Geomorphology and iron sand potential at coastal sediment morphology, Kebumen Regency

Abstract

Geomorphology is a landform that extends on the surface of the earth as a result of interactions between endogenous and exogenous processes. Landform classification based on morphometry, morphogenesis, and morphoarengement. Kebumen has attractive geological diversity. The potential of iron sand spread out as beach sand deposits. This research conducted to map landforms, including south coast region and analyze the distribution of iron sand sediment. The study used DEMNAS image analysis, a 1: 20, 000 scale with Arc-GIS software. Variables analysis includes elevation, aspect, roughness, hill shade, river pattern, and hill roughness accompanied by a field survey. Resistivity survey on old beach deposits morphology (2 locations) and young beach deposits (2 locations) to obtain data on the potential of iron sand. Measurement using OYO Model 2, McOHM Resitivimeter, Schlumberger configuration, and geophysical modelling using Res-2Din software. The landform in Kebumen consists of 33 units as structural, denudational, dissolving, fluvial, and coastal landforms. The Coastal Sediment landscape consists of 3 units, in the form of young coastal sediment, old coastal sediment, and fluvio marine sediment. The potential of iron sand is founded in young coastal sediment (M5) is about 764, 77 Ha, and old coastal sediment (M4) about 590, 84 Ha. Mineral compositions are olivine, pyroxene, hornblende, biotite, and impurities as quartz, plagioclase, orthoclase, rutile and calcite minerals. Coastal sand sediment in the Old Sediment is found 30-60 m depth with overburden up to 4 m. The potential of beach sand about 406, 686, 300 m3 similar with 1, 037, 050, 065 tons, total Fe estimated about 629, 696, 799 tons.

Geomorphosite Assessment at North Karangsambung -Karangbolong Geopark Kebumen, as Tools of Geotourism Development

“…Southern morphology is a hill that stretched eastwards in the form of a series of Paras Mts. and Prahu Mts as a synclinal ridge and includes geomorphological units S9.1 (Ansori et al, 2020). This morphology is characterized by regular hill and mountain forms with the flat hill, steep slopes, moderate-weak erosion.…”

“…Looking to the east, it is clear that the valley of S. Luk Ulo separates the difference in the morphology of the rock on the left from the rock on the right in the middle. The left landscape is included in the geomorphological unit of melange S13.2 hills with steep slopes and weak erosion (Ansori et al, 2020), characterized by isolated, irregular, prismatic hills. Apparent dips are generally to the southeast, with steep slopes separated by a narrow valley around them.…”

“…Morphology in the middle area is a strong undulating landscapehills that include structural geomorphological unit S13.7 (Ansori et al, 2020). This landscape is characterized by stepping slopes, land used as raindrop rice fields, found a large block of diabase around rice fields.…”

“…The northern series is Perahu Mt and Paras Mt. This kind of landscape is often referred to as the Amphitheater, a geomorphological unit of the anticline mountains S9.2 (Ansori et al, 2020). This valley is a former fold formed in Karangsambung but experienced a topographical reversal process; the anticline peak turned into a valley.…”

“…This valley is a former fold formed in Karangsambung but experienced a topographical reversal process; the anticline peak turned into a valley. The syncline valley turned into a synclinal ridge unit S9.1 (Ansori et al, 2020). The former anticline peaks are experiencing weathering, erosion, and avalanche processes.…”