Researchers turn to 3-D technology to examine the formation of cliffband landscapes

This is a scene from the Colorado Plateau region of Utah. -  Dylan Ward
This is a scene from the Colorado Plateau region of Utah. – Dylan Ward

A blend of photos and technology takes a new twist on studying cliff landscapes and how they were formed. Dylan Ward, a University of Cincinnati assistant professor of geology, will present a case study on this unique technology application at The Geological Society of America’s Annual Meeting & Exposition. The meeting takes place Oct. 19-22, in Vancouver.

Ward is using a method called Structure-From-Motion Photogrammetry – computational photo image processing techniques – to study the formation of cliff landscapes in Colorado and Utah and to understand how the layered rock formations in the cliffs are affected by erosion.

To get an idea of these cliff formations, think of one of the nation’s most spectacular tourist attractions, the Grand Canyon.

“The Colorado plateau, for example, has areas with a very simple, sandstone-over-shale layered stratigraphy. We’re examining how the debris and sediment off that sandstone ends up down in the stream channels on the shale, and affects the erosion by those streams,” explains Ward. “The river cuts down through the rock, creating the cliffs. The cliffs walk back by erosion, so there’s this spectacular staircase of stratigraphy that owes its existence and form to that general process.”

Ward’s research takes a new approach to documenting the topography in very high resolution, using a new method of photogrammetry – measurement in 3-D, based on stereo photographs.

“First, we use a digital camera to take photos of the landscape from different angles. Then, we use a sophisticated imaging processing program than can take that set of photos and find the common points between the photographs. From there, we can build a 3-D computer model of that landscape. Months of fieldwork, in comparison, would only produce a fraction of the data that we produce in the computer model,” says Ward.

Ward says that ultimately, examining this piece of the puzzle will give researchers an idea as to how the broader U.S. landscape was formed.

The causes and consequences of global climate warming that took place 56 million years ago studied

This image shows continental sediments in the Esplugafreda ravine, a small tributary of the Noguera Ribagorzana river, in the extreme west of the province of Lleida and close to the village of Aren (Huesca). -  UPV/EHU-University of the Basque Country
This image shows continental sediments in the Esplugafreda ravine, a small tributary of the Noguera Ribagorzana river, in the extreme west of the province of Lleida and close to the village of Aren (Huesca). – UPV/EHU-University of the Basque Country

The growing and justified concern about the current global warming process has kindled the interest of the scientific community in geological records as an archive of crucial information to understand the physical and ecological effects of ancient climate changes. A study by the UPV/EHU’s Palaeogene Study Group deals with the behaviour of the sea level during the Palaeocene-Eocene Thermal Maximum (PETM) 56 million years ago and has ruled out any connection. The study has been published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

“The fall in sea level did not unleash the emission of greenhouse gases during the Palaeocene-Eocene Thermal Maximum (PETM),” pointed out Victoriano Pujalte, lecturer in the UPV/EHU’s Department of Stratigraphy and Palaeontology, and lead researcher of the study.

The Palaeocene-Eocene Thermal Maximum (PETM) was a brief interval (in geological terms, it “only” lasted about 200,000 years) of extremely high temperatures that took place 56 million years ago as a result of a massive emission of greenhouse gases into the atmosphere. The global temperature increase is reckoned to have been between 5º C and 9º C. It was recorded in geological successions worldwide and was responsible for a great ecological impact: the most striking from an anthropological point of view was its impact on mammals, but it also affected other organisms, including foraminifera and nannofossils (marine microorganisms that are at the base of the trophic chain) and plants.

However, what actually caused this warming remains a controversial issue. The most widely accepted hypothesis suggests that it was due to the destabilising of methane hydrates that remained frozen on ocean floors. “Some authors, like Higgins and Schrag (2006), for example, proposed that a fall in sea level could have caused or co-contributed towards the unleashing of the emission of methane or CO2,” pointed out Victoriano Pujalte, lecturer in the UPV/EHU’s Department of Stratigraphy and Palaeontology, and lead researcher in the study. According to this hypothesis, “the marine sediments that were submerged in the sea were exposed when the sea level fell, and were responsible for the CO2 emissions,” he added. That is what, to a certain extent, prompted this study. Others not only reject that possibility but also the fall in sea level itself. “We set out to try and establish the behaviour of the sea level during that time interval, the PETM,” said Pujalte.

