A down-column geochemical study of lower globigerina limestone with special reference to the 'soll' layers

Abstract

The globigerina limestone is reviewed with particular reference to the lower globigerina limestone and the occurrence of "soll" layers along this rock formation. Ten samples were taken from a vertical column of a quarried rock-face situated at Mqabba. Two "soll" layers ran across this column. The major elements quantitatively determined were calcium, carbonate carbon, chlorine, magnesium, phosphorus and silicon. The results show that the "soll" rock samples contained a higher percentage of silicon and lower percentages of calcium carbonate and magnesium carbonate. The "soll" rock samples also showed a lower magnesium / calcium ratio than the "non-soll" rock samples. These results have led to the proposition of a theory which states that "soll" rock was deposited during periods of partial allochthonous deposition from terrestrial sources. These disturbances in the normal depositional environment were probably caused by recurrent climatic changes.