Radiocarbon-dated ferricrete provides a record of natural acid rock drainage and paleoclimatic changes

Diel behavior of iron and other heavy metals in a mountain stream with acidic to neutral pH: Fisher Creek, Montana, USA

“…Fisher Creek drains an approximate 8-km 2 area between 2500 and 3230 m in elevation on the northeast flank of the mineralized zone. The occurrence of widespread ferricrete deposits (Furniss et al, 1999;Poage et al, 2000) and mineralized wetland sediment (Lovering, 1927;MacHardy-Mitman, 2002) indicate that before mining activities this drainage received high-metal loads produced by natural weathering of the surrounding sulfide mineral deposits. Metal loading was accelerated by mining activities in the 19th and 20th centuries, such that the headwaters are now severely affected by acid mine drainage (Kimball et al, 1999).…”

“…Previous studies of the Fisher Creek drainage have focused on the hydrogeochemistry of metals, especially Fe and Cu. Significant studies include investigations of metal loading and sources by the U.S. Geological Survey (Kimball et al, 1999), metal hydrogeochemistry by the U.S. Forest Service (Amacher et al, 1993;Amacher et al, 1995;Amacher, 1998), ferricrete deposits and implications for premining water quality (Furniss et al, 1999;Poage et al, 2000), overbank sediment (Hren et al, 2001), and copper bogs (Novak, 2000;MacHardy-Mitman, 2002).…”

Mine Wastes

“…• Mining wastes. These latter two terms highlight the fact that there are naturally outcropping sulfide orebodies and sulfidic rocks, which actively weather, oxidize, and cause acidic springs and streams (Eppinger et al 2007;Furniss et al 1999; Graham and Kelly 2009;Kwong et al 2009;Munk et al 2002;Posey et al 2000;Verplanck et al 2009). For example, the criterion for the separation of waste rock from metalliferous ore and for the classification of materials as economic or subeconomic is the so-called cut-off grade.…”

An investigation of acidic head-water streams in the Judith Mountains, Montana, USA

“…Examples of natural ARD have been reported from Colorado, Montana, and New Mexico in the western USA (McKnight and Bencala, 1990;Furniss et al, 1999;Posey et al, 2000;Bird, 2003;Sjostrom et al, 2004;Verplanck et al, 2009). Some of these streams are in pristine, undisturbed settings (McKnight and Bencala, 1990;Bassett et al, 1992), whereas others have been influenced by mining but show evidence of pre-modern acidic drainage (e.g., Fernández-Remolar et al, 2003).…”

“…Certain ferricrete deposits dated to http://dx.doi.org/10.1016/j.apgeochem.2015.05.012 0883-2927/Ó 2015 Elsevier Ltd. All rights reserved. >1000 y in age have been used as a record of climate change during the Holocene Epoch (Furniss et al, 1999;Sjostrom et al, 2004). Furthermore, Nimick et al (2009) have shown that a comparison of the trace element concentration of fresh Fe-oxide precipitates forming in a stream vs. adjacent ferricrete deposits may be used to compare the water quality of acidic streams before and after human disturbance.…”