During the period 1967 to 1971 a team of geoscientists carried out a programme of regional geological mapping in parts of Peru and a low-density regional geochemical exploration survey of the Western Cordillera of northern Peru. The work was funded by the UK Overseas Development Administration (ODA – now the Department for International Development, DFID) in collaboration with the Servicio de Geologia y Mineria (SGM), Lima, Peru (now INGEMMET). The geochemical exploration project was managed by a BGS geologist/ geochemist and supported by counterpart staff from the SGM.
Locational and analytical data, maps and interpretative unpublished reports were deposited at the SGM in Lima in 1971. The geochemical data are a long-term asset and continued interest in the results, particularly in recent years, has required that the data be made more readily available in a digital format.
The 1967–71 GENP project essentially pre-dated the era of data processing by computer. Locational and analytical data have now been digitised and stored as a CD-ROM database.
The unpublished report (Baldock, 1971) on the 3.5-year project has also been digitised for release on the CD-ROM. This gives references to other reports, and tables and figures are included as files readable using Microsoft Office applications.
Publications relating to GENP 1967–71 are:
Baldock, J W. 1977. Low-density geochemical reconnaissance in Peru to delineate individual mineral deposits. Trans IMM Vol 86 pp B63-72.
Cobbing J, et al. 1981. The geology of the Western Cordillera of northern Peru. Overseas Mem Inst Geol Sci No 5. (specifically Chapter 8: Reconnaissance mineral exploration of the Western Cordillera polymetallic mineral provinces in northernmost Peru, by J W Baldock. See also Chapter 9: Review of mineralisation and metallogy in the Western Cordillera polymetallic province of northern Peru (same author)).
The analytical data reported in this CD-ROM database were produced by the IGS laboratories, London (now the BGS analytical laboratories at Keyworth, Nottingham) in the period between May 1968 and January 1971. The analytical methods are summarised in the 1971 report (see file text.doc on the CD-ROM), which also describes the analytical work carried out in Peru.
Funding for the project was extremely limited, with the result that only a very restricted suite of elements was determined.
It should also be recalled that in the 1968–71 period the gold price was still fixed at $35/oz and the prime exploration interest was base metals. Absent data are indicated by blank fields in the database.
|Element||Detection limit (ppm)||*Results below detection limit given as:|
The sample location data have been digitised from a sample site map, as the original field sample cards and the port-a-punch cards were not retrievable in 1998/99. The sample site map was a paper copy – so, although the UTM co-ordinates for locations are given to the nearest metre, the true location of the original sample sites may vary by as much as 500 m, or in some cases even more (see below for technical information and caveats). However, it should be noted that GENP 1967-71 was a low-density regional exploration survey based on the collection of some 1260 samples at key sites within the 25,000 km² project area – a density of approximately 1 sample per 20 km².
Co-ordinates are from UTM zone 17 and the map datum used is the South American Provisional datum 1956.
The UTM co-ordinates have been calculated by an affine transformation of digitiser co-ordinates, using the calculated UTM co-ordinates of half degree latitude/longitude intersections as control points. Comparison of selected sample locations with visually identified sites on the drainage network, as shown on the 1:100 000 scale topographic maps, issued by the Institute Geogrifico Militar, suggests that most co-ordinates in this database are within 0.5 km of their likely position on the topographic map. In some cases the discrepancy could be up to 1.0 km but not more than 1.5 km. Some sites could have been plotted up-stream of their true position to preserve clarity on the sample site map, which is at 1:400 000 scale. In some cases, the plotting of sample sites on side streams some way above their confluence with the main stream is thought to be true, as the sample sites seem to be a short distance up-stream of tracks or mule-paths.
In the light of the above information it is recommended that further investigations of anomalous sites should take the presence of an anomaly as being within a limited area rather than exactly at the location indicated by the sample site co-ordinates. No information is available on the correlation between the topographic maps and GPS determined co-ordinates, but some translational error is to be expected.
Regional dataset (GENP – 1967–71) (files located in DATA subdirectory)
|Minimum Easting:||612 997 m||Maximum Easting:||819 050 m|
|Minimum Northing:||9208 449 m||Maximum Northing:||9500 742 m|
|Number of sites:||1345|
|Average density||1 sample per 20 km²|
|Fraction used||-80 BS mesh (-177 μm)|
|Elements analysed by AAS||Cu, Pb, Zn, (Co), Ag|
|Elements analysed by colorimetry||Mo, (As), (V)
Cold-extractable heavy metal (CxHM) by the Bloom test
Other datasets (files located in DATA subdirectory of CD-ROM)
- GENP Orientation (around Michiquillay): xls
- 56 samples from Michiquillay and surrounding catchments (see Figure 4 (file report/genpfg04.ppt ) in accompanying report).
- Sorochuco follow-up soil survey: xls
- One hundred and one sample analyses from the Sorochuco prospect.
- Soil samples from Gran Bretaa mine regional in Central Peru: xls
- Locations for samples from follow-up work in the Pomahuaca area: xls
Note: Additional data, collected during follow-up work around specific anomalies and reliant on locally performed analyses, may still be available from INGEMMET in Lima.
Some locational information concerning some of these samples has been included in report figures.
The CD-ROM should be referenced as:
BGS (2007). Peru Regional Geochemical Exploration Survey CD-Rom. Version 2.0. BGS International Regional Geochemistry CD-Rom Series. No 4. Peru. British Geological Survey, Keyworth, Nottingham, UK.
The CD-ROM also contains the following:
Baldock, J W. 1971. Geochemical Exploration of Northern Peru (GENP), 1967-71. (Unpublished report of the project).
BGS work in Peru
British Geological Survey
Tel: +44 (0)115 936 3143
Fax: +44 (0)115 936 3276
Collaborating organisation: Peru – INGEMMET
Instituto Geológico Minero y Metalúrgico (INGEMMET)
Avenida Canadá 1470,
Tel: 051-1 6189800
Fax: 051-1 2254540
( Apartado Aereo 889, Lima)
|readme.doc||MS Word file of information about the CD-ROM and Northern Peru Regional Geochemical Exploration Survey|
|readme.pdf||Information file in PDF format|
|genp.xls||Northern Peru Geochemical database in MS Excel 2003 format|
|genp.csv||Northern Peru Geochemical database in comma seperated variable format|
|genp.dbf||Northern Peru Geochemical database in .dbf format|
|mich.xls||Orientation survey (around Michiquillay)|
|soro.xls||Sorochuco follow-up soil survey|
|gbret.xls||Soil sample analyses from Gran Bretaña mine region in Central Peru|
|poma.xls||Locations for samples from follow-up work in the Pomahuaca area|
Various MapInfo files relating to the geochemistry data. Each element has an associated Workspace file
|text.doc||Text of previously unpublished report: Baldock, J W. 1971. Geochemical Exploration of Northern Peru (GENP), 1967–71, in MS Word 2003 format|
|genpfg**.ppt||Report figures in MS PowerPoint 2003 format|
|tables.xls||Tables 1 – 6 from report as sheets in MS Excel 2003 format|