Project Geology
Introduction
The Ngayu project covers an area of 2,087 square kilometres and is found within the Orientale Province of northeast DRC, some 270 kilometres northeast of Kisangani and 380 kilometres west of Lake Albert on the border with Uganda. The project covers prospective parts of the Ngayu Archaean greenstone belt, which is one of a number of greenstone belts in the north-east Congo Archaean craton and includes the Kilo and Moto greenstone belts. These Archaean greenstone belts are the northwestern extensions of the Lake Victoria greenstone belt terrain which hosts a number of world class gold deposits, including Geita, North Mara and Bulyanhulu that were found and developed during the 1990s.
Loncor's Ngayu project property location
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Loncor Resources Inc. has an option agreement with Rio Tinto Exploration RDC Orientale SPRL for the exclusive gold rights at Ngayu covering 13 PRs ("Permits de Reserches" - exploration permits) totaling 2,087 square kilometres. Initially, Loncor's option agreement had an area of 4,550 square kilometers and covered most of the Ngayu belt but after a regional assessment of the belt, using airborne geophysical and geochemical surveys over a two year period, the area was reduced in February 2012 to 2,087 square kilometers.
Ngayu Project Infrastructure and Legal Tenure Plan
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Exploration commenced at Ngayu in the first quarter of 2010 following construction of the main field camp at Yindi.
A two pronged exploration strategy has been undertaken over the last two years at Ngayu: ground follow up (gridding, soil and auger sampling, pitting, trenching, geological mapping and core drilling) of known prospects within the Ngayu PRs such as Makapela, Yindi and Itali; and regional reconnaissance geochemical (Bulk Leach Extractable Gold, "BLEG") and airborne geophysical and remote sensing techniques in corporation with Newmont under a Technical Services Agreement to target additional new prospects in this densely forest terrain.
The Ngayu Greenstone Belt has a length of approximately 80 kilometres and a width of 40 kilometres and bears geological similarities to the Geita Archaean greenstone belt of Tanzania. In terms of size, the Ngayu belt is approximately three to four times the size of Geita, where the gold deposits which currently total 17 million ounces are found within banded ironstone formations ("BIF") or in close proximity to the BIF in other host lithologies. Similarly, the Ngayu project has well developed BIFs with a total potential prospective strike length of 130 km.
Ngayu Project: Archean Greenstone Belt geology with similarities to the prolific Geita Greenstone Belt in Tanzania (black line is original Loncor property boundary, prior to February 2012)
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A number of gold occurrences are found within the Ngayu greenstone belt, including the Company's current most advanced prospect, Makapela (more information on Makapela is available in the Map section of this page, below), Yindi and Itali. Yindi and the Imva Fold area have been the sites of historical alluvial and hardrock gold production during colonial times and Kilo Gold's Adumbi deposit is to the east of the Ngayu belt.
The following prospects, with details below, are located within Loncor's Ngayu Project area:
Makapela Prospect
Yindi Prospect
Itali Propsect
Regional Geophysical and Geochemical Assessment
All airborne geophysical data have been analyzed in detail by specialist Newmont geophysicists in Perth, Australia as part of the Technical Services Agreement between Loncor and Newmont. The objectives of the interpretation were to prepare a map showing the distribution and structural relationships of the different lithologies in the project area, and to identify and prioritize target areas for gold mineralization, in part using the Geita geological model.Ngayu Project Detailed Geophysical Interpretation by Newmont
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This interpretation resulted in four priority areas as being lithologically and structurally favourable for gold mineralization, as follows:
- The Imva Fold Area, where the BIF( Banded Ironstone Formation) has been deformed into a tight regional fold, with strike-parallel faults (probably thrusts) and quartz-diorite intrusive in the fold hinge and on the flanks.
- An early-formed, north-south trending structural corridor, in the Makapela-Itali area, with dioritic intrusives.
- The Anguluku area where BIF is interpreted to have been thrust against a basement high, at the intersection with the NW-SE trending Yindi structure.
- The northeast of the project area, along strike from the old Adumbi mine, in an area where folded BIF with strike-parallel faulting, is cut by a major north-south structure.
Regional Geochemical Stream Sediment (BLEG) Sampling
BLEG (Bulk Leach Extractable Gold) sampling is a stream sediment sampling technique that provides a relatively fast and reliable way of assessing large tracts of land, and has been particularly effective in defining targets within the Ngayu area. The sampling methodology and analytical techniques are proprietary to Newmont.Following successful orientation surveys in the Yindi and Makapela areas in 2010, three phases of BLEG sampling were carried out:
- Phase 1, carried out in March 2011, in which 418 samples were taken over the whole concession area, at an average sampling density of one sample per 10 km2.
- Phase 2, completed in September 2011, with the objective of more closely defining the anomalies outlined in Phase 1. A total of 192 samples were collected representing an average sampling density of one sample per 4 km2.
- Phase 3 was implemented in November 2011 in order to further delineate the sources of gold anomalism in selected target areas. A total of 129 samples were collected, but results are still awaited.
Target Generation based on Airborne Geophysical and Regional BLEG Surveys
Six high priority (H1 -- H6), seven medium priority (M1 -- M7) and four lower priority targets (L1 -- L4) have been defined based on the BLEG anomalies and the geophysical interpretation. The rationale for selecting these targets is as follows:- Targets H1, H2, H3 and M1 in Imva Fold Area: BIF occurs on the limbs of a WSW-ENE trending fold over a strike length of 25 km. More complex zones of folding locally occur on the limbs of this regional structure, which together with the presence of strike-parallel faulting, form structurally favourable sites for gold mineralization. Clusters of strong BLEG anomalies of up to 1,136 ppb Au are present (compared with background values of <3 ppb Au for the general area).
- Targets H4 and M2 (Makapela Area): The BLEG data indicate the presence of gold mineralization to the east and west of the Makapela prospect, in catchment areas independent of the Makapela mineralization. Both targets are interpreted to be underlain by the basalt-dominated package with thin BIF units, which hosts the Makapela mineralization. The Makapela area (and the eastern part of the Imva Fold) are transgressed by a north-south structural corridor which appears to be an early feature that has been the focus of granodioritic intrusives, and which probably also introduced mineralizing fluids.
- Targets H5, M3 and M4 (Bole Bole Area): These areas of anomalous BLEG lie within a sequence of metasediments, tuffs and interbedded BIF, in a structurally favourable zone where the regional strike of the greenstone belt changes from NW-SE to NE-SW.
- Target H6 (Anguluku Area): The area of anomalous BLEG data is underlain by BIF, and lies at the intersection of the NW-SE trending Yindi structure and E-W, strike-parallel faults. The latter are possibly thrusts which formed due to compression of the Anguluku lithological sequence against a basement dome immediately to the north. The BLEG data suggest that mineralization may have a greater strike extent than the 3 km indicated by artisanal mining in the area.
- Targets M5, M6 and L1 (Adumbi Trend): The BLEG data in anomaly M6 suggest that the BIF-associated mineralization at Adumbi may extend onto Loncor's property. Targets M5 and L1 are located 15 km and 30 km respectively along strike and may represent a NW extension of the Adumbi trend.
- Target L3 includes the Yindi mineralization. However, the southeastern anomalous catchment has not yet been investigated, and will be followed up probably by extending the soil grid.
- Targets L2 and L4 are relatively small and isolated BLEG anomalies. They will be confirmed by additional BLEG sampling before decisions on follow-up work are made.
Prioritized Regional BLEG Results
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These priority target areas are now being followed up on the ground by gridding, soil and auger sampling to define drill targets.