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GEOLOGIC PROSPECTING FOR MINERAL EXPLORATION IN THE TROODOS OPHIOLITE MASSIF OF CYPRUS
USING LANDSAT TM DATA
Freek van der Meer
Lecturer in Geology
International Institute of Aerospace Surveys and Earth Sciences ITC
Department of Earth Resources Surveys, Geological Survey Division
350 Boulevard 1945
Enschede, the Netherlands
Commission VII, Working Group 4
KEY WORDS: Algorithms, Correlation, Geology, Resources, Classification, CCSM, Sulphide Mining, Cyprus
ABSTRACT
The island of Cyprus hosts one of the best preserved ophiolite (i.e. remnants of oceanic crust and mantle) sequences of the world: the
Troodos massif. Lithologically the complex comprises a mantle series of ultramafic rocks overlain by gabbros and (plagio)granites. The
crustal sequence consists of dyke swarms with two series of pillow lavas at the top known as the lower pillow lava and the upper pillow
lava. Massive sulphide deposits, that have for long been the main income of Cyprus, occur at the contact between the lower and upper pillow
lava series, however this contact is difficult to map in the field. In this paper we explore the possibility of using advanced image processing
techniques to discriminate the main structural units to guide in mineral prospecting. A detailed field-spectral stratigraphic study forms the
basis for the selection of potential spectral end-members characterizing the TM image used. A new image analysis techniques, Cross
Correlogram Spectral Matching (CCSM), is introduced and succesfully applied to TM data from Cyprus.
INTRODUCTION ophiolite sequence of altered ultrabasic and basic plutonic igneous
rocks capped by intermediate and basic lava flows. This ophiolite
The Troodos massif of the island of Cyprus hosts one of the best
preserved ophiolite (i.e. remnants of oceanic crust and mantle) | ET rissene- Hoiosene marie 35° lone À mange
sequences of the world. Massive sulphide deposits occur near the Da er er bn en
top of this sequence. The copper mining history of Cyprus dates
back to Roman and Phoenician times (i.e. 3000 B.C.). Some 30
mines are located on the Troodos massif of which the largest
deposit, the Mavrovouni mine, produced 15 million tons of ore
averaging from 3.5 to 4.5% copper and 0.5% zinc. In the late
1970's all mines were closed due to the low copper prices. Only few
studies have been conducted to explore the use of remote sensing
for mineral exploration prospecting for sulphide deposits in this
semi-arid environment (e.g. Davidson et al. 1993) although the
Troodos massif forms an excellent test case since the geology has
been studied in much detail and many deposits have been found. In Fig. 1. The Geology of Cyprus
this paper we explore the possibility of using remote sensing (using
Landsat TM data) in combination with field spectroscopy to aid in sequence is among one of the best exposed in the world and has
mineral exploration. A new technique called Cross Correlation been studied in detail by various workers in terms of petrology and
Spectral Matching will be introduced and applied. mineralogy, tectonic setting, and mineral potential (Greenbaum
1977; Constantinou and Govett 1972; 1973). From the base to the
top of the ophiolite sequence, seven major lithologic units can be
GEOLOGY AND MINERAL DEPOSITS OF CYPRUS differentiated. The base of the ultramafic mantle sequence is formed
by medium to coarse grained harzburgites containing over 80%
The island of Cyprus (Fig. 1) is located in a tectonically active zone olivine and orthopyroxenes (enstatite). The harzburgites gradually
between the African lithospheric plate to the south and the Eurasian grade into dunites composed almost entirely of olivine. The base of
lithospheric plate to the north. Although many controversies still the crustal sequence is formed by layered gabbros which at the top
exists, most workers agree that Cyprus represents a slice of oceanic of the sequence often are intruded by dykes of granites. The
crust and mantle generated by rifting and subsequent up-thrusting gabbros are overlain by a sheeted dyke complex of closely-packed,
initiated during the middle Cretaceous. Geologically Cyprus can be nearly vertical doleritic dykes that are often metamorphosed at
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Im Maaatriohtíen-Middle Miosene chany] Pormian-Cretaeeeus limeatone
Sedimentary formations
Kyrenia
Troodos Ophielite
EN Upper Pillow lavag
Kl Lower Pillew lavad
(7 Basel areup
KA Sneeted diebese
tvi Plagiagrenites
Va) Gabbros
ES Dunite
R$ Horaburate
3) sorponunne
ÿ Limassol
rt
subdivided in four distinct geomorphological regions reflecting the green-schist facies. Above the sheeted dyke complex is a group of
changes in lithology: the Kyrenia range, the Mesaoria plain, the pillow lavas subdivided into a lower pillow lava and a upper pillow
Troodos chain, and the Mamonia and circum-Troodos complex. lava. The lower pillow lavas contain up to 5096 dykes and are of
This paper focuses on the ophiolite sequence exposed in the andesitic basalt and quartz andesite. Typically these lavas display
Troodos chain. plagioclase and pyroxene phenocrysts in a groundmass of altered
plagioclase. Albitization and celadonite alteration are common. The
The Troodos mountain range is formed by a 10 to 20km thick upper pillow lavas contain basalt, olivine basalt and ultrabasic
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