Pre-3000 Ma thermal history of the Archean Kaap Valley puton, South Africa

The Kaap Valley pluton is one of several early Archean (3200-3500 Ma) tonalitetrondhjemite plutons that surround the Barberton Greenstone belt, southern Africa. Precise dating using single-grain 207 Pb/ 206 Pb evaporation of zircon and 40 Ar/ 39 Ar laser step-heating of hornblende and biotite indicates that, in its interior, the Kaap Valley pluton preserves a memory of its initial intrusion and cooling, which spanned a time from 3225 to 3142 Ma. The pluton also records the effect of a low-temperature thermal event at its margin as seen by a 40 Ar/ 39 Ar biotite age of 3035 Ma, which is perhaps related to hydrothermal activity and gold mineralization in the adjacent Barberton Greenstone belt…

Elements of the Archean thermal history and apparent polar wander of the eastern Kaapvaal Craton, Swaziland, from single grain dating and paleomagnetism

Abstract Single grains of zircon, hornblende, biotite and feldspar have been dated to define the thermal history of the Archean Mbabane Pluton, Swaziland. Coincident207Pb/206Pb zircon and40Ar/39Ar hornblende ages suggest that the pluton underwent rapid cooling to about 450°C at the time of emplacement at ∼ 2690 Ma. Because the Mbabane Pluton is one of a suite of granites which represent the last major Archean intrusive event in the eastern Kaapvaal Craton, this time of emplacement marks the end of cratonization. Much younger biotite and feldspar ages indicate argon loss, perhaps due to several low-temperature events related to dike intrusion at 2000–2300 Ma. From such a thermal history, the…

Elements of the Archean thermal history and apparent polar wander of the eastern Kaapvaal Craton, Swaziland, from single grain dating and paleomagnetism (Dataset)