Geochemistry of magnetite from Fe-skarn deposits along the central Loei Fold Belt, Thailand

Abstract

Fe-deposits in Thailand are mostly located along the Loei Fold Belt in Central Thailand. The study areas, Khao Lek (KL) and Khao Thab Kwai (KTK), have Fe-deposits hosted in contact metamorphized Permian limestone and Permo-Triassic volcanic rocks. Magnetite forms over a wide range of geological conditions and incorporates various trace elements into its cubic spinel structure. The KL and KTK Fe-skarn deposits are mainly composed of massive magnetite. The main discriminator elements for magnetite are characterized by the distribution of Mg, Al, Si, Ca, Ti, V, Cr, Mn, Co, Ni, and Cu. Thus, this study focused on the chemical characteristics of magnetite to identify the origins of the iron ore deposits. This study investigated the trace element chemistry of the magnetite using laser ablation inductively coupled plasma mass spectrometry. The high Ca + Al + Mn and low Ti + V and Ni/Cr + Mn contents of hydrothermal magnetite in the KL and KTK deposits support a typical skarn origin, and the textural and trace element features of the KL and KTK magnetite are analogous to those of typical calcic-Fe skarn deposits worldwide.