There is no cause-effect relationship

The studies were carried out mainly in the Pyrenees between Huesca and Lérida, specifically in the Tremp-Graus Basin, and also in Zumaia (Gipuzkoa, Basque Country). The Palaeocene-Eocene rocks have outcropped extensively in both areas, in other words, exposed on the surface, and they represent a whole range of ancient atmospheres, both continental and marine. “They provide a unique opportunity to explore the effects of changes in sea level and to analyse their effects,” added Pujalte.

The most useful indicators are the stable oxygen and carbon isotopes. The oxygen ones provide information on palaeotemperatures, but any sign of them can only be retrieved in deep-sea sample cores. The carbon isotopes provide data on variations in CO2 content in the atmosphere and in the oceans, and they can also be retrieved in ancient rocks that have outcropped in above-ground plots of land. In general, the variations of both isotopes run parallel, given that an increase in the proportion of CO2 is coupled with an increase in temperature.

The results obtained indicate that the PETM was in fact preceded by a fall in sea level, the size of which is estimated to have been about 20 metres and the maximum descent of which probably occurred about 75 million years before the start of the PETM. “However, it is doubtful that the descent was the cause of the PETM, although it could have contributed towards it,” pointed out Victoriano Pujalte. “They occurred at the same time, but there is no cause-effect relationship.”

Furthermore, the researchers observed that the rise in the sea level continued after the PETM, when the global temperature returned to normal levels. “Its origin was not only caused, therefore, by the thermal expansion of the oceans linked to the warming,” said Pujalte. “It is suggested that the most likely cause of it was the volcanic activity documented in the North Sea during the end of the Palaeocene and start of the Eocene; this activity was related to the expansion of the oceanic ridge in the North Atlantic,” he concluded.

A stepping-stone for oxygen on Earth

For most terrestrial life on Earth, oxygen is necessary for survival. But the planet’s atmosphere did not always contain this life-sustaining substance, and one of science’s greatest mysteries is how and when oxygenic photosynthesis-the process responsible for producing oxygen on Earth through the splitting of water molecules-first began. Now, a team led by geobiologists at the California Institute of Technology (Caltech) has found evidence of a precursor photosystem involving manganese that predates cyanobacteria, the first group of organisms to release oxygen into the environment via photosynthesis.

The findings, outlined in the June 24 early edition of the Proceedings of the National Academy of Sciences (PNAS), strongly support the idea that manganese oxidation-which, despite the name, is a chemical reaction that does not have to involve oxygen-provided an evolutionary stepping-stone for the development of water-oxidizing photosynthesis in cyanobacteria.

“Water-oxidizing or water-splitting photosynthesis was invented by cyanobacteria approximately 2.4 billion years ago and then borrowed by other groups of organisms thereafter,” explains Woodward Fischer, assistant professor of geobiology at Caltech and a coauthor of the study. “Algae borrowed this photosynthetic system from cyanobacteria, and plants are just a group of algae that took photosynthesis on land, so we think with this finding we’re looking at the inception of the molecular machinery that would give rise to oxygen.”

Photosynthesis is the process by which energy from the sun is used by plants and other organisms to split water and carbon dioxide molecules to make carbohydrates and oxygen. Manganese is required for water splitting to work, so when scientists began to wonder what evolutionary steps may have led up to an oxygenated atmosphere on Earth, they started to look for evidence of manganese-oxidizing photosynthesis prior to cyanobacteria. Since oxidation simply involves the transfer of electrons to increase the charge on an atom-and this can be accomplished using light or O2-it could have occurred before the rise of oxygen on this planet.

“Manganese plays an essential role in modern biological water splitting as a necessary catalyst in the process, so manganese-oxidizing photosynthesis makes sense as a potential transitional photosystem,” says Jena Johnson, a graduate student in Fischer’s laboratory at Caltech and lead author of the study.

