> From: Pim van Meurs [mailto:entheta@eskimo.com]
> Andrew: <<The isochron method can't be used with most radiometric
> methods. It can be used with the uranium decay chain. But, as we
> really don't know how the stuff forms in the first place, I
> wonder if it's possible that the nature of creation can produce
> false isochrone evidence. Hydrogen doesn't fuse into uranium in
> one step.>>
>
> Actually most of the more often used methods in radiometric
> dating do involve the Isochron method or similar methods. Rb/Sr,
> U/Pb, Ar/Ar, , Sm/Nd, Lu/Hf, Pb/Pb. What 'stuff' are you refering
> to that we do not understand ? And why are you confusing fission
> with fusion ?
Andrew: <<Stuff=U238, and I didn't confuse fission with fusion.>>
Let's see if I can understand your argument then. We don't know enough about nucleo-synthesis to understand isochron methods and radiometric dating ? If that is the case, could you please give an example how this could be relevant to radiometric dating ?
In the mean time, I have found a table with isochron methods:
Isochron (OR CONCORDANCE) methodology is applied with the following isotopes:
P D Di half-life (*109 yr)
87Rb 87Sr 86Sr 48.8
40K * 40Ar 36Ar 1.25
147Sm 143Nd 144Nd 106
176Lu 176Hf 177Hf 35.9
187Re 187Os 186Os 43
232Th * 208Pb 204Pb 14
238U * 206Pb 204Pb 4.47
Another interesting feature is that when looking at the abundance of nuclides in nature, they suggest an old earth. (Table 8.3 in Dalrymple )
from
http://infidels.org/library/modern/dave_matson/young-earth/specific_arguments/moon_isotopes.html
Nuclide Halflife (years) Found in nature?
V-50 6 x 10^15 Yes
Nd-144 2.4 x 10^15 Yes
Hf-174 2.0 X 10^15 Yes
Pt-192 1 x 10^15 Yes
In-115 6 x 10^14 Yes
Gd-152 1.1 x 10^14 Yes
Te-123 1.2 x 10^13 Yes
Pt-190 6.9 x 10^11 Yes
La-138 1.12 x 10^11 Yes
Sm-147 1.06 x 10^11 Yes
Rb-87 4.88 x 10^10 Yes
Re-187 4.3 x 10^10 Yes
Lu-176 3.5 x 10^10 Yes
Th-232 1.40 x 10^10 Yes
U-238 4.47 x 10^9 Yes
K-40 1.25 x 10^9 Yes
U-235 7.04 x 10^8 Yes
Pu-244 8.2 x 10^7 Yes
Sm-146 7 x 10^7 No
Pb-205 3.0 x 10^7 No
U-236 2.39 x 10^7 Yes-P
I-129 1.7 x 10^7 Yes-P
Cm-247 1.6 x 10^7 No
Hf-182 9 x 10^6 No
Pd-107 7 x 10^6 No
Mn-53 3.7 x 10^6 Yes-P
Cs-135 3.0 x 10^6 No
Tc-97 2.6 x 10^6 No
Np-237 2.14 x 10^6 Yes-P
Gd-150 2.1 x 10^6 No
Be-10 1.6 x 10^6 Yes-P
Zr-93 1.5 x 10^6 No
Tc-98 1.5 x 10^6 No
Dy-154 1 x 10^6 No
(Dalrymple, 1991, p. 377) - Nuclides currently produced by natural processes are tagged with a "P"
For example, isochron methods are the most reliable radiometric dating methods. This is because they have a built-in indication that lets you know when the dating assumptions have been violated, which would make the date meaningless. The following methods were applied to a single sample of the Greenland Amsitoq Gneiss: [12]
Rb-Sr isochron 3.70 +- 0.14 billion years
Pb-Pb isochron 3.80 +- 0.12 billion years
U-Pb discordia 3.65 +- 0.05 billion years
Th-Pb discordia 3.65 +- 0.08 billion years
Lu-Hf isochron 3.55 +- 0.22 billion years
Further, look at the agreement between the ages of the oldest meteorites, by several different methods:
Number
Type Dated Method Age (x10^9 yr)
======================= ====== ====== ===============
Chondrites 13 Sm-Nd 4.21 +/- 0.76
Carbonaceous chondrites 4 Rb-Sr 4.37 +/- 0.34
Chondrites (undist. H) 38 Rb-Sr 4.50 +/- 0.02
Chondrites (all) 50 Rb-Sr 4.43 +/- 0.04
H Chondrites (undist.) 17 Rb-Sr 4.52 +/- 0.04
H Chondrites 15 Rb-Sr 4.59 +/- 0.06
L Chondrites (rel. und.) 6 Rb-Sr 4.44 +/- 0.12
L Chondrites 5 Rb-Sr 4.38 +/- 0.12
LL Chondrites (undist.) 13 Rb-Sr 4.49 +/- 0.02
LL Chondrites 10 Rb-Sr 4.46 +/- 0.06
E Chondrites (undist.) 8 Rb-Sr 4.51 +/- 0.04
E Chondrites 8 Rb-Sr 4.44 +/- 0.13
Eucrites (polymict) 23 Rb-Sr 4.53 +/- 0.19
Eucrites 11 Rb-Sr 4.44 +/- 0.30
Eucrites 13 Lu-Hf 4.57 +/- 0.19
Diogenites 5 Rb-Sr 4.45 +/- 0.18
Iron (+ St. Severin) 8 Re-Os 4.57 +/- 0.21
======================= ====== ====== ===============
([18], duplicate studies on identical meteorite types omitted.)
As shown in the table, there is excellent agreement on about 4.5 billion years, between hundreds of different meteorites and by several
different dating methods.
Further, studies on individual meteorites generally give concordant ages by multiple radiometric means. For example:
Meteorite Dated Method Age (x10^9 yr)
======================= ====== ====== ===============
Guarena w-rock Ar-Ar 4.44 +/- 0.06
13 sam Rb-Sr 4.46 +/- 0.08
----------------------- ------ ------ ---------------
Olivenza 18 sam Rb-Sr 4.53 +/- 0.16
w-rock Ar-Ar 4.49 +/- 0.06
----------------------- ------ ------ ---------------
Saint Severin 4 sam Sm-Nd 4.55 +/- 0.33
10 sam Rb-Sr 4.51 +/- 0.15
w-rock Ar-Ar 4.43 +/- 0.04
----------------------- ------ ------ ---------------
Juvinas 5 sam Sm-Nd 4.56 +/- 0.08
5 sam Rb-Sr 4.50 +/- 0.07
----------------------- ------ ------ ---------------
Y-75011 9 sam Rb-Sr 4.50 +/- 0.05
7 sam Sm-Nd 4.52 +/- 0.16
======================= ====== ====== ===============
([19]; duplicated methods omitted.)