Stratigraphy and mineralogy of laterite beds near Ziarat, Quetta Division, Pakistan

Ferruginous aluminous laterite beds crop out in the Ziarat-Loralai area east of Quetta for a strike length of about 60 miles. The beds are steeply dipping, sometimes overturned and faulted, and have an average thickness of 8 feet.

Detailed mineralogical and chemical analyses were made on chip-channel samples from four sections of the laterite in the vicinity of the village of Ziarat. One of the sections, 9 1/2 miles southeast of Ziarat, is 21 feet thick and has an average content of 42 percent available alumina, 3.6 percent silica, and 31 percent Fe₂0₃. The other sections have an average available alumina content of less than 32 percent. The alumina minerals present are mostly boehmite and diaspore, with minor amounts of kaolinite.

The laterite beds, which are between the Dunghan Formation of Paleocene age and the Parh Limestone of Cretaceous age, appear to mark the Cretaceous-Tertiary boundary; if this relationship is confirmed by further work, it would be of considerable assistance in prospecting for aluminous rocks in this and other parts of Pakistan.