Summary guide to theMetallic Mineral Deposits Map of the Arabian Shield

Kingdom of Saudi Arabia

Scale 1:1,000,000

P. Lebret, G. Abdulhay, P. Béziat, A. Genna, E. Jaques, H.M. Kluyver,
P. Nehlig, P. Puvilland, I. Salpeteur, M. Shanti, and D. Thiéblemont,
with the collaboration of

J.M. Eberlé, J.L. Lasserre, and J.M. Leistel.

This document is a guidebook to accompany the 1:1,000,000-scale Metallic Mineral Deposits Map of the Arabian Shield, Kingdom of Saudi Arabia. The map was published in 1995 as a DMMR-BRGM joint special publication. It was compiled by Pierre Béziat, Jean-Jacques Bache and collaborators (see the map for a full list of names).

After a brief review of the old mining works in Saudi Arabia, a brief geodynamic history is presented to help the reader to understand how geologists perceive the geologic evolution of the Arabian Shield, today.

Following this, the main thematic data printed on the map are presented, and guidelines are provided for use of the map by non-specialists. In this respect, the format of the present booklet differs from the "Explanatory Notes" that usually accompany the Geologic Maps of the Kingdom.

Rather than providing an Arabic abstract as is usually the case, it was decided to translate the text in its entirety.

The Conclusions present possible future exploration and mining trends in the Kingdom of Saudi Arabia. Special emphasis has been put on sophisticated GIS-based processing of old and new geoscience data, as well as on recommendations for future detailed exploration to lay the foundations for a viable mining industry.

Abstract *

1. Introduction *

2. Objectives *

3. Geologic history of the Arabian Shield *

4. Ancient mining activity in Saudi Arabia *

5. The Metallic Mineral Deposits Map *

5.1. Geographic background *

5.2. Geologic background of the Shield *

5.3. Metallic Mineral Deposits presented on the Map *

5.4. MODS: the Mineral Occurrence Documentation System *

6. Main Metallic-Mineral districts of the Arabian Shield *

6.1. Base- and precious metals related to submarine volcanism (VMS type) *

6.2. Cr-Ti-Fe-Ni-Cu (PGE) mineralization related to mafic-ultramafic rocks *

6.3. Sn-W mineralization related to peraluminous post-collisional granite *

6.4. REE-Th-U mineralization related to HFSE enriched granite and syeno-granite *

6.5. Porphyry-type Cu-Mo, Cu-Au and W-Mo mineralization *

6.6. Epithermal gold and base-metal sulfide mineralization *

6.7. Mesothermal gold veins related to faults *

6.8. Sedimentary Pb, Zn, Cu or Ni-Mo mineralization *

6.9. Ti-Au-W residual placers *

7. Map Database *

8. CONCLUSIONS: POTENTIAL FOR MINING AND
RECOMMENDATIONS FOR FUTURE EXPLORATION TRENDS *

ILLUSTRATIONS

(bound in center, between the Arabic and English texts)

The objective of the Metallic Mineral Deposits Map of the Arabian Shield, hereafter referred to as the "Map", is to present anyone who is interested in the natural resources of the Kingdom of Saudi Arabia, with an outline of the metallic-mineral potential of the Arabian Shield. This has been achieved by showing the information on a wall-map.

The Map has a simplified geologic framework and suitable symbols for the mineral occurrences, to facilitate the appraisal of the main areas of interest and their metal potential. The Map was compiled from reports and maps published by the Deputy Ministry for Mineral Resources (DMMR) of the Saudi Arabian Ministry for Petroleum and Mineral Resources. The basic data result from work achieved since 1963 by geologists of DMMR and its Missions. The latter include Riofinex, and the USGS and BRGM missions.

The Map was published in 1995 under the following reference:

BRGM Geoscientists, Principal compilers P. Béziat, and J.J. Bache, with the collaboration of M.A Tawfiq, F Cottard, G Abdulhay, J Felenc, M. Bokhari, A. Al-Attas, and J. Caïa, 1995, Metallic Mineral deposits Map of the Arabian Shield, Kingdom of Saudi Arabia, DMMR-BRGM Joint Publication, Jiddah-Orléans, two sheets (north and south).

Since 1997, the Map is accompanied by a database for GIS users available on CD-ROM under MapInfo Format.

