The Geology and Gravity Anomalies of the Troodos Massif, Cyprus

Over Cyprus there is one of the largest recorded gravity anomalies which reaches a maximum of over +250 mgal. This paper records the main geological features of the island, investigates the source of the gravity anomaly and correlates both lines of evidence in support of an hypothesis on the evolution and structure of the area. The topography of Cyprus, which lies in the north-eastern Mediterranean, is dominated by two east-west mountain ranges separated by the low-lying central plain of Mesaoria. The northern, Kyrenia range is part of the southernmost arc of the Tauro-Dinaric Alps, whilst the southern Troodos range is an igneous massif composed of basic and ultrabasic rocks of plutonic and extrusive character. The Troodos rocks fall logically into three main units: (a) the Sheeted Intrusive Complex; (b) the Troodos Plutonic Complex; and (c) the Troodos Pillow Lava Series. The Sheeted Intrusive Complex forms the major part of the Troodos massif and is a north-south basic dyke swarm cutting basic lavas. The dykes range in thickness from 1 to 15 ft. and form over 90% of the complex. Abundant evidence is available to substantiate the intrusive nature of this dyke complex. Its unique concentration and regularity is attributed to repeated intrusion coupled with intense erosion. The north-south orientation of the intrusives is thought to be due to the east-west tensional stress that was dominant throughout the evolution of the massif. The central part of the massif is occupied by the Troodos Plutonic Complex, a layered ultrabasic complex of batholithic dimensions in which the rock types range from central dunites and peridotites outwards through melagabbros and olivine gabbros to gabbros and granophyres. Field, mineralogical and geophysical data indicate that the parent material was of peridotitic composition. Although gabbros are, by far, the most abundant rocks exposed, it is considered that these represent but a minor percentage of a vast mass of underlying, high-density, ultrabasic material. Differentiation of the ultrabasic parent material is thought to have resulted in the gradual upward and outward change from central dunites and peridotite through melagabbros and olivine-gabbros to overlying gabbros and granophyres. Forming an incomplete ring around the Sheeted Intrusive Complex is the Troodos Pillow Lava Series, a very thick sequence of pillow lavas and their related intrusives. Although divided into two units on the presence of a partial unconformity,