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CONCLUSIONS
Our models show quantitatively what is
intuitively obvious: heterogeneous rocks
with coarse grain sizes present great chal-
lenges when obtaining bulk analyses. Care
must be taken both when choosing ran-
domly distributed analytical points and
when interpreting data from instruments
with different sampling volumes (Fig. 6).
Moreover, rocks with visible texture (lay-
ering, phenocrysts, etc.) must be carefully
sampled (if bulk compositions are needed)
to ensure that analysis locations are pro-
portionally representative of all textures
present (Fig. 6). Additionally, the ratio of
sample size to analytical size needs to be
considered, especially as modern instru-
ments resolve increasingly small analytical
volumes. The concept of a “bulk analysis”
likely needs to be revised for each system,
following the methods provided in this
study (Fig. 6).
ACKNOWLEDGMENTS
We acknowledge funding from NSF grants
EAR-1219850 (MCM) and EAR-1219761 (MDD).
Reviews from two anonymous reviewers were
thorough and strengthened this paper.
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REVISED MANUSCRIPT RECEIVED 25 OCT. 2016
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