Proximal hydrothermal alteration of the Carrapateena deposit

Abstract

Carrapateena is an IOCG (Iron Oxide Copper Gold) deposit, located west of Lake Torrens on the Eastern edge of the Gawler Craton. This deposit is located on the Stuart Shelf and is hosted by the 1850Ma Donington Suite granite. Carrapateena is a magmatic system controlled by fault structures and is compositionally impacted by hydrothermal alteration. The deposit partially is a magnetite orebody which is associated with chlorite alteration, while the top 1.5km of the deposit is predominately altered by hematite, with potassic and hydrolytic alteration. However, limited research on the host granite and alteration textures has been completed for this deposit. Investigation into the hydrolytic altered portion of the ore-system and granite surrounding is made to determine the geochemical, mineralogical, and timing of the Carrapateena deposit hydrothermal event history. Mineral textures between granite and hydrothermal minerals show the extent of the hydrolytic alteration through the granite. Typical alteration minerals in the host granite are hydrous forms of altered mica and feldspar. Combining their textures with trace element signatures of monazite, xenotime, and apatite provides insights into the hydrothermal history of the Carrapateena host granite, the Donington Suite. The geochronology associated with these minerals describes hydrothermal events predating the ore system and confirms the associated age for host granite surrounding the deposit.