GEOCHEMICAL CHARACTERISTICS AND EMPLACEMENT CONDITIONS OF IBAGUÉ
BATHOLITH (CENTRAL CORDILLERA, COLOMBIA): REGIONAL IMPLICATIONS
The purpose of this thesis is to study in detail granitic samples of the Ibagué Batholith near to the contact with the Cajamarca metamorphic complex (west of Ibagué City). The Ibagué Batholith is a huge granitoid body with a N-S orientation consisting of many magmatic pulses that took place during Jurassic times (150-188 Ma), and comprises diorite, quartz diorite, granodiorite and quartz mozonite rocks. Although this body is in contact with the Cajamarca Complex, in the literature there is no clear consensus as to the intrusion relationship between these two bodies. Furthermore, recent studies in the area determine Jurassic ages in the Cajamarca complex (146-157 Ma), younger than the previous Permo-Triassic published data. One possible interpretation for this inconsistency is a result of thermal resetting of older metamorphic ages. Following this hypothesis, the purpose of this thesis is to determine the depth of granitoid crystallization, obtaining pressure and temperature (P-T) conditions in order to discuss the possible thermal effects in the area. Detailed petrologic and field descriptions, mineral chemistry, bulk rock compositions and thermobarometric techniques (e.g., Al-in amphibole, average P-T) of representative samples collected near the Coello and Cocora rivers will be analyzed. The data obtained will allow the interpretation of the crystallization conditions of the Ibagué Batholith, and will contribute additional information about magma genesis and possible cortical contaminations. These results are important for the understanding of the tectonic evolution of the Central Cordillera, permitting the analysis of the geodynamic implications and the thermal history of the region.