Whole-Rock K-Ar Model and Isochron, and Rb-Sr, Sm-Nd, and Pb-Pb Isochron, "Dating" of the Somerset Dam Layered Mafic Intrusion, Australia | The Institute for Creation Research
 
Whole-Rock K-Ar Model and Isochron, and Rb-Sr, Sm-Nd, and Pb-Pb Isochron, "Dating" of the Somerset Dam Layered Mafic Intrusion, Australia

Download PDFDownload Whole-Rock K-Ar Model and Isochron, and Rb-Sr, Sm-Nd, and Pb-Pb Isochron, "Dating" of the Somerset Dam Layered Mafic Intrusion, Australia PDF

Presented at the Fifth International Conference on Creationism, Pittsburgh, Pennsylvania, August 4–9, 2003. Published in: Proceedings of the Fifth International Conference on Creationism, R. L. Ivey (Eds.), pp. 305–324, 2003.

© 2003 Creation Science Fellowship, Inc., Pittsburgh, PA, USA. Published with permission. All rights reserved.

Abstract

The Somerset Dam layered mafic intrusion in southeast Queensland, Australia, has been conventionally dated as Late Triassic by the apparently successful application of radioisotopic dating techniques. Mineralogical, geochemical, and isotopic evidence indicates that all of this gabbro intrusion’s cyclic units were derived coevally from the same parental basaltic magma, with an initial homogeneous
isotopic mixture ideal for yielding concordant isochron ages. However, newly obtained K-Ar, Rb-Sr, Sm-Nd, and Pb-Pb radioisotopic data from 15 whole-rock samples (representing all gabbro macrolayers in four of the intrusion’s cyclic units) yield discordant isochron “ages,” although the excellent-fitting 15-point K-Ar isochron suggests the resultant 174±8 Ma “age” (Middle Jurassic) should be regarded as the revised conventional age of the layered intrusion. Nevertheless, it is concluded that these discordances between the radioisotope systems are likely due to changes in their decay rates in the past, with the longer half-life β-emitter 87Rb being accelerated more and thus yielding an older “age.” Furthermore, the Sr, Nd, and Pb isotopes indicate the parental basaltic magma was derived from a depleted mantle source, while the large spread of Nd TDM “ages” suggests accelerated radioisotopic decay rates during the partial melting and magma ascent. It is concluded that the Somerset Dam layered mafic intrusion has inherited the radioisotopic signature of its mantle source, and so the conventional radioisotopic dating techniques do not provide its true age.

Keywords

Gabbro, Layered Intrusion, Australia, Potassium-Argon, Rubidium-Strontium, Samarium-Neodymium, Lead-Lead, Radioisotopic Dating, Whole-Rock Model “Ages,” Whole-Rock Isochron “Ages,” Discordances, Decay “Constants,” Accelerated Decay, Mantle Source Inheritance

For Full Text

Please see the Download PDF link above for the entire article.

The Latest
NEWS
Indian Kangaroo Pictographs Challenge Evolution
by Brian Thomas, Ph.D., and Timothy Clarey, Ph.D. Evolutionary narratives insist that kangaroos, and the marsupials they represent, evolved millions...

NEWS
Hacked Genome Damages Cell, Declares Creator's Genius
Researchers have just reported a newly recoded bacterial genome in which genetic optimization was markedly reduced.1 Optimization is a principle...

NEWS
Monkey Fossil Reveals Diversity and Flood Boundary
Old World monkey and ape fossils both appear suddenly in the fossil record. (Note: “Old World” refers to countries known to Europeans before...

NEWS
Moon Is Unexpectedly Still Cooling and Shrinking
Scientists have concluded that our moon is probably still in the process of slightly shrinking as it cools.1,2 Photographs from the...

NEWS
Inside June 2019 Acts & Facts
How can we resolve the conflicting message of a good creation with the evil that surrounds us? How does geological research uncover Earth’s youth?...