If you’ve never had a close-up encounter with a deepwater turbidite, perhaps it’s time.
In fact, you may be surprised at the ready accessibility of some really fine outcrops of these type of rocks.
They’re in northeastern Mexico, just a quick hop from Houston via plane, followed by a four-hour drive that traverses about 150 miles.
Yes, it’s slow going on not-so-good roads, but look at it this way: At 35 mph, you can kick back and enjoy the scenery -- and the final destination is rewarding indeed.
“Many companies are interested in the outcrops, which show spectacular slumping and debrites (debris flows) in thin-bedded turbidite sequences,” said consulting geologist Steve Cossey, an AAPG member who specializes in deepwater sediments. “In fact, the best outcrops in that area of Mexico are mainly slumped, thin-bedded turbidites.”
Why does this matter?
One reason is that the Paleocene-Eocene Chicontepec formation exposed in the road cuts is partially equivalent to the deepwater Wilcox exploration going on in the Gulf of Mexico, according to Cossey. He noted the Chicontepec holds some of Mexico’s largest oil reserves -- perhaps as much as 12 billion barrels -- and more than 40 fields currently produce from it.
“There are some huge fields located just a three-hour drive south of the outcrops,” Cossey said. “And there are a few wells producing maybe 30 miles away.”
Exposing the Exposures
Cossey, president of Cossey and Associates Inc. in Durango, Colo., first became excited about the outcrop area after seeing some impressive photos of the exposures included in a thesis by Mark Bitter, another AAPG member who worked the area in 1984 while earning his master’s degree at the University of Kansas. One of the thesis outcrop photos graced the cover of the October 1996 AAPG BULLETIN.
During Cossey’s initial trip to this part of Mexico in 2004, he was joined by Bitter, now with Marathon Oil, to scout out the latter’s old field locations.
Today, Cossey leads field trips to the area to accommodate geologists, geophysicists and engineers who are dealing with slumped reservoirs or thin-bedded reservoirs. As many as 16 outcrops are on a typical itinerary.
His most recent field trip in May of this year was undertaken for a Norwegian company and included participants from Houston as well as Norway, an apt testimony to just how far some folks will travel for this experience.
An earlier trip hosted a corporate group from Australia.
To add to the area’s lure, some of the rock exposures are getting a facelift of sorts.
“Some of the best outcrops from Mark’s thesis are somewhat overgrown,” Cossey noted. “After several trips down there and getting to know the locals, I realized that for a reasonable cost I could get a team of ‘campesinos’ (workers who specialize in clearing the highly vegetated countryside) with machetes and other basic equipment to clean and restore the outcrops to their former glory.
“The first step is to get the machetes and chop, and then shovel the debris that’s fallen down the road cut over the years,” Cossey said. “We’ll get the vegetation off first and then see if we can scrape back with shovels and get the surface weathering off the outcrops. Some outcrops are so overgrown it would be years before weed killer would take effect.”
Parking areas will be created near the exposures so trip participants can avoid the potential hazards of standing in the road.
The project is moving swiftly, with one outcrop already rejuvenated and another about one-half completed as of the end of May. Several other roadside outcrops have been identified for “restoration” and will be worked on in the coming months.
Fringe Benefits
It is noteworthy that the effort overall is about more than geology per se.
The focus area is a relatively poor locale, which is off the beaten path southwest of Tampico. It’s a mix of Mexican and Indian culture and home to the Huasteca Indians, many of whom speak only their native Náhuatl language.
Cossey envisions that sprucing up the outcrops might be a way to promote geo-tourism in combination with the cultural experience of the Huasteca Indians. Visiting groups of geologists would provide valuable tourist income to help the local economy.
The local leaders clearly are pleased already.
The mayor of the town of Atlapexco, Ing. Joel Nochebuena Hernández, turned out with other dignitaries for a ceremony at the one already-completed outcrop. Cossey and his assistant, Juan Ampacun Robledo from the Tampico Tourist Board, handed out certificates of appreciation to the mayor, assistant mayor and other officials whose approval was key to implementing a project of this kind in rural Mexico.
Following the event, a Huasteca regional newspaper included an article about the project and the ceremony.