In an εHf vs. 207Pb/206Pb age (Ma) plot, the regression line (best fit) can be drawn from the data point scatter. From the slope of such best fit line, average 176Lu/176Hf ratio can be calculated. Now what average 176Lu/176Hf ratio means? Also, how it is calculated from the slope of the regression line? For example, how the 176Lu/176Hf -0.025 value was calculated from the slope of the dashed line in the in the attached image?
please provide som additional information about the data behind the plot (or the link for the article, which the plot comes from), I am not sure that the dashed line is the regression line from the (all) data points
Sure Veronika. The link is attached. No, I guess the regression line is only generated from a fraction of data.
http://archenv.geo.uu.nl/pdf/Kemp%20et%20al%202010%20EPSL%20Hadean%20Crustal%20Evolution.pdf
.. I have read the article you provided, but I think that from the figure you pointed out it is not possible to read out/caltulate the Lu/Hf ratio. I think it´s missunderstanding, because due to this article...
Amelin, Y., Lee, D.-C., Halliday, A.N., Pidgeon, R.T., 1999. Nature of the Earth's earliest crust from hafnium isotopes in single detrital zircons. https://www.researchgate.net/publication/30863322_Nature_of_the_Earth%27s_earliest_crust_from_hafnium_isotopes_in_single_detrital_zircons
...I think that the Lu/Hf ratio is experimentally measured somehow, so in the mentioned figure are 3 regression lines for 3 data subsets and the slope of the regression line means only how "epsilon(Hf)" depends on "Pb/Pb Age" and the Lu/Hf ration is there only as an additional information about the data subset for that particular regression line.
I´m not familiar with this experimental array, so I leave the discussion :). Just one another link to Lu/Hf method:
https://homepages.uni-tuebingen.de/wolfgang.siebel/pdffiles/geochron_7.pdf
Article Nature of the Earth's earliest crust from hafnium isotopes i...
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