To test the hypothesis that manganese-based photosynthesis occurred prior to the evolution of oxygenic cyanobacteria, the researchers examined drill cores (newly obtained by the Agouron Institute) from 2.415 billion-year-old South African marine sedimentary rocks with large deposits of manganese.

Manganese is soluble in seawater. Indeed, if there are no strong oxidants around to accept electrons from the manganese, it will remain aqueous, Fischer explains, but the second it is oxidized, or loses electrons, manganese precipitates, forming a solid that can become concentrated within seafloor sediments.

“Just the observation of these large enrichments-16 percent manganese in some samples-provided a strong implication that the manganese had been oxidized, but this required confirmation,” he says.

To prove that the manganese was originally part of the South African rock and not deposited there later by hydrothermal fluids or some other phenomena, Johnson and colleagues developed and employed techniques that allowed the team to assess the abundance and oxidation state of manganese-bearing minerals at a very tiny scale of 2 microns.

“And it’s warranted-these rocks are complicated at a micron scale!” Fischer says. “And yet, the rocks occupy hundreds of meters of stratigraphy across hundreds of square kilometers of ocean basin, so you need to be able to work between many scales-very detailed ones, but also across the whole deposit to understand the ancient environmental processes at work.”

Using these multiscale approaches, Johnson and colleagues demonstrated that the manganese was original to the rocks and first deposited in sediments as manganese oxides, and that manganese oxidation occurred over a broad swath of the ancient marine basin during the entire timescale captured by the drill cores.

“It’s really amazing to be able to use X-ray techniques to look back into the rock record and use the chemical observations on the microscale to shed light on some of the fundamental processes and mechanisms that occurred billions of years ago,” says Samuel Webb, coauthor on the paper and beam line scientist at the SLAC National Accelerator Laboratory at Stanford University, where many of the study’s experiments took place. “Questions regarding the evolution of the photosynthetic pathway and the subsequent rise of oxygen in the atmosphere are critical for understanding not only the history of our own planet, but also the basics of how biology has perfected the process of photosynthesis.”

Once the team confirmed that the manganese had been deposited as an oxide phase when the rock was first forming, they checked to see if these manganese oxides were actually formed before water-splitting photosynthesis or if they formed after as a result of reactions with oxygen. They used two different techniques to check whether oxygen was present. It was not-proving that water-splitting photosynthesis had not yet evolved at that point in time. The manganese in the deposits had indeed been oxidized and deposited before the appearance of water-splitting cyanobacteria. This implies, the researchers say, that manganese-oxidizing photosynthesis was a stepping-stone for oxygen-producing, water-splitting photosynthesis.

“I think that there will be a number of additional experiments that people will now attempt to try and reverse engineer a manganese photosynthetic photosystem or cell,” Fischer says. “Once you know that this happened, it all of a sudden gives you reason to take more seriously an experimental program aimed at asking, ‘Can we make a photosystem that’s able to oxidize manganese but doesn’t then go on to split water? How does it behave, and what is its chemistry?’ Even though we know what modern water splitting is and what it looks like, we still don’t know exactly how it works. There is a still a major discovery to be made to find out exactly how the catalysis works, and now knowing where this machinery comes from may open new perspectives into its function-an understanding that could help target technologies for energy production from artificial photosynthesis. ”

Next up in Fischer’s lab, Johnson plans to work with others to try and mutate a cyanobacteria to “go backwards” and perform manganese-oxidizing photosynthesis. The team also plans to investigate a set of rocks from western Australia that are similar in age to the samples used in the current study and may also contain beds of manganese. If their current study results are truly an indication of manganese-oxidizing photosynthesis, they say, there should be evidence of the same processes in other parts of the world.

“Oxygen is the backdrop on which this story is playing out on, but really, this is a tale of the evolution of this very intense metabolism that happened once-an evolutionary singularity that transformed the planet,” Fischer says. “We’ve provided insight into how the evolution of one of these remarkable molecular machines led up to the oxidation of our planet’s atmosphere, and now we’re going to follow up on all angles of our findings.”

Volcanoes like you’ve never seen them before

The Geological Society of America's new Special Paper 464, 'Stratigraphy and Geology of Volcanic Areas,' edited by Gianluca Groppelli and Lothar Viereck-Goette conveys state-of-the-art methodologies for mapping volcanic areas and highlights recent studies on the stratigraphy, structure, and evolution of both active and extinct volcanic terrains. -  The Geological Society of America
The Geological Society of America’s new Special Paper 464, ‘Stratigraphy and Geology of Volcanic Areas,’ edited by Gianluca Groppelli and Lothar Viereck-Goette conveys state-of-the-art methodologies for mapping volcanic areas and highlights recent studies on the stratigraphy, structure, and evolution of both active and extinct volcanic terrains. – The Geological Society of America

Stratigraphy and Geology of Volcanic Areas conveys state-of-the-art methodologies for mapping volcanic areas and highlights recent studies on the stratigraphy, structure, and evolution of both active and extinct volcanic terrains. The 14 chapters in this new Special Paper from The Geological Society of America, as well as the accompanying CD-ROM, present innovations in geological and hazard mapping of volcanic terrains with the goal of explaining field survey methods and their translation into geological maps.

According to the book’s editors, Gianluca Groppelli (Instituto per la Dinamica dei Processsi Ambientali-Sezione di Milano) and Lothar Viereck-Goette (Institut für Geowissenschaften, Friedrich-Schiller-Universität Jena), “All of the papers [in this volume] confirm the geological map as the basic document for further and more detailed studies,” call the geological map “the warehouse in which to store data on past eruptions and intereruption phenomena with significant implications for volcanic hazard assessment,” as well as other volcanological features.

The volume editors “hope that this book will be used for further discussions and analysis to help establish a common world methodology for mapping volcanic areas.”

Sites visited, mapped on CD-ROM, and detailed in this Special Paper include the Aeolian Archipelago, Italy; Stromboli volcano, Italy; the volcanic island of Ustica, Italy; Vulsini Volcanoes, central Italy; the Central Anatolian volcanic province, Turkey; Tenerife, Canary Islands; Terceira Island, Azores; Campi Flegrei, Bay of Naples, Italy; Procida Island, Italy; Ischia caldera, Italy; Mount Etna, Greece; the Colima volcanic complex, Mexico; and Arequipa, Peru.

Paleozoic ‘sediment curve’ provides new tool for tracking sea-floor sediment movements

Follows sea-level rise and fall between 542 and 251 million years ago

As the world looks for more energy, the oil industry will need more refined tools for discoveries in places where searches have never before taken place, geologists say.

One such tool is a new sediment curve (which shows where sediment-on-the-move is deposited), derived from sediments of the Paleozoic Era 542 to 251 million years ago, scientists report in this week’s issue of the journal Science. The sediment curve covers the entire Paleozoic Era.

“The new Paleozoic sea-level sediment curve provides a way of deriving predictive models of sediment migration on continental margins and in interior seaways,” said Bilal Haq, lead author of the Science paper and a marine geologist at the National Science Foundation (NSF). The paper’s co-author is geologist Stephen Schutter of Murphy Oil International in Houston, Tx.

“The sediment curve is of interest to industry, and also to scientists in academia,” said Haq, “as the rise and fall of sea-level form the basis for intepretations of Earth history based on stratigraphy.”

Through stratigraphy, the study of rock layering (stratification), scientists can derive a sequence of time and events in a particular region. Recent advances in the field of stratigraphy, including better time-scales for when sediments were deposited, and availability of data on a worldwide basis, are allowing scientists to reconstruct sea level during the Paleozoic.

The rises and falls of sea level during this period form the basis of stratigraphic interpretations of geology not only in the sea, but on land. These sea level increases and decreases are used extensively, Haq said, in predictive models of sediment movements.

The current Science paper is a shorter version of the results of a global synthesis of Paleozoic stratigraphy on which the authors have worked for many years.

“We hope that the publication of a sediment curve for this entire era will enhance interest in Paleozoic geology,” said Haq, “and help the exploration industry in its efforts to look at older and deeper sediments.”