The following text is intended as an aid to all users of the Map or its database.

The aims of the Map and this guide are:

The Arabian Shield is the result of crustal accretion, much of which took place during the Late Proterozoic. The accreted elements were volcanic (island) arcs and their related plutons, sedimentary basins, and overthrust oceanic-lithosphere sheets.

The Shield is composed of low-grade metamorphic rocks and a few gneiss bodies. To the east, north and south, the Shield is covered by a thick succession of Phanerozoic sedimentary rocks. To the west, it is in direct relationship with the Nubian Shield that was a part of the Arabian Shield before the opening of the Red Sea, 25-30 million years ago.

The following brief history of the Shield is based on the results of geologic mapping at 1:100,000 to 1:250,000 scales, completed by analytical data for age dating, geochemistry and geophysics. Obviously, such a text has to be greatly simplified compared to the detailed scientific data on which it is based. Figure 1 shows a simplified geologic map of all of Saudi Arabia

The morphology and present shape of the Shield are mainly the result of relatively recent geologic events linked to the opening of the Red Sea. Although Early Proterozoic rocks occur in the eastern part of the Shield (a probable continental microplate), the formation of the Shield took mostly place in the Late Proterozoic, over a relatively short time span ranging from 860 to 540 Ma, which led to the formation of a >40-km-thick continental crust. Figure 2 shows the main morphologic units of Saudi Arabia.

Our understanding of the formation of the Arabian Shield derives mainly from the study of active island arcs in the Pacific, where similar formations accrete above subduction zones. The accretion of several such island arcs, formed between 860 (in the south) and 630 Ma (in the north and east), created the different "terranes"; each terrane has specific ages, rock assemblages and structural evolution, and collectively they are known as the Arabian Shield. The terranes are separated either by major suture zones, or by shear zones. Suture zones are marked by serpentinized ultramafics and associated rocks, known as ophiolites, which are remnants of subducted oceanic lithosphere (Jebel Ess, Al Ays, Bir Umq, Nabitah, Al Amar, Ad Dafinah, etc.). The shear zones are associated with gneiss domes that post-date the suture zones.

The final accretion of the different island arcs caused a strong tectonic deformation during what is known as the Panafrican orogenic period. Except for some suture zones characterized by mainly sub-vertical lineation, most Panafrican structures correspond to chains that either have a northwest-southeast (sinistral transpression: Najd faults) or north-south to northeast-southwest(dextral transpression) strike. Detailed studies show that these structures formed early as they were already active during the formation of the last volcanic arcs.

Major molasse basins formed at the same time in response to the accelerated erosion accompanying this mountain building. This was followed by the intrusion of a large number of orogenic and post-orogenic granitic plutons.

The last deformation is characterized by sinistral strike-slip along the "Najd" faults. This event created the Jibalah pull-apart basins, with thick sedimentary deposits along the major older faults and associated with major acid volcanism, as witnessed by the presence of rhyolites.

After the cratonization event, a generalized immersion of the Shield followed upon a period of erosion. The thick sandstone deposits at the base of the Phanerozoic succession witness of this gradual return to a marine environment.

Today's aspect of the Shield is largely linked to the opening of the Red Sea during the Tertiary era. This created uplift of the western Shield and strong erosion of the Proterozoic and overlying Phanerozoic rocks. Indirectly, it was also responsible for the extensive basaltic volcanism of the Harrats.

This history is summarized in figure 3, which is an updated version of the "Tectonic framework of the Arabian Shield", inset on the South Sheet of the Map. Based on this general geodynamic framework, the different types of mineralization found in Saudi Arabia can be fitted in their specific structural and metallogenic context:

The presence of thousands of ancient workings highlights the existence of an early, large-scale mining activity in Saudi Arabia, though most groups of workings were quite small. These workings, generally marked by excavations, tailings, slag piles, and village ruins, are scattered throughout the Arabian Shield. However, their locations are thought to have been largely governed by the proximity of water resources, and by ease of access to old roads (Sabir, 1991). Figure 4 shows the locations of ancient gold workings in the Shield.

