Friday, February 04, 2011

How Old do You Want it to be? Radiometric Cherry-Picking

"Naturalistic radiometric agedating is inconsistent because it yields a variety of dates that can be selected based on expectations of age. For a century, secular natural historians have used this to extract dates most favorable to the prevailing theory."

This is the conclusion reached by Carl Froede in his analysis of the ongoing controversy for the age of the Martian meteorite found in Antarctica.

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How old do you want it to be?

Selections from Radiometric Cherry-Picking, by Carl R. Froede Jr.

(These selections by Marko Malyj are of the article published in Creation Matters, a publication of Creation Research Society, Volume 15, Number 6, November/December 2010, to appear at ttp:// Marko's added comments are in italics)

The subjective nature of radiometric age-dating can always yield acceptable agedates for rocks, minerals, and fossils because naturalists can adjust or disqualify them at will. This has recently been demonstrated by tests performed on a volcanic meteorite from Mars that gained wide notoriety in the mid-1990s.

In 1984, a meteorite (ALH84001) was discovered in Antarctica and was overlooked for 10 years before it was determined to be of Martian origin (Kerr, 1996). While unusual in mineral composition and organic content (i.e., polycyclic aromatic hydrocarbons were found in fractures) it sparked an international controversy because of small deposits of carbonate defined by some naturalists as evidence of extraterrestrial life.

So how old do you want it to be?

Door Number One: 4.5 billion years old. That would make it just 100 million years after the planet supposedly formed, making it the oldest rock known from any planet.

According to Wayman (2010), the original radiometric age of ALH84001 was derived from the meteorite’s phosphatic minerals. Naturalistic scientist Richard Kerr (1996) summarizes this original age analysis this way

Radiometric dating shows that ALH84001 congealed from magma to become part of the original Martian crust 4.5 billion years ago, just 100 million years after the planet formed, making it the oldest rock known from any planet. Still early in Martian history, a meteorite impact shattered the rock, leaving fractures where minerals — including the putative traces of life — formed perhaps 3.6 billion years ago. Much later, another impact launched the rock into space. Radioactive nuclei created by deep-space radiation show that it wandered there for 16 million years before blazing through Earth’s atmosphere and crashing into the Antarctic ice cap. It lay buried for 13,000 years until scientists found it on wind-scoured ice in the Allan Hills region of Antarctica.

Door Number Two: 4.1 Billion Years Old. We forgot, the meteorite has to get from Mars to Earth, which supposedly happened 400 millions years later. It's a good thing that we can find an issue with the original dating method.

Unfortunately, such minerals can weather in a manner that alters the isotope ratios, producing spurious age estimates.

Lapen et al. (2010) redated the meteorite using orthopyroxene minerals and the results indicated that the meteorite is 400 million years younger than originally thought.

In their examination of the mineralogy of ALH84001, Lapen and his team (2010) determined that it was derived from the Martian mantle. They believe that the volcanic rock can be linked to long-lived volcanic areas such as Tharsus and Elysium which have been active on Mars for the past 4.0 billion years.

However, the real question is not the Martian origin of the rock, but how it came to reside on Earth. Scientists have invoked a catastrophic event called the heavy bombardment (Appendix I) to explain the rock’s journey. During the heavy bombardment, the solar system encountered swarms of impactors that cratered the terrestrial planets, satellites, and even asteroids. Using orthopyroxene minerals, Lapen et al. (2010) arrived at an age of 4.091±0.030 billion years, a time thought to be close to an alleged period of heavy bombardment — between 4.25 and 4.10 billion years ago (Frey, 2008; Lillis et al., 2008).

Door Number Three: 150 to 570 Million Years Old. All the other meteorites of similar composition are nowhere near 4.1 Billion Years old. We're not quite sure how to explain why this one is 4.1 Billion, and the others are billions of years younger, so let's not go there...

Interestingly, other Martian volcanic meteorites of similar composition (i.e., Shergottites) range from 150 to 570 million years in age – making ALH84001 the oldest Martian rock of this type found on Earth to date.

"Believed to have come from Mars, with 17 known examples by mid-2002; the type member is the Shergotty meteorite, which fell in India in 1865. They all have exceptionally young crystallization ages of 150-200 Ma. Shock metamorphism probably occurred when the shergottites were blasted off the Martian surface."
 How should creationists view the reliability of radiometric dating?

Creationist studies have identified significant inconsistencies and errors in radiometric age-dates, and the naturalist claims that Earth is very old based on various forms of radiometric dating. Some of these are listed below (A-G).

A) Using the Rubidium–Strontium (87Rb-87Sr) method, Austin (1988, 1992) demonstrated that basaltic rocks from a Pleistocene (less than two million years old) lava flow on top of the Grand Canyon dated older (1.34±0.04 billion years) than the Precambrian Cardenas Basalt (dated at 1.07 billion years) found deep within the canyon.

B) In his examination of igneous rocks from the Grand Canyon, Austin (1994) documented several instances where radiometric ages were inconsistent with the naturalistic framework of Earth history. Rocks stratigraphically positioned above others consistently dated older than the underlying rocks. In this same work, Austin documented that different radiometric age-dating methods provide different age-dates for the same rock (i.e., isochron discordance).

