Jp. Moralcardona et al., THE ANALYSIS OF QUARTZ GRAIN SURFACE-FEATURES AS A COMPLEMENTARY METHOD FOR STUDYING THEIR PROVENANCE - THE GUADALETE RIVER BASIN (CADIZ, SW SPAIN), Sedimentary geology, 106(1-2), 1996, pp. 155-164
The analysis of quartz grain surface features from several sandy depos
its of the Guadalete River basin-Guadalete terraces, Miocene calcareni
tes and Aljibe sandstones-have yielded data of considerable value in t
he study of the provenance of these materials. The majority of the qua
rtz grains of the Miocene calcarenites present the same primitive surf
ace features as those of the Aljibe sandstones (generalised polishing
of their surface, mechanical marks enlarged by solution) and many conc
hoidal fractures and grooves corresponding to the high-energy environm
ent in which they were deposited. The quartz grains of the Guadalete t
erraces are mainly derived from the Miocene calcarenites (they show nu
merous fractures and polished grooves) and have undergone a later stag
e of evolution, forming isolated Vs and silica deposits corresponding
to a final fluvial means of transport. These data indicate a possible
evolution as follows: (1) Aljibe sandstones; (2) Miocene calcarenites;
(3) fluvial sands of the Quaternary terraces of the Guadalete River.
This evolution has been confirmed by study of the heavy mineral associ
ations and the petrology of these materials. Thus, quartz grain surfac
e features may be an extremely useful instrument for studying provenan
ce, determining the evolutionary path that various sediments of a regi
on have taken, thereby complementing the data yielded by the mineralog
y of heavy minerals and regional geology.