Radiometric dating of charcoal from slags, as well as the study of glazed pottery remnants, suggests that mining activity may have begun around 3000 years ago (Schmidt and others, 1981), with an apogee during the early Islamic period, between AD 750-1250 (Twitchell, 1958). After that, mining declined, and remained inactive and mostly forgotten for almost a thousand years, possibly because the shallow ores that had been easily extractable with the then available technology had become mostly exhausted. Other arguments have been proposed, such as encroaching desertification and the consequent lack of wood fuel for smelting (Weisgerber, 1980).

Gold, and copper were presumably the main metals exploited by ancient miners in the Shield. Silver was only locally mined, mostly within the northeastern Ad Dawadimi district. Iron may have been mined in early times at Jabal Idsas, as indicated by magnetite waste and slag (Kahr, 1972). No sign of old mining of zinc or lead exists.

The earliest gold workings were probably in alluvial deposits, such as at Jabal Mokhyat (Schmidt and others, 1981), but the most abundant workings are found in coarse gold-bearing quartz veins lacking sulfides, such as at Umm al Qurayyat and Zalim. Ancient gold workings also occur in quartz lodes of polymetallic character, such as those found at Mahd adh Dhahab and Al Amar, where the gold occurs as minute complex grains in copper- and zinc sulfides. Mining of these lodes initially was mainly for their copper; the associated fine gold, however, has been recognized only recently after adequate extraction methods had become available.

The more typical copper workings are malachite-stained, sheared and hydrothermally altered corridors that generally affect volcanogenic rocks, such as those of Umm ad Damar and Muhadad.

The ancient production is difficult to evaluate. However, based on the volume and grade of many tailings and slag piles, it can be assumed that, over the centuries, around 5000 tons of copper, and 30 to 50 tons of gold were extracted from the main mining centers.

These ancient workings, most of which were rediscovered since the 1960s, are a precious heritage for modern exploration as they are excellent surface indicators of metal concentrations.

Today, all operational or future mines, as well as most of the significant mineral occurrences identified, were initially targeted from old workings.

In order to compile a wall map of the Shield with an acceptable size, it was decided to present the Map at the 1:1,000,000 scale. This is, moreover, an easy scale to evaluate distances, as 1 cm on the Map equals 10 km in the field.

The Arabian Shield (fig. 1) underlies much of the western half of the Arabian peninsula. Limited by the Red Sea to the west, it rises abruptly in an escarpment to a height of over 2000 m from the coastal plain, before gradually sloping to the east. The morphology of the Shield area itself consists of steep hills surrounded by sandy flats in which occasional floods occur after rainstorms. Figure 2 presents a simplified landform map of the Kingdom.

The geographic background of the Map uses the Lambert Conformal Conic projection (standard parallels 17º and 33º N.), modified from a Landsat mosaic of the Arabian peninsula at scale 1:1,000,000. The same background was also used for other geoscience maps of the Shield, e.g., those published by Johnson (1983; 1998). On the present Map, the geographic data, i.e. the latitude-longitude grid, main localities and roads, and the geographic names of areas of geologic interest, were simplified to a gray background.

There generally is a link between the type of rocks, their history and genesis, and the existence of mineralization. For this reason, a simplified geologic map forms the geologic background of the Metallic Mineral Deposits Map. On this background, the information derived from the computerized Mineral Occurrences Documentation System, or "MODS", was printed in black. Figure 5 shows an extract of the map, with its colored geologic background and mineral-occurrence information in black.

The main rock types in terms of their, primarily geodynamic, origin are:

Because the geochemistry of igneous rocks is a major tool for identifying types of mineralization, the simplified lithologic legend of the Map has been subdivided according to magma chemistry. The two main magma groups are related to their ratio of silica (SiO₂) compared to other chemical elements. When the SiO₂ value is over 50%, rocks are called felsic; when it is less they are called mafic. This classification is used for volcanic and intrusive rocks, but for the latter it is possible to be more precise. In fact, four groups are shown on the Map, ranging from felsic to mafic:

Because the history of the Shield is another major parameter in understanding mineralization types (younger rocks can show a mineralization that is quite different from older ones), the Map also presents the main age groups of Shield rocks.

Two age intervals (before and after 700 Ma) correspond to extensional dynamics, directly related to the opening of basins. The first period was the time when the Halaban, Hulayfah, Jiddah, Baish, and Baha basins were filled with deposits; the second is related to the Murdama and Jibalah set of basin deposits. All these basin deposits combine sedimentary rocks and volcanic products, which are potentially interesting for exploration

Three successive age intervals (>700 Ma, 700-650 Ma, and 650-530 Ma), correspond to three main steps in Shield "building". The 700 to 650 Ma period is related to compression tectonics in this area during the Proterozoic, rather than to extension tectonics. As yet unpublished data show that extension and compression dynamics must have been at least partly contemporaneous, as it can be seen that some extensional Najd faults were already active while the last arcs were still being thrust and deformed.

To complete this outline, the different faults should be mentioned that were plotted on the geologic maps of the Shield at 1:250,000 scale. Such faults are distinguished by their size (major or minor) and their type of movement; the latter can be vertical, strike-slip, or thrusting. Vertical, or normal, faults indicate tectonic movements that stressed and broke rock units near surface; commonly, this reflects a re-equilibration of the crust under extensional conditions. Strike-slip is caused by horizontal crustal movements. Thrusts result from tangential movements. A special category is that of ring structures and faults; these can be granitic ring dikes, or volcanic (acid to intermediate) "calderas" (generally collapsed) formed after a huge eruption.

5.3. Metallic Mineral Deposits presented on the Map

Four data elements are presented on the Map: 1) Category of occurrence, 2) Type of mineralization, 3) MODS number, and 4) Commodities of the occurrence. Figure 5 shows a typical extract of the printed map, at the original scale of 1:1,000,000.

The category of occurrence is described by a specific symbol. This shows the size of the mineralization and its potential economic interest, and the status of development (prospect, small-scale or large-scale potential mining project with feasibility study, or active open pit).

Each type of mineralization corresponds to a specific symbol related to the geometry of the mineralized body. This can be a:

5.4. MODS: the Mineral Occurrence Documentation System

Since 1971, the DMMR has recorded in a databank all Saudi Arabian mineral occurrences recognized in the field. Each point is recorded under a serial number, with a descriptive file (location, type of occurrence or mineralized body, condition of discovery, list of reference reports, chemical analyses, etc.). Each entry receives a sequential number, the MODS number (Delfour, 1975). Today, the databank contains over 5300 entries

Related to MODS, the size of the occurrence symbols provides a rapid identification of the potential economic interest of an area. It is thus easy to see if a zone has a good mineral potential, or if it is merely an interesting, but minor, geochemical anomaly. Beyond focusing on a specific area, the MODS number provides the gateway to more details by means of its various descriptive files.

The substances related to explored occurrences are shown by colored circles for the main commodities. The reader can use this thematic information directly, or he can cross-correlate it with other data to define a new exploration approach in a specific area, for example when selecting an area for detailed exploration. Twelve commodities are presented on the map: rare-earth elements, tungsten, zinc, iron (oxides or sulfides), gold, nickel, copper, barium, arsenic, silver, and manganese. For each, the secondary metallic elements associated to the main one are listed. Such secondary data are important when selecting permits for detailed exploration, or mining, as they could be interesting in terms of added value to the main commodity.

Some areas contain a large number of interesting occurrences for one type of commodity. Because of the impossibility to show each at the scale of the Map, they are indicated by an overprint pattern. The color of the overprint lines corresponds to a specific commodity: pink for thorium, brown for iron oxides, green for copper, olive green for chromium, blue for zinc, orange for lead, turquoise for barium, yellow for gold.

6. Main Metallic-Mineral districts of the Arabian Shield

The following text is a brief review of the nine main deposit types, with reference to their structural context and paleogeographic setting.

6.1. Base- and precious metals related to submarine volcanism (VMS type)

The volcanogenic massive-sulfide (VMS) type is one of the major metal resources of the Kingdom. The deposits include Cu, Zn (Pb), Ag, Au mineralization deposited on, or next to, submarine volcanic centers of oceanic-island-arc or back-arc affinity. Generally, they include mafic to felsic volcanic rocks with tholeiitic to calc-alkaline affinities. In Saudi Arabia, most of the VMS occurrences are related to intermediate to felsic rocks, known as the "Kuroko" type. Very few VMS occurrences are chalcopyrite-dominant in basaltic rocks, i.e. the "Cyprus" type. Locally, banded-iron jaspilite associated with felsic volcanics occurs as a sub-economic iron ore of the "Algoma" type.

The Map shows nine major VMS belts from south to north:

1) The Tathlith-Najran belt includes more than fifteen base-metal sulfide occurrences of the VMS type, with two potentially economic deposits at Al Massane (Cu, Zn, Au) and Kutam (Cu, Zn). In the eastern part of this belt, some Ni-rich gossans are related to disseminated to sub-massive graphitic-schist-hosted pyrite, pyrrhotite and pentlandite bodies, and are better classified as sedimentary type (see 6.8 below).

2) The Wadi Bidah – Wadi Shwas belt hosts over sixteen polymetallic VMS occurrences; two are of economic size: Al Hajar (supergene gold) and Jadmah.

3) The Khurmah – Al Muwayh belt includes four occurrences, two of which (Al Gharif and Ar Rjum) are of the sub-aerial epithermal type with a characteristic Ag-Ba-Mn association.

4) The Zalim – Afif – As Safra - Nuqrah belt follows the main Nabitah suture zone. It includes more than 45 occurrences of which about half are pyritic gossans with low precious- or base-metal contents. Nuqrah is a sedimentary/exhalative-rock (Sedex) gold and base-metals deposit.

5) The Samran – Jabal Sayid belt follows the Bir Umq suture zone and contains eight known VMS occurrences, including the major Jabal Sayid (Cu, Zn) deposit.

6) The Al Amar - Khnaiguyah belt (Ar Rayn terrane) hosts seven polymetallic VMS occurrences, Khnaiguyah (Zn) and Al Amar (Au, Zn) being economic deposits. Al Amar probably belongs to the epithermal subtype as exhalative Zn-Cu mineralization is known in the vicinity.

7) The Hulayfah - Hanakiyah belt may be considered as a northern extension of the Zalim belt.

8) The Khaybar - Al Ula belt (Yanbu suture zone) encloses five VMS Cu-Zn showings.

9) The most northerly Wadi Sawawin belt is clearly distinguished from the others by its Fe-oxide-jaspilite association (Algoma type). From the seventeen described occurrences, only the eight of West Shinfa/Sahaloola may hold economic prospects.

6.2. Cr-Ti-Fe-Ni-Cu (PGE) mineralization related to mafic-ultramafic rocks

These commodities, i.e. chromium, titanium, iron, nickel, copper, and (minor) platinum-group elements, are related to two main subtypes according to the host rock:

None of the occurrences found in rocks of these two types are of present economic interest.

6.3. Sn-W mineralization related to peraluminous
post-collisional granite

Most tin and tungsten mineralization is related to highly differentiated granites enriched in volatiles (F, P, Li).

Two subtypes are found in the Shield. They are the Bir Tawilah W-Sb-Bi-Mo mineralization in veins around granite cupolas, and the Silsilah Sn-F mineralization related to greisen alteration within a peraluminous granite intruding Murdama metasedimentary rocks. None of these occurrences is economic at present.

6.4. REE-Th-U mineralization related to HFSE enriched granite and syeno-granite

Some younger intrusives are sodic-alkalic granites enriched in high-field-strength elements (Ti, Y, Zr, Nb, Hf, Ta). Some are enriched in niobium, uranium, yttrium. thorium and rare-earth elements (REE), like the Ghurrayah prospect, and others are enriched in heavy REE (Nb, Zr, Y). None of these occurrences is economic at present.

6.5. Porphyry-type Cu-Mo, Cu-Au and W-Mo mineralization

Porphyry-type occurrences have only recently been recognized in the Shield. Commonly, the associated potassic intrusives are spatially associated with quartz ring-veins or aplitic ring-dikes. A common geochemical zonation has Cu-Mo anomalies in the core, Sn-W anomalies near the contact, and Pb-Zn-Ag-Au quartz veins farther out in the country rock. They are found in an inter-arc (microplate) crustal setting, or in younger sedimentary basins such as those of the Murdama and Jibalah.

These occurrences are clustered in eight major districts. These are the Fawarah Murdama basin, the Baid ad Jimalah – Umm Hadid belt, the Ar Ruwaydah belt (west of Al Amar), the Wadi Salamah – Al Khushaymaiyah Murdama basin, the South Afif terrane, the Ghurayrah block north of Khamis Mushayt, the Musayna’ah district (Cu-Au) west of Nuqrah, and the Al Ula -Khaybar district.

6.6. Epithermal gold and base-metal sulfide mineralization

Epithermal deposits are commonly associated with (sub-aerial) volcanic rocks that form the upper part of sub-volcanic potassic intrusives in a subduction-related arc setting. However, several epithermal deposits have recently been described from submarine andesitic-rhyolitic volcanoes, e.g., in the fore-arc basin of New Guinea.

The two major gold deposits of the Shield, Al Amar and Mahd adh Dhahab. are related to this type. The Umm Hadid silver occurrence and some Mn-Ba-Ag occurrences may belong to the same group.

6.7. Mesothermal gold veins related to faults

More than 700 vein-gold occurrences are reported in the MODS system and several gold districts can be delineated. Most veins are related either to shear zones or to secondary extensional flat dipping thrusts.

The shear zones are major brittle-to-ductile sinistral strike-slip Najd features that transect the Shield; examples are the Halaban - Zarghat fault zone, the Ranyah (Ar Rawdah) – Ad Dafinah fault, or the Al Wajh - Hamalyiah fault). Younger post-Murdama intrusive stocks, e.g., the Raha– Ali NaJadl - Mibari district, the Sukhaybarat – Al Jurdhawiyah district, or the Bulgah – As Shumta district, crosscut the secondary thrusts.

Some north-south pre Najd (so-called suture) faults, the Al Amar - Nabitah and Bir Umq sutures, are also associated with gold occurrences. These linear, sheared serpentinite belts, intruded by syn- or late tectonic diorite and granodiorite, were favorable for the precipitation of gold, as at Ghadarah and Hamdah. Pyrite, arsenopyrite, and sericite or chlorite and carbonate alteration are common in these shear zones where they are related to intrusive bodies.

The Sukhaybarat mine (21 t of gold, but nearly exhausted) belongs to this type, as do the Zalim and Ad Duwayah deposits, which hold good economic potential, and Bulgah, Hamdah, and Ash Shakhtaliyah.

6.8. Sedimentary Pb, Zn, Cu or Ni-Mo mineralization

During the Late Proterozoic, detrital material and graphitic shale with dolomite and locally barite, were deposited in a near-shore environment within inter-arc basins. Distal epiclastic-volcanic layers indicate volcanic activity along the basin margins.

Several disseminated Pb-Zn (Au-Ag) occurrences are related to this type, e.g. in the Ar Rjum – Al Gharif basin, the As Siham - Shaib Lamisah basin and the Ash Sha’ib basin. Stratabound copper in detrital rock has been recorded from the Ablah graben.

In the southeastern Asir Mountains, several Ni-Mo gossans are related to black shale enriched in pyrite, pyrrhotite and pentlandite. Though at present no occurrences of economic interest are known, the Farah Garan - Wadi Qatan belt could host this type of mineralization.

Along the Red Sea coast, Pb-Zn (Cu) mineralization is related to Tertiary detrital infilling of (half) grabens, which themselves were created by the tectonic activity accompanying the formation of this new ocean basin. The mineralization is a combination of red-bed type in detrital sediments, and younger Pb-Zn mineralization in Miocene calcareous-reef-related rocks, e.g., the Jabal Dhaylan prospect that belongs to a sub-type mixing unconformity features and hydrothermal activity.

Other Pb-Zn occurrences were discovered during oil-exploration drilling in the Paleozoic and Mesozoic Cover Rocks. Some of them are connected with salt-dome structures of Early Cambrian and Early Jurassic age.

6.9. Ti-Au-W residual placers

Some marine titanium-rich beach-sand placers were recognized in the coastal plain along the Red Sea shore. However, grades and tonnages are too small to warrant further work.

Gold placers have been explored downstream from certain large ancient gold workings, such as those in the Mahd adh Dhahab area. Although some "colors" were found during panning, the grades are not economic.

Exploration for tungsten (scheelite) and gold in the Quaternary terraces of alluvial piedmont deposits at the mouth of Wadi Unaybik, north of Al Wajh on the Red Sea coast, indicated low concentrations of these metals.

7. Map Database

In 1997, a database for computer-use was produced of the Map. This database contains all information shown on the paper map and was designed to be integrated into the main Integrated Geoscience Database of the DMMR. Figures 6 and 7 present some of the capabilities of this map database.

The interest of this database is to offer every GIS (Geographic, or Georeferenced, Information System) user the possibility to restitute all or part of the map on a plotter. This enables the generating of second-stage derived maps, for example showing only the major gold occurrences, or combining a type of occurrence (copper for example) with structural features and certain rock types. Using this database, exploration managers can decide for themselves where further exploration or development efforts could be interesting.

The CD-ROM, available in DMMR, contains the following files

(*= set of MapInfo file documents: .dat, .id, .ind, .map, .tab, .wor):

This database, contained on a CD-ROM, needs the following minimum hardware configuration for optimal access:

The software package for reading and extracting data without compatibility problems is MapInfo V4.

8. Conclusions: potential for mining and
Recommendations for future exploration trends

Since the 1950s, mineral exploration in the Arabian Shield has been carried out in three successive steps:

Future mineral-exploration activities in Saudi Arabia should include the checking of all remaining anomalies of potential interest. A much more important future activity, however, will be the constant reappraisal of available mineral data in the light of new scientific results and other developments. This is the reason why the Deputy Ministry for Mineral Resources has decided to make a considerable investment in the Integrated Geoscience Database, "IGD".

As in many parts of the world, the mass of available data has been growing almost exponentially, and it has become very difficult to handle data in even one domain because of their sheer volume. The IGD not only facilitates such data manipulation, but also enables the plugging-in of almost unlimited new data, as well as the future recombination of such data in ways as yet unimagined.

An example is the investigation of the potential of newly identified mineralization guidelines, such as the presence of adakites (Thièblemont and others, 1997, Jaques and Al-Jehani, 1998). To be more specific, future exploration efforts should include:

In conclusion, it is clear that part of the DMMR exploration work should include the continued checking of known anomalies. However, a completely novel type of work will have to be managed in parallel, in order to acquire a new overall geoscientific view of the Arabian Shield, to prepare new projects for mineral development over the next quarter century.

References

Béziat, P., Bache, J.J., (eds), Tawfiq, M.A., Cottard, F., Abdulhay, G., Felenc, J., Bokhari, M., Al-Attas, A., and Caïa, J., 1995, Metallic Mineral Deposits Map of the Arabian Shield, Kingdom of Saudi Arabia, Scale: 1:1,000,000, DMMR-BRGM joint publication, Jiddah-Orléans, two sheets.

Bhutta, M.A., 1966, Economic geology of the Aqiq-Umm ad Damar district [23/41A]: Saudi Arabian Deputy Ministry for Mineral Resources, Jiddah, Open-File Report DGMR-270, 114 p., 21 figs., 3 pls.

Bullock, S.C., 1936, Report on Umm al Qurayyat Mine [26/36]: Saudi Arabian Deputy Ministry for Mineral Resources Open File Report DGMR-OF-5, 6 p.

Delfour, J., 1975, Mineral Occurrence Documentation System – M.O.D.S. Revised Input Manual, Bureau de Recherches Géologiques et Minières, Open-File Report 75-JED-1, 79 p

Dolph, O.P., 1942, King Solomon’s Mine, Arabia: The Mines Magazine, January 1942, vol. 32, pp. 21-24.

Georgel J.M., Bobillier J., Delom J., Bourlier M., and Gélot J.L., 1989, Total-intensity residual aeromagnetic maps of the Precambrian Shield reduced-to-the-pole and upward-continued to 800 m above ground level: Saudi Arabian Directorate General of Mineral Resources Open-File Report BRGM-OF-09-15, 13 p.

Jaques E., and Al Jehani, A., 1998, Potential for Large-Tonnage Low-grade Deposits in the Arabian Shield. The Porphyry Copper Example, 5^th Meeting of the Saudi Society for Earth Sciences, 26-29 October 1998, Dhahran, Abstracts, p. 37.

Johnson P.R., 1983, Preliminary lithofacies map of the Arabian Shield: Saudi Arabian Deputy Ministry for Mineral Resources Technical Report RF-TR-03-2, scale 1:1,000,000, 72 p.

Johnson, P.R., 1998, Tectonic map of Saudi Arabia and adjacent areas: Saudi Arabian Deputy Ministry for Mineral Resources Technical Report USGS-TR-98-3, scale 1:4,000,000.

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