Origin of some hot springs as conceptual geothermal models

Hot springs act as natural discharge points of geothermal waters. Hot springs exhibit a wide variety of geothermal activities and hydrochemical constituents and occur in locations with varying tectonic backgrounds. The occurrence of hot springs is controlled by a number of natural geological, tectonic, geothermal and hydrogeological factors. These factors include the basic components of geothermal systems such as geothermal reservoirs, caprocks, heat sources, water sources and permeable pathways. Variations of these factors are characteristic of geothermal systems, such as geothermal systems of the basin type, fold-controlled type, fault-controlled type, magma-related type, and contact zone-controlled type. There are several geothermal systems of combination types, including geothermal systems of the basin and fault-controlled type, anticline and fault-controlled type, volcano and fault controlled type and so on. Forty-four conceptual models, shown in profiles, were used to schematically describe the origin of various hot springs and have been summarized and presented in this paper for better understanding the origin of hot springs. Hot springs may be the discharge points of regional and intermediate flow in a groundwater system where the local, intermediate and regional flow exist. Three challenges for the future studies of the origin of hot springs are also presented.