1992) has trained generations of sedimentologists and petroleum geologists.
• Walker published several papers in AAPG Bulletin, including one in 1985 on the Alberta Basin.

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