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
After 30 Years, Red Kites Soar in British Skies
Good news is always welcome. So, it’s good to learn of another conservation comeback. This time it’s the red kite happily soaring in Great...

CREATION PODCAST
Meet Dr. G
Hear the history and heart of ICR’s newly appointed President and Chief Operating Officer, Dr. Randy Guliuzza. He has served as ICR’s National...

ACTS & FACTS
'Doing Business' in Good Times and Bad
No doubt many of you, like me, have been earnestly looking for the return of the Lord Jesus Christ. He called all believers to be godly “salt”...

APOLOGETICS
Sentinels Are Needed in Perilous Times
Watch out! Dangers lurk everywhere—these are surely perilous times.1 One of the apologetics-exhorting themes in Jude’s epistle...

ACTS & FACTS
Why Don't Raindrops Bomb Butterfly Wings?
Okay, I admit most folks have probably not thought to ask this creation question. But a bigger question gets answered when we examine the fantastic...

ACTS & FACTS
Believe Anyway
by Scott Arledge and Brian Thomas, Ph.D. Some within the creation community make the claim that they would believe God’s Word about the age...

DISCOVERY CENTER
The ICR Discovery Center for Science & Earth History Updates*
Plan your trip at ICRdiscoverycenter.org, where you’ll find ticket information, discounted rates for nearby hotels, and links to other...

ACTS & FACTS
Human Activity and Vertebrate Evolutionary History
God gave humans a dominion mandate1 and expects us to exercise responsible stewardship “over all the earth.”2 After...

ACTS & FACTS
Biological Bounceback at Mount St. Helens
Early one bright Sunday morning, Mount St. Helens looked as picturesque as it had for hundreds of years. Suddenly, an earthquake shook loose the north...

ACTS & FACTS
Is Creation Evidence Ambiguous?
Is evidence for creation ambiguous? Could an honest seeker of truth reasonably conclude there is no God? Is the evolutionary old-earth story a reasonable...