| Popis: |
Monogenetic volcanic fields are group of short lived and small, typically mafic volcanoes that form clusters, alignments or distributed randomly over large territory. The geoheritage values of such volcanic fields are difficult to characterize due to the scale problem they pose within the commonly magnitudes larger regions than their footprints. Monogenetic volcanoes are defined by their simple geological architecture. Their geological and geomorphological diversity of them not detectable easily within the common spatial scale diversity estimates performed mostly with an aim to quickly identify geological and geomorphological diversity hotspots. Here we explore this paradox situation from three distinct, nearby large monogenetic volcanic fields – Harrat Rahat, Harrat Khaybar and Harrat Lunayyir - each considered to be an active volcanic system in the western Arabian Peninsula. Historic records documented 52 days eruption in 1256 CE nearby Madinah City at Harrat Rahat. Archaeological evidence (desert kites) and some direct radiometric dating indicate Holocene (< 5-ky) volcanism at Harat Khaybar. In contrast, Harrat Lunayyir experienced a failed eruption (e.g., magma has not reached the surface) in 2009. These young volcanic activities and proximity to large cities and infrastructure triggered an elevated effort to monitor volcanic hazards in the region. Geoheritage has recently been considered as an avenue toward developing resilient society against volcanic hazard. Geotourism has also been recently considered as a prime sector for investment for economic development especially in the volcanic fields of West Arabia. The rapid economic growth and the industrial need of raw materials put unprecedent pressure on the geoheritage of these volcanic fields threating the reduction of geodiversity of the region. Accurate method to estimate the geodiversity of these volcanic fields is in great need, however, to develop quantitative methods by using advanced GIS technologies is challenging. This is partially due to the nature of measuring geodiversity of volcanic fields and the quality and availability of accurate geological information capturing the volcanic geoheritage. Here we provide a qualitative approach first to define the volcanic geoheritage of these three volcanic fields applying the volcanic geology and associated facies mapping approach. Such method is promising as the arid climate and lack of vegetation-cover help to identify clearly the geoheritage of those regions fall beyond the volcanic edifices. This is particularly important in these fields where great variety of surface textures of pāhoehoe and ʻaʻā lavas as well as inter-edifice mixed arid terrestrial sedimentation occur. In addition, geological attributes of volcanic edifices such as geochemistry, petrological information and pyroclastic successions ordered in their volcanic hazard perspective been used to refine diversity elements. The utilization of remote sensing satellite data, high resolution terrain analysis methods and collating information on geoheritage elements such as archaeology, geocultural aspects and types of geotourism utilities are also considered. Combination of these data to the most up to date geological mapping information clearly showed the correlation of geodiversity with the maturity and longevity of volcanism of the studied volcanic field fields. |
