U-Pb and Ar-Ar geochronological constraints on timing of deformation and peak metamorphism in the Central Africa Orogenic Belt, Yaounde Domain, Cameroon

The Central Africa Orogenic Belt (CAOB) and the Transaharan and Sergipano belts form a major West Gondwana suturing orogen affected by D-1-D-4 compressional deformation. Microstructural observations, mineral chemistry, zircon, and titanite laser ablation ICP-MS U-Pb dating, and biotite, muscovite, and K-feldspar Ar-40-Ar-39 age data are used to constrain the timing of rocks formation and D-1-D-4 events in the Yaounde Domain of the CAOB, as well as characterize the Neoproterozoic-Cambrian transition. The Yaounde Domain rocks were deposited on a pre-Neoproterozoic structure that was overprinted by a c. 1000-700 Ma mega arc/back-arc system and related Tonian to Ediacaran magmatism. Older U-Pb dates (1000 up to 2700 Ma) are inheritance from a pre-existing crust. The D-1-D-4 compressional events relate to the inversion of the c. 1000-700 Ma mega-rift system. New dates at c. 700 Ma, c. 630 Ma, c. 580-555 Ma constrain the timing of D-1, D-2, D-3+D-4, respectively. The peak of accompanying metamorphism occurred at 614 & PLUSMN; 4 Ma during D-2. This was followed by a c. 115 Ma period of deformation-driven crustal exhumation and cooling that extended into the Cambrian. New data document short episodes of rapid denudation and cooling (up to 0.9 km/Ma and 40 & DEG;C/Ma at c. 578 Ma in gneiss and up to 5 km/Ma and >125 & DEG;C/Ma at c. 555 Ma in micaschist). It is proposed that the CAOB and correlative belts are parts of the orogenic hinterland formed from accretion and collision between the West African Craton and the Sahara Metacraton precursor. The correlated belts appear to represent the result of a protracted tectono-metamorphic and magmatic process that started in late Mesoproterozoic (c. 1167 Ma) and continued through the Neoproterozoic to the Cambrian (c. 500 Ma).

Automated summary

The Central Africa Orogenic Belt (CAOB) and its neighboring belts underwent compressional deformation events labeled as D-1 to D-4, which occurred between the Neoproterozoic and Cambrian. Through various analyses, researchers were able to determine the timing of rock formation and the different compressional events in the Yaounde Domain of CAOB. The data also revealed the presence of inherited crust from older periods and provided insights into the tectono-metamorphic and magmatic processes of the region.