Sedimentary’ units

The geological history of this area seems started by sedimentary units of Mesozoic - Cenozoic age which contains Fylisch and Limestone. These units were influenced by intrusion of volcanic and sub volcanic rocks in Miocene - Oligocene age. These igneous rocks mainly contain dacite, trachyandesite and andesite. These young volcanic units exposed in KIAMACCI Mountain vastly and their... 

Figure 10.11. Isotopic composition of sedimentary sulfide and sulfate through geologic time in terms of histograms of 834S values for units of various ages. The Phanerozoic portion of the sulfate record is the best documented. Prior to 1.2 billion years ago, the 834S values of sulfate are restricted primarily to sedimentary barite (BaS04). The later Proterozoic and Phanerozoic record of 834S of sulfide is a construct based on a 40%c difference between sedimentary sulfide and sulfate. Numbers refer to Precambrian sedimentary units. These are described in Holser et al. (1988). (After Holser etal., 1988.)...

The more recent (Neonile) sediments in the area include the Masmas formation (clay and sandy silts deposited some 40,000 years ago). Neonile sediments called the Sahaba formation are younger (ca. 20,000 B.C.), and, as seen in Figure 1, these sediments cover much of the area bordering the modern flood plain on which most of the Predynastic sites are located. Some chemical differences are seen between these two Neonile sedimentary units... 

Below Unit B a silty sand layer (Unit C) was encountered in the cores taken between the mouth of the Great Wadi and the center of the Kom el Ahmr. Unit C contained a sequence of Old Kingdom to late Predynastic artifacts dating from about 2500 B.C. to 3200 B.C. Below Unit C, a very compact, well-sorted thick layer of Nile clay and sand was encountered (Unit N). No cores or trenches reached below this sedimentary deposit. Unit N contained occasional Predynastic ceramic and flint artifacts. Samples were collected from each 10-15-cm auger cut within each sedimentary unit in each core or trench. In addition, numerous samples of the Neonile deposits and other sediments from the nearby low desert and Great Wadi were taken for analysis. 

Table I. Definition of Sedimentary Units from a Typical Core Sample from Vicinity Between Kom el Ahmr and the Edge of the Cultivation Zone...

This research on pottery has three aspects. The ability to differentiate with trace elements different sedimentary units allowed us to conclude that pottery was produced from Nile deposits located in the immediate vicinity of the potter s workshop and kilns (25). The finer Plum Red Ware, most popular between ca. 4000 and 3400 B.C., and most common in cemeteries, was made from the same Nile sediments as the more common Straw Tempered Ware that dominated settlement ceramics. The Plum Red Ware was often fired in specific areas that may have behaved like natural wind tunnels (e.g., Locality 39 and 59 in Figure 1). Our more limited studies of Hard Orange Ware (a fine pottery most popular after about 3400-3200 B.C.) have shown that, although made from local Nile sediments, there was a significant... 

Vertical walls can form from resistant sedimentary units which have been rotated into a vertical orientation. Rock climbers work out at Seneca Rocks, in West Virginia, the remains of a resistant sandstone unit which is now vertical. 

The importance of stratigraphic studies and the identification of sedimentary units at extensively disrupted sites like Hierakonpolis can be illustrated by the excavations at locality II, where there is evidence for habitation (trash mounds and pottery) as well as industry (pottery kilns). This locality ofiered a unique opportunity to study Predynastic ecology because of the excellent state of organic preservation in an area where there was a clustering of multi-functional components (6,14). Four test pits were dug in one area through the site, in the direction NIO °E-SIO °W. The correlation profile is shown in Figure I. The oldest unit identified was Nile silt (Masmas formation). In some areas, this silt was covered by eolian and/or wadi sands, which probably represents a local feature of sand accumulation under arid to semiarid conditions. 

Aquifer sediments are ultimately derived from rock weathering. Arsenic concentrations in unmineralized rocks of the United States are highest in sedimentary units (particularly marine shales), but are also elevated in volcanic rocks and in metamorphic rocks derived from sedimentary units (Welch et al., 1988). Although mineral sources of As have been directly identified in only a few aquifer sediments to date, pyrite, arsenopyrite, and/or unspecified sulfide minerals are often proposed to be the primary source of As in ground waters (Gotkowitz et al., 2(XX) Nickson et al., 2(XX) Peters et al., 1999 Robinson et al., 2000 Serfes et al., 2000 Smedley and Kiimiburgh, 2001). 

GEOCHEMICAL INPUