General

Long-standing farming practices in California’s Sacramento-San Joaquin River Delta expose fragile peat soils to wind, rain and cultivation, emit carbon dioxide (CO2) and cause land subsidence.

To capture or contain the carbon, farmers would “grow” wetlands. In doing so, they would begin to rebuild the Delta’s unique peat soils, take CO2 out of the atmosphere, ease pressure on the Delta’s aging levees, and infuse the region with new economic potential.

We learn more from USGS bio-geochemist Robin Miller about how this could help California, the nation, and the world.

[Via USGS Corecast]

Geothermal power production could significantly add to the electric power generating capacity in the United States. 

The U.S. Geological Survey assessment released today is the first national geothermal resource estimate in more than 30 years.

The results of this assessment show that the United States has an estimated 9,057 Megawatts-electric (MWe) of power generation potential from domestic, conventional, identified geothermal systems, 30,033 MWe of power generation potential from conventional, undiscovered geothermal resources, and 517,800 MWe of power generation potential from unconventional (high temperature, low permeability) Enhanced Geothermal Systems (EGS) resources. 

The results of this assessment indicate that full development of the conventional, identified systems alone could expand geothermal power production by approximately 6,500 MWe, or about 260% of the currently installed geothermal total of more than 2500 MWe.  The resource estimate for unconventional EGS is more than an order of magnitude larger than the combined estimates for both identified and undiscovered conventional geothermal resources and, if successfully developed, could provide an installed geothermal electric power generation capacity equivalent to about half of the currently installed electric power generating capacity in the United States.

“The results of this assessment point to a greater potential for geothermal power production than previous assessments,” said Dirk Kempthorne, U.S. Secretary of the Interior. “Geothermal energy is not only a renewable resource, but could significantly contribute to our domestic energy resource base.”

Results of this USGS assessment indicate that the power generation potential from identified geothermal systems range from 3,675 MWe (95% probability) to 16,457 MWe (5% probability); the power generation potential from undiscovered geothermal systems range from 7,917 MWe (95% probability) to 73,286 MWe (5% probability); and the power generation potential from Enhanced Geothermal Systems range from 345,100 MWe (95% probability) to 727,900 MWe (5% probability).

Geothermal energy is an extremely important but underutilized domestic, renewable energy resource.  The nearly 15,000 Gigawatt-hours of geothermal power generated in 2005 constituted 25% of domestic nonhydroelectric renewable electric power generation (a little over 4,055,400 total Gigawatt-hours of electricity were produced in the United States in 2005). 

The USGS assessment evaluated 241 identified moderate-temperature (90 to 150^oC; 194 to 302^oF) and high-temperature (greater than 150^oC) geothermal systems located on private and public lands.  Geothermal systems located on public lands closed to development, such as national parks, were not included in this assessment.  Electric-power generation potential was also determined for several low-temperature (less than 90^oC) systems in Alaska for which local conditions make electric power generation feasible.  The assessment also included a provisional estimate of the power generation potential from the application of unconventional, EGS technology.

This assessment benefited from cooperation with the Department of Energy, Bureau of Land Management, the University of Nevada - Reno, the University of Utah, Idaho National Laboratory, Lawrence Berkeley National Laboratory, state and local agencies, and the geothermal industry.

To learn more about USGS National Geothermal Resource efforts and to see results of the assessment, please visit the Energy Resources Web site.

[Via USGS]

I stumbled across this on Universe Today’s “Where in The Universe Challenge” and thought it made a very interesting geologic phenomenon to write about. (Apologies to Ron and the gang for potentially stealing an idea from the Where on Google Earth challenge.)

Source: Google Earth

What does the above photograph look like on your first impression? I immediately said an impact crater and was amazed at how well defined this was. Especially when you find out this feature has a diameter of 30 kilometers!

This interesting feature is known as the Richat Structure and is located in the African country of Mauritania. Below is an embedded Google Maps frame showing the location.

View Larger Map

This structure is so big, that while zooming in to Mauritania on Google Maps, I was immediately able to see it on a rather zoomed out view.

Anyway, what exactly is this structure? It was originally thought to have been an impact crater when it was first seen on a large scale by scientists. More research eventually revealed that it was not actually an impact crater, but instead a a circular anticline whose crest has been eroded away.

Kim from All of My Faults Are Stress Related adds this comment after reading a paper linked in the Wikipedia article on the structure:

It’s not just a circular anticline - it’s a dome above a Cretaceous pluton. (The article describes the intrusion as a plug, but I wonder if we’re not looking at the top of a laccolith - like the Henry Mountains in Utah, but not eroded through to the pluton itself.)

The paper is titled “Resolving the Richat enigma: Doming and hydrothermal karstification above an alkaline complex,” by Matton G, Jébrak M, Lee JK:

The Richat structure (Sahara, Mauritania) appears as a large dome at least 40 km in diameter within a Late Proterozoic to Ordovician sequence. Erosion has created circular cuestas represented by three nested rings dipping outward from the structure. The center of the structure consists of a limestone-dolomite shelf that encloses a kilometer-scale siliceous breccia and is intruded by basaltic ring dikes, kimberlitic intrusions, and alkaline volcanic rocks. Several hypotheses have been presented to explain the spectacular Richat structure and breccia, but their origin remains enigmatic. The breccia body is lenticular in shape and irregularly thins at its extremities to only a few meters. The breccia was created during karst dissolution and collapse. Internal sediments fill the centimeter- to meter-scale cavities. Alkaline enrichment and the presence of Cretaceous automorphous neoformed K-feldspar demonstrate the hydrothermal origin of these internal sediments and their contemporaneity with magmatism. A model is proposed in which doming and the production of hydrothermal fluids were instrumental in creating a favorable setting for dissolution. The circular Richat structure and its breccia core thus represent the superficial expression of a Cretaceous alkaline complex with an exceptionally well preserved hydrothermal karst infilling at its summit.

For readers not familiar with anticlines, below is a cross section of an anticline to help visualize what might be going on.

Source: Wikipedia - Anticline

According to the website Google Sightseeing, there are a few other similar looking features that can be found in Africa: The Jebel Uwaynat that borders Sudan, Egypt and Libya and the Brandberg Intrusion in Namibia.

[Via Universe Today]

More Information

• Dark Roasted Blend - The Richat Structure, Eye of the Earth
• Universe Today - Where in The Universe Challenge #22
• Wikipedia - Richat Structure

The last week in September is known as Sea Otter Awareness Week throughout California. To bring more attention to the issues surrounding the sea otter and its ongoing recovery from near extinction, we interviewed Tim Tinker, USGS lead sea-otter researcher. Video also provided in the Transcript/Links section.

[Via USGS Corecast]

The last week in September is known as Sea Otter Awareness Week throughout California. To bring more attention to the issues surrounding the sea otter and its ongoing recovery from near extinction, we interviewed Tim Tinker, USGS lead sea-otter researcher. Video also provided in the Transcript/Links section.

[Via USGS Corecast]