Feb. 2001 Vol. 222 No. 2  Exploration

Perry A. Fischer,  Engineering Editor

It’s a great time to be in the geosciences: Discoveries abound

We must be living in what future hindsight will regard as the golden age of the earth sciences. Landmark discoveries are being made every month. A few that caught my attention follow.

Very early continents. Geologist Stephen Mojzsis, a member of the NASA Astrobiology Institute’s team at the University of Colorado, Boulder, has been working in the Jack Hills formation of Western Australia. Separately, so has a team that included geologist William Peck of Colgate University in Hamilton, New York. The two independent teams have found compelling evidence in zircon for the existence of continents and liquid water 4.3 to 4.4 billion years ago (ya).

Zircon is a mineral that forms as small microscopic crystals as molten granite cools. Ideally, as its crystals grow, small amounts of uranium are trapped inside the crystals. The well-known uranium-to-lead half-life serves as a clock that allows the dating of when the crystals formed.

The history of these particular zircons indicates that they "have really been put through the wringer," said Peck. Isotopic evidence (¹⁸O/¹⁶O) points to a source rock that interacted with water. This was followed by re-melting (perhaps by meteorite impact), followed by crystal formation within cooling granite, then weathering, alluvial transport and, finally, incorporation into sedimentary rock.

Both groups published their work in the Jan. 11, 2001, issue of the British journal Nature. For further information, a good starting place on the web is: http://science.nasa.gov/ headlines/y2001/ast17jan_1.htm?list57400.

Ancient life. Mojzsis is the same fellow who announced nearly five years ago that he had discovered evidence for life 3.85 billion ya. The evidence comes from the now-famous Akilia rock from the Isua Greenstone Belt in central West Greenland. This area is host to the oldest marine sedimentary rocks on earth. Minute graphite inclusions in apatite grains within the rock show signs of biological origin, based on carbon-isotope ratios that are characteristic of more recent rocks with clear biological origin.

The Isua banded-iron formation from which the Akilia rock was taken cannot be directly dated via isotope ratios. Fortunately, dykes of gray gneiss had cut across the banded iron formation. Gneiss, which contains zircon – and thus uranium – can be dated.

Although not everyone is convinced, the evidence has been revisited; so far, it has held. The gneiss places a minimum age of 3.85 million years on the Akilia rock; and carbon isotope ratios remain strongly suggestive of organic origin.

Fast magma. The December 7 issue of Nature had a story concerning research on granite from Alexander Cruden of the University of Toronto and colleagues. In short, their research reduces by about a factor of a thousand the time it takes for granitic dikes and intrusions – whether large or small – to emplace. Granite’s lower viscosity was responsible for its emplacement over thousands, not millions, of years.

Put it all together. Results of the above three findings – assuming they hold – are that Earth had at least a partially solid crust remarkably soon after it formed, which was about 4.6 billion ya; that silica-rich granitic plutons rose relatively fast; that crustal rocks were in contact with liquid water, perhaps even oceans; and that all of the ingredients for life were in place at a very early stage. Perhaps too early.

Evidence of the early emergence of life appears to overlap the well-known period of intense meteorite bombardment that the inner solar system underwent about 3.8 to 4.1 billion ya. This raises the possibility that life arose more than once, only to be wiped out or greatly reduced by cataclysm, as well as the possibility that life itself was delivered here by extremophiles hitchhiking within such meteorites.

Ever-larger clusters. We all know that, unlike most businesses, seismic processing will never have enough computing power. One cost-effective solution being adopted by many companies is cluster computing. It has been advancing rapidly, driven by need combined with ever-cheaper CPUs. Last fall, Conoco claimed the distinction of having the most powerful (0.5 teraflops – trillions of floating point operations per second) Intel-based computer in the petroleum industry. Nowadays, such fame is short lived.

Spectrum Energy and Information Technology, a Houston-based seismic contractor and data processor, says it has built a cluster with 1,200 CPUs that easily trumps Conoco’s machine. Spectrum says its cluster can process at a blinding 0.96 teraflops. The company believes it is the fastest computer in Texas, and the 17th most powerful computer in the world. The company will use its NT/Linux proprietary software to run Kirchhoff prestack depth migrations for its clients.

To keep track of such superlatives, go to www.top500.org. There you will find a list of the 500 fastest computers in the world.

Veritas DGC buys RC². Veritas believes that the technology, people and worldwide experience of RC² are a great fit with the integrated seismic data interpretation and analysis provided by Veritas Exploration Services business unit, according to Dave Robson, chairman and CEO of Veritas. Veritas Exploration Services offers interpretation, visualization and analysis techniques to assist clients in their exploration and reservoir management efforts.

"We will benefit from the complementary technologies and global reach Veritas provides in seismic acquisition, processing, and data library," said William Bashore, RC²’s president.

Under the terms of the agreement, valued at roughly $33 million, Veritas will acquire 100% of RC² in exchange for about 1,137,500 Veritas shares. Closing, subject to certain conditions, should occur in early February.

Comments? Write: fischerp@gulfpub.com