The Relevance of Rb-Sr, Sm-Nd, and Pb-Pb Isotope Systematics to Elucidation of the Genesis and History of Recent Andesite Flows at Mt. Ngauruhoe, New Zealand, and the Implications for Radioisotopic Dating

Download PDFDownload The Relevance of Rb-Sr, Sm-Nd, and Pb-Pb Isotope Systematics to Elucidation of the Genesis and History of Recent Andesite Flows at Mt. Ngauruhoe, New Zealand, and the Implications for Radioisotopic Dating PDF

Presented at the Fifth International Conference on Creationism, Pittsburgh, Pennsylvania, August 4–9, 2003 and published in: Proceedings of the Fifth International Conference on Creationism, R. L. Ivey Jr. (Ed.), pp. 285–303.

© Copyright 2003 by Creation Science Fellowship, Inc., Pittsburgh, Pennsylvania, USA. All Rights Reserved.

Abstract

Mt. Ngauruhoe in the Taupo Volcanic Zone of New Zealand erupted andesite lava flows in 1949 and 1954, and avalanche deposits in 1975. Rb-Sr, Sm-Nd, and Pb-Pb radioisotopic analyses of samples of these andesites, as anticipated, did not yield any “age” information, although the Pb isotopic data are strongly linear. When compared with recent andesite flows from the related adjacent Ruapehu volcano, the Sr-Nd-Pb radioisotopic systems plotted on correlation diagrams provide information about the depleted mantle source for the parental basalt magmas and the source of the crustal contamination that produced the andesite lavas from them. The variations in both the depleted mantle Nd “model ages” and the Pb isotopes also suggest radioisotopic heterogeneity in the mantle wedge 80 km below the volcano where partial melting has occurred, contaminated by mixing with trench sediments scraped off the interface with the subducting slab. Thus the radioisotopic ratios in these recent Ngauruhoe andesite flows were inherited, and reflect the origin and history of the mantle and crustal sources from which the magma was generated. By implication, the radioisotopic ratios in ancient lavas throughout the geologic record are likely fundamental to their geochemistry, characteristic of their origin and history rather than necessarily providing valid conventional “ages.”

Keywords

Andesite, 1949–1975 flows, Mt. Ngauruhoe, New Zealand, Rb-Sr, Sm-Nd, Pb-Pb, Radioisotopes, Petrogenesis, Depleted Mantle, Magma Genesis, Crustal Contamination, Subduction, Mixing, Inherited Radioisotopic Ratios, Invalid Conventional “Ages”

For Full Text

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

The Latest
NEWS
What's All the Flap About?
In the last few decades, there has been a lot of discussion by prominent paleontologists who imply that dinosaurs and birds are closely related. Many...

NEWS
Nearby Galaxy Has Almost No Dark Matter
A team of astronomers recently concluded that a nearby spheroidal galaxy, designated as NGC1052-DF2, contains very little, if any, dark matter.1,2 Since...

TESTIMONIALS
Building His Kingdom
Hello, my name is Andrew Infinger, and I work in ICR’s distribution center. As a full-time student and employee, I don’t have much time...

NEWS
Homo naledi had Lucy-Like Hips
Hips can reveal many things about fossilized organisms, especially when it comes to mammals. They can indicate the difference between species and even...

NEWS
Protein Discovery Confirms Design
Fungal infections can be a pain to eradicate. But new results show why these infections can take an even tighter hold on people or animals that are...