Joined: Sep. 2006
I begin to understand why people call you names on this board. However, I have patience to engage in your present rambling explanations. But first you have to show some knowledge of the material that you presented.
What you (and Arndts and Overn) are not recognizing is the actual formation of crystaline structures from a homogenous melt. The melt may have 5 (or 7 or 9 or more) different elements that form a crystal structure. With these elements, you may have preferrential crystallization of one type of crystal in one zone and another type of crystal in another zone of the solidification front as the melt cools. Since there are MANY crystals in any rock there can be areas between the actual crystals that are amorphous in nature. A granite countertop would be pretty bland if this were not the case.
To carry on with the technical side of this discussion you have to understand some terms.
Face-Centered-Cubic, Body-Centered-Cubic, Hexagonal-Close-Packed. These are unit cells of a crystal.
The unit cells can combine into different geometries like, Cubic, Hexagonal, Tetragonal, Rhombohedral, Orthorhombic, Monoclinic, Triclinic.
Depending on the unit cell AND the lattice geometry, an impurity may be substituted either interstitially (between crystal atoms) or substitutuinally (replacing atoms in the crystal matrix) depending on the impurities atomic size and the crystal structure.
Also, impurities may be present at the crystal boundries because of linear defects or grain boundries in the crystalline mass.
OK? Are you still with me?
To summerize into usefull bullet points.
*WHOLE ROCK ANALYSIS CAN CONTAIN IMPURITIES FROM INTERSTITIAL, SUBSTITUTIONAL, LINEAR BOUNDRY, OR GRAIN BOUNDRY DEFECTS ALONG WITH AMORPHOUS AREAS OF THE ROCK.
*THE NUMBER AND TYPE OF THESE DEFECTS IS RANDOM. which means...
*THE NUMBER OF Rb AND Sr ATOMS IN ANY ONE WHOLE ROCK SAMPLES IS SOMEWHAT RANDOMIZED.
*A WHOLE ROCK ISOCHRON ANALYSIS WILL SHOW DIFFERENT POINTS ON A LINEAR LINE RELATIONSHIP.
*ALL OF THIS VARIABILITY WAS FROM AN INITIAL, HOMOGENEOUS MELT.
Dalrymple probably didn't engage Arndts and Overn because the argument they used against Dalrymple was so basically flawed why should he respond to such simpleton accusations.
Back to you AFDave.
****This information from my sophmore MatSci text. It fits since AFDave's arguments are very sophmoric in nature.****