Objectives and Methods of Study

The thesis research was based on four weeks of field work over the 2009-2010 field seasons. Field work consisted dominantly of logging drill core from the various Aricheng prospects and visiting poorly exposed outcrops within the area. Drill core logging was supplemented with scintillometer readings to establish the degree of

radioactivity from background unaltered batholith into high grade mineralized segments of drill core.

The surface exploration carried out by Prometheus Resources to date for uranium in the Pakaraima Escarpment area of the Roraima basin has established a geological analogue to the Athabasca basin in Saskatchewan. There has been recent discovery of both

basement-hosted and unconformity-related uranium mineralization. The basement- hosted uranium prospects proximal to the Pakaraima escarpment occur in albitized granite breccia. These occurrences are fault-controlled and have associated zircon veining in zones of intense hematite-chlorite-albite alteration. The sodic alteration, hydrothermal zircon, and U-mineralization at Aricheng share characteristic features with the Valhalla U-deposit, Australia (Polito et al., 2009), as well as similarities to the Lagoa

Real deposit, Brazil, the Elkon deposit, Russia, and the Michelin deposit, Canada. Both alteration assemblages and U-mineralogy of these deposits relate to pervasive K- and Na- alteration common to IOCG-style mineralization. Using Olympic Dam as an example, the uranium mineralization might be expected to bridge granite/rhyolite interfaces where deeper levels are characterized by pervasive K-feldspar alteration with associated

magnetite-chalcopyrite, and shallower levels by albitization with associated hematite- bornite (Williams, 2010).

In IOCG deposits related to alkaline metasomatic alteration, the mineralization and alteration is generally associated with deep-rooted structural zones and faults. For

example, the Lagoa Real deposit in Brazil, is associated with a continental-scale fault. In the Kurupung, uranium-bearing structures have lamprophyre dyke associations attesting to the deep-seated nature of the fault system. The Aricheng district is characterized by deep K-alteration to shallow Na-alteration, consistent with IOCG systems. The timing of alkaline metasomatic activity is late magmatic and signifies the potential for regional 1995 +/- 15 Ma IOCG systems. The working hypothesis is that the alkaline

metasomatism and associated uranium mineralization relates to rapid unroofing of a K- rich granitoid along a mylonitic strike-slip fault active during the transition from Rhyacian (2.26-2.08 Ga) to the post-collisional Orosirian (2.07-1.96 Ga) stage of the Transamazonian orogenic cycle.

The economic mineral inventory of the Guyana shield is dominated by bauxite, and placer mining of gold and diamonds. Uranium exploration has also intensified since Cogema`s exploration activity in the early 1980`s. Although the Kurupung batholith is currently being explored for its uranium potential, it is also a prospective setting for lode gold and diamond sources. The batholith sits within the Kurupung mylonite zone, a deep-seated sinistral strike-slip fault system which was active between the 2103 +/- 3 Ma age of the batholith and the 1995 +/- 15 Ma age of uranium mineralization. Such deep- seated shear systems are somewhat analogues to mid-Tertiary detachment systems documented in the southwest United States Cordilleran (Davis et al., 1983; Reynolds and Lister, 1987). These host significant gold mineralization within detachment fault

breccias. Although sources of gold have been well established in the Guyana shield (Lowe, 2013), the location and age of the source of diamonds in the northern Amazon craton remains unknown (Santos et al., 2003). The source of alluvial diamonds in conglomerates at the base of the Roraima remains a quandary since Paleoproterozoic kimberlites and lamproites are not known in northern South America and rare in West Africa. Those that are known are either younger than the Roraima or are geographically located in an area that did not contribute to Roraima sedimentation.

The essential hypothesis of this thesis proposes that shear-hosted uranium mineralization is linked to post-collisional extension that characterized the terminal 1.96 Ga Orosirian phase of the Transamazonian orogenic event. Mylonitic shears in the basement were U- mineralized well before Roraima deposition. This study will therefore refute the original working hypothesis that U, P, Ti, and Zr were transported in oxidized basinal brines that precipitated U in basement faults well below the unconformity. Recognition of pre- Roraima uranium enrichment has significant ramifications for current interpretations regarding the unconformity related U-mineralization as best represented by the Athabasca basin in Central Canada and the McArthur Basin of Northern Australia. The

unconformity-type deposit may have reworked older uranium concentrations that existed in underlying basement prior to the deposition of continental sandstone successions. The following are the specific objectives of this research study: (1) detail the importance and significance of the Cr-rich sanukitoid-type Kurupung batholith using petrography and mineral chemistry; (2) establish the host rock mineralogy and the degree of alteration related to uranium mineralization by coupling mineral chemical investigations with detailed petrographic textural relationships at numerous mineralized zones; (3) establish the timing of uranium mineralization and hydrothermal zircon veining by documenting the detailed paragenetic relationships of zircon veins in uranium mineralized zones; (4) detail deposit scale elemental zoning in the Kurupung batholith by utilizing whole and trace element geochemistry; (5) constrain timing of mineralization and alteration using geochronology; (6) establish a working metallogenic model to apply in future exploration at both property and regional scales.