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Southeastern Section - 58th Annual Meeting (12-13 March 2009)

Paper No. 40
Presentation Time: 8:30 AM-12:30 PM

AN OVERVIEW OF CAVE MINERALS ON THE ISLAND OF MALLORCA, SPAIN


HUNT, Glen A., Department of Geology, University of South Florida, 4202 E. Fowler Ave, Tampa, FL 33620, ONAC, Bogdan P., Department of Geology, University of South Florida/Emil Racovita Institute of Speleology, 4202 E. Fowler Ave, Tampa, FL 33620 and FORNÓS, Joan J., Earth Sciences, Universitat de les Illes Balears, Cra. Valldemossa, km. 7.5, Palma de Mallorca, 07071, Spain, gahunt2@mail.usf.edu

The island of Mallorca, located in the western Mediterranean Sea, is the largest and most central in the Balearic Archipelago. Samples were collected from eighteen caves. From a speleogenetic point of view, the Majorcan caves and shafts are divided into four categories: vadose shafts, vadose, phreatic, and littoral caves. In the present study, the majority of speleothems investigated were collected from caves assigned to the littoral category. All types of speleothems formed by dripping, flowing, and seeping water are well represented throughout most of the cavities on Mallorca.

Seventeen minerals, divided into four chemical groups, were identified and described using X-ray diffraction, infrared, thermal, and scanning electron microscope analyses. Calcite [CaCO3] is the only mineral found in every sampled cave. Aragonite [CaCO3], gypsum [CaSO4∙2H2O], and apatite-(CaOH) [Ca5(PO4)3(OH)] occur in speleothems from four different caves. In addition, a few other carbonates (ankerite [Ca(Fe2+,Mg,Mn)(CO3)2], dolomite [CaMg(CO3)2], hydromagnesite [Mg5(CO3)4(OH)2∙4H2O], and monohydrocalcite [CaCO3∙H2O], phosphates (ardealite [Ca2(SO4)(HPO4)∙4H2O], brushite [CaHPO4∙2H2O], collinsite [Ca2(Mg,Fe2+)(PO4)2∙2H2O], and taranakite [K3(Al,Fe)5(HPO4)6(PO4)2∙18H2O]), and silicates (illite [K0.65Al2.0Al0.65Si3.35O10(OH)2], montmorillonite [(Na,Ca)0.3(Al,Mg)2Si4O10(OH)2∙nH2O], muscovite [KAl2AlSi3O10(OH)2], and quartz [SiO2]) were identified in crusts, minute crystals, and earthy masses.

Based on the mineral inventory derived from our investigations, the following mechanisms are ultimately responsible for the precipitation of minerals in the Majorcan caves: (i) precipitation from percolating water (ankerite, aragonite, calcite, hydromagnesite, monohydrocalcite, dolomite, and gypsum), (ii) precipitation related to the freshwater/sea-water mixing zone (calcite, aragonite, and gypsum), (iii) reaction between the phosphate-rich leachates derived from bat guano and the underlying bedrock and clay sediments (apatite-(CaOH), ardealite, brushite, collinsite, taranakite, and gypsum), and (iv) phase transitions (aragonite to calcite inversion).

Session No. 16--Booth# 40

T3. Undergraduate Research (Posters)
Friday, 13 March 2009: 8:30 AM-12:30 PM
Geological Society of America Abstracts with Programs. Vol. 41, No. 1, p.45
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