The Catoca kimberlite pipe, Republic of Angola: A paleovolcanological model

Abstract

The Catoca kimberlite pipe is among the world's largest primary diamond deposits. The Catoca volcanic edifice is only slightly eroded. Kimberlitic rocks of various facies compose a crater of about 1 km in diameter and a diatreme. The structure of the pipe and mining conditions of the deposit are complicated by intense intrapipe tectonic processes related to large amplitude subsidence. Based on geological data, we pro pose a structural model of the deposit and a paleovolcanological model of the Catoca pipe formed during a full cycle beginning with a stage of active volcanism and completed by stages of gradually waning volcanic activity and sedimentation. It is suggested that the banded tuffisitic kimberlite of the crater zone was depos ited at the stage of active volcanic eruption from specific pyroclastic suspension as a low viscosity mixture of crystals and aqueous sol rich in serpentine.

Post-Gondwana Africa and the vertebrate history of the Angolan Atlantic Coast

“…The Lucapa and Benguela fault zones established margins for the narrowest continental shelf in West Africa. The Lucapa Fault Zone can be traced inland to the Catoca diamond mine where it is characterized by kimberlites with U-Pb zircon ages of ~117 Ma (Pervov et al, 2011). The Luxinga Field, 80 km to the southwest of Catoca, has dates derived from kimberlites of 145-113 Ma (Pervov et al, 2011).…”

“…The Lucapa Fault Zone can be traced inland to the Catoca diamond mine where it is characterized by kimberlites with U-Pb zircon ages of ~117 Ma (Pervov et al, 2011). The Luxinga Field, 80 km to the southwest of Catoca, has dates derived from kimberlites of 145-113 Ma (Pervov et al, 2011). Activity on the Lucapa fault zone, taken with the chronology of the opening of the South Atlantic and the biochronology of fossils , constrains the formation of the continental shelf, as opposed to the South Atlantic opening, to late Early Cretaceous (Aptian), around 117 Ma.…”

“…One of these, the Cassange Depression (Triassic), predates the initial opening of the South Atlantic, and the second, the Catoca Diamond Mine, dates from the late Early Cretaceous, some 15 million years after Africa and South America began to separate, but during kimberlite emplacement on the Lucapa fault zone (Pervov et al, 2011).…”

Overview of Diamond Resources in Africa

“…The K03 pipe exhibits a higher proportion of cubic stones with green radiation spots on the surfaces. , in the vicinity of the Lova and Chicapa river basins (Pervov et al, 2011).…”

Major- and Trace-Element Compositions of Indicator Minerals that Occur as Macro- and Megacrysts, and of Xenoliths, from Kimberlites in Northeastern Angola

“…For this study, we analyzed samples to a maximum of 609 m depth. A new exploration project taking samples to a depth of 800 m started in 2010 [13]. Crater facies are found up to 270 m in depth, and are composed of epiclastic sandstones, coarse debris rimming the crater, and a higher concentration of volcaniclastic material at a lower depth of the crater [14].…”