C) Snelling (1995) noted the failure of U-Th-Pb dating method for the Koongarra uranium deposit in the Northern Territory, Australia. Three uraninite grains even yield a 232Th/208Pb “age” of 0 Ma.

D) In 1996, Austin seriously challenged the Potassium–Argon (40K-40Ar) dating method. A porphyritic dacite formed in 1986 at the Mount St. Helens lava dome yielded radiometric age-dates ranging from 350,000 (±50,000) to 2.8 (±600,000) million years. Austin concluded (p. 342): "The primary assumption upon which K-Ar modelage dating is based assumes zero 40Ar in the mineral phases of a rock when it solidifies. This assumption has been shown to be faulty."

This dating method has also been challenged by naturalists for submarine pillow basalts from Kilauea Volcano, Hawaii where the subaqueous volcanic rocks believed to be less than a thousand years old dated between 160,000 and 42.9 million years (Dalrymple and Moore, 1968). This finding has serious implications for oceanic crust dated using the potassium-argon method in defense of Plate Tectonic Theory.

E) Snelling (2000) documented the subjective nature in using the U-Th-Pb dating of zircon grains for igneous rocks found around the world. He stated([. iii): "Clearly, the results of U-Th-Pb mineral dating are highly dependent on the investigator’s interpretations."

F) Snelling (2004) documented discordant radiometric age-dates for the Brahma amphibolite found deep within the Grand Canyon. He stated (p. iii): "The radiometric methods, long touted as irrefutably dating the earth’s rocks as countless millions of years old, have repeatedly failed to provide reliable and meaningful absolute ages for Grand Canyon rock layers."

G) Baumgardner (2005) discovered measurable 14C in diamonds believed by naturalists to be over a billion years in age. He stated (p. 624):

"With a half life of 5,730 years, radiometric 14C would be nearly exhausted in 57,300 years, or ten half lives. Finding 14C in a specimen whose age is clearly beyond acceptable secular dating limits should raise serious questions. While 14C contamination can and does occur, finding it in billion year-old diamonds appears to seriously question the assumptions of this dating method."

Clearly, naturalistic radiometric agedating is inconsistent because it yields a variety of dates that can be selected based on expectations of age. For a century, secular natural historians have used this to extract dates most favorable to the prevailing theory. Different minerals and different methods can all alter the final result. Logically, these demonstrated errors add uncertainty to any reported result. Many of the problems have been shown by research by creationists. Clearly, radiometric dates are orders of magnitude too great (or small) for biblical history, yet the inconsistencies also argue against a consistent inconsistency — that a correction for something like accelerated decay in the past can make dates useful for diluvial studies.

Such work demonstrates that radiometric age-dating is not science as much as it is a means of defending the uniformitarian, geologic column model.

References (selected)

Austin, S.A. 1988. Grand Canyon lava flows: A survey of isotope dating methods. Impact No. 178. Institute for Creation Research, El Cajon, CA.

Austin, S.A. 1992. Excessively old “ages” for Grand Canyon lava flows. Impact No. 224. Institute for Creation Research, El Cajon, CA.

Austin, S.A. (editor). 1994. Grand Canyon: Monument to Catastrophe. Institute for Creation Research, El Cajon, CA.

Baumgardner, J.R. 2005. 14C evidence for a recent global Flood and a young earth, In Vardiman, L., A.A. Snelling, and E.F. Chaffin (editors). Radioisotopes and the Age of the Earth: Results of a Young-Earth Creationist Research Initiative, pp. 587–630. Institute for Creation Research, El Cajon, CA, and Creation Research Society, Chino Valley, AZ.

Dalrymple, G.B. and J.G. Moore. 1968. Argon-40: Excess in submarine pillow basalts from Kilauea Volcano, Hawaii. Science 161:1132–1135.

Frey, H.V. 2008. Ages of very large impact basins on Mars: Implications for the late heavy bombardment in the inner solar system. Geophysical
Research Letters

Kerr, R.A. 1996. Ancient life on Mars? Science 273:864–866.

Lapen, T.J., M. Righter, A.D. Brandon, V. Debaille, B.L. Beard, J.T. Shafer, and A.H. Peslier. 2010. A younger age for ALH84001 and its geochemical link to Shergottite sources in Mars. Science 328:347–351.

Lillis, R.J., H.V. Frey, and M. Manga. 2008. Rapid decrease in Martian crustal magnetization in the Noachian era: Implications for the dynamo and climate of early Mars. Geophysical Research Letters 35:L14203.

Snelling, A.A. 1995. The failure of U-Th-Pb “dating” at Koongarra, Australia. Creation ex Nihilo Technical Journal 9(1):71–92.

Snelling, A.A. 2000. Dubious radiogenic Pb behavior places U-Th-Pb mineral dating in doubt. Impact No. 319. Institute for Creation Research, El Cajon, CA.

Snelling, A.A. 2004. Radioisotope dating of Grand Canyon rocks: Another devastating failure for long-age geology. Impact No. 376. Institute for
Creation Research, El Cajon, CA.

Wayman, E. 2010. Oldest Martian meteorite not quite so old. Earth 55(7):9.

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