The holocene tufa barrage system of Las Parras de Martín (Iberian range, Teruel)

A well-developed Holocene tufa system occurs in the headwaters of Las Parras River, Iberian Range (Teruel province). The longitudinal profile of the river shows two knickpoints downstream of two gorges known as Hocino de las Palomas and Hocino del Pajazo. The largest tufa build-ups in this area (49 m and 26 m thick) were found just downstream these two gorges and associated waterfalls. Barrage and cascade structures and facies suggest a rapid down-stream and vertical development of the tufa system. Between the knickpoints and upstream, the river valley displays a low-gradient (2%) and tufa deposits occur as laterally extensive terraces, with variable thickness (up to 8.2 m in El Batan) and fluvio-lacustrine tufa sequences associated to dammed areas. The Las Parras Tufa system represents a depositional environment including stepped fluvial systems with barrage-cascade and associated dammed areas separated by low gradient fluvial stretches. According to the chronological data, the development of Las Parras Holocene tufa occurred between 9.9 ky and 3.1 ky, with the highest growth rate from 5.5 to 3.1 ky, and a significant reduction of tufa activity during the last 2000 years. This evolution reflects the water availability in the area, and is coherent with changes in summer insolation during the Holocene.