Contents

List of colour plates		viii
List of tables		viii
List of figures		ix
Frontispiece		x
1 Executive summary		1-5
1.1	General	1
1.2	Summary of principal recommendations	1
1.2.1	A global reference network	2
1.2.2	Field methods for regional surveys	2
1.2.3	Geoanalytical requirements	3
1.2.4	Radioelement mapping	3
1.2.5	Data management	4
1.2.6	Implementation	5
Colour plates		6-14
2 General introduction		15-27
2.1	Geochemistry and sustainable development	15
2.2	The current status of geochemical mapping	18
2.3	The deficiencies of existing multielement datasets	20
2.4	Origin of the project	24
2.5	Organization of the project and authorship of the report	25
2.6	Future progress	27
2.7	Acknowledgements	27
3 Sampling and global mapping: a review		28-36
3.1	Introduction	28
3.2	Sample media	29
3.3	Sample spacing	33
3.4	A standardized global reference network	34
3.5	Reliability of the sampling process	35
4 A global geochemical reference network		37-45
4.1	Introduction	37
4.2	Sample media for a global network	38
4.3	Sampling logistics	39
4.4	Site location and the number of sites sampled	41
4.5	Sampling details	41
4.5.1	Regolith sampling	41
4.5.2	Drainage system sampling	42
4.5.3	Sample quantities, preparation and storage	42
4.5.4	Other important considerations	43
4.6	Production of a world map, based on GRN data	43
4.7	Summary of recommendations	44
5 Field methods for regional surveys		46-53
5.1	Introduction	46
5.2	sample media for regional surveys	47
5.3	Sample media in different physiographic terrains	49
5.3.1	Glacial, subpolar, permafrost regions	49
5.3.2	Temperate regions	50
5.3.3	Desert regions	50
5.3.4	Equatorial regions	51
5.4	Planning and execution of regional sample collection	51
5.4.1	Sample size	51
5.4.2	Sample spacing	51
5.4.3	Sample-site selection	52
5.4.4	Collection of samples	52
5.4.5	Field observations and measurements at the sampling site	52
5.4.6	Sample documentation and sample site documentation	52
5.4.7	Sample preparation and storage	52
5.5	Summary of recommendations	53
6 Geoanalytical requirements		54-64
6.1	Introduction	54
6.2	Review of geoanalytical methods	55
6.2.1	Introduction	55
6.2.2	Decomposition techniques	55
6.2.3	Analytical techniques	56
6.2.4	Waters and vegetation	57
6.2.5	General comment - need for independent quality control	58
6.3	Analytical requirements for international geochemical mapping	58
6.3.1	General	58
6.3.2	Geochemical reference network - analytical requirements	60
6.3.3	Use of standard reference materials	61
6.3.4	Proposed arrangements for reference sample analysis	61
6.3.5	National and international geoanalytical requirements	62
6.4	Summary of recommendations	63
7 Radioelement mapping		65-70
7.1	Introduction	65
7.1.1	General	65
7.1.2	Relationship between airborne and ground surveys	66
7.1.3	Ground gamma ray spectrometry	66
7.2	Airborne gamma ray spectrometry (AGRS)	66
7.2.1	General	66
7.2.2	Quality considerations in AGRS	67
7.2.3	Flight line spacing	67
7.2.4	Products from AGRS mapping	67
7.2.5	Other permanent records	68
7.3	Fall-out monitoring using AGRS	68
7.3.1	Principles of fall-out monitoring	68
7.3.2	Fall-out nuclides	69
7.4	Recommendations for global mapping	69
7.4.1	General statement	69
7.4.2	Use of existing data	70
7.4.3	Collection of new data	70
7.5	Concluding comment	70
8 Data management		71-82
8.1	Introduction	71
8.2	Databases	71
8.3	National and survey databases	72
8.3.1	Quality assurance	73
8.3.2	Sampling preparation and analysis	73
8.3.3	Databases	74
8.4	Levelling and normalization of existing data sets	75
8.4.1	Introduction	75
8.4.2	Parametric levelling	75
8.4.3	Non-parametric normalization	76
8.4.4	Use of airborne gamma ray spectrometry for levelling	78
8.5	Map projections	80
8.6	Map preparation	80
8.7	Geographical information systems (GIS) and image processing	80
8.7.1	Representation of geochemical data	81
8.7.2	Geographical information system (GIS)	81
8.7.3	Examples of GIS with geochemical data	81
8.7.4	Image analysis system (IAS)	81
8.7.5	Discussion of the benefits of GIS and IAS use	82
8.8	Summary of recommendations	82
9 Data applications		83-85
9.1	Introduction	83
9.2	Examples of specific applications	84
9.3	Summary	84
10 Implementation		86-89
10.1	Introduction	86
10.2	Organizational requirements	87
10.2.1	Project coordination, long-term continuity and sponsorship	87
10.2.2	World geochemical data centre	87
10.2.3	Regional coordination centres	88
10.2.4	Technical assistance for developing countries	88
10.3	Scientific and technical considerations	88
10.3.1	Provision of standard reference materials	88
10.3.2	Access to data and samples	88
10.3.3	Introduction of new techniques	89
10.4	Cost factors in geochemical surveys	89
10.5	Total project cost	89
11 Bibliography		90-99
11.1	References	90
11.2	Additional general references	97
12 Appendices - supplementary information		100-121
12.1	Introduction	100
12.2	Supplement to Chapter 2: Acknowledgements - supporting organizations	100
12.3	Supplement to Chapter 3: Excerpts from research relating to the project	101
12.4	Supplement to Chapter 4: Global sample collection	103
12.5	Supplement to Chapter 5: Drainage and soil sampling procedures for temperate; humid tropical; seasonally humid tropical regions	104
12.6	Supplement to Chapter 6: Geoanalytical methods	107
12.7	Supplement to Chapter 7: Additional information on airborne gamma radiation data collection and data reduction	112
12.8	Supplement to Chapter 8: Data management	115
12.10	Supplement to Chapter 10: Implementation	118
Key word index		122