TY - JOUR
T1 - Newly discovered submicron-scale weathering in quartz
T2 - Geographical implications
AU - Pope, Gregory A.
PY - 1995/11
Y1 - 1995/11
N2 - Quartz is regarded as one of the minerals most resistant to chemical weathering. Nevertheless, quartz does weather under certain conditions. Several geographic phenomena, including downstream sorting of fluvial sediments, the distribution of loess, and the absence of silica in tropical soils, may be directly or indirectly related to quartz weathering. Weathering may impact the use of quartz in geographic applications of geochronology and paleoenvi- ronmental analysis. This paper defines the molecular-scale mechanisms of chemical weathering in quartz, and presents the first examination of quartz weathering in the terrestrial environment using high resolution transmission electron microscopy (HRTEM). HRTEM images illustrate crystalline disintegration, or amorphization, of exterior surfaces and internal fractures of quartz sand grains collected from tills of the Eastern Sierra Nevada, California. Of several alternative mechanisms, in situ hydration of the crystalline matrix is the most plausible for quartz amorphization. Scale and mineral structure appear to be prominent factors in quartz amorphization; microenvironment and weathering rates may also be significant, but data are insufficient to make more precise generalizations.
AB - Quartz is regarded as one of the minerals most resistant to chemical weathering. Nevertheless, quartz does weather under certain conditions. Several geographic phenomena, including downstream sorting of fluvial sediments, the distribution of loess, and the absence of silica in tropical soils, may be directly or indirectly related to quartz weathering. Weathering may impact the use of quartz in geographic applications of geochronology and paleoenvi- ronmental analysis. This paper defines the molecular-scale mechanisms of chemical weathering in quartz, and presents the first examination of quartz weathering in the terrestrial environment using high resolution transmission electron microscopy (HRTEM). HRTEM images illustrate crystalline disintegration, or amorphization, of exterior surfaces and internal fractures of quartz sand grains collected from tills of the Eastern Sierra Nevada, California. Of several alternative mechanisms, in situ hydration of the crystalline matrix is the most plausible for quartz amorphization. Scale and mineral structure appear to be prominent factors in quartz amorphization; microenvironment and weathering rates may also be significant, but data are insufficient to make more precise generalizations.
KW - Electron microscopy
KW - Paleoenvironmental analysis
KW - Quartz
KW - Soils
KW - Weathering
UR - http://www.scopus.com/inward/record.url?scp=84987047968&partnerID=8YFLogxK
U2 - 10.1111/j.0033-0124.1995.00375.x
DO - 10.1111/j.0033-0124.1995.00375.x
M3 - Article
AN - SCOPUS:84987047968
SN - 0033-0124
VL - 47
SP - 375
EP - 387
JO - Professional Geographer
JF - Professional Geographer
IS - 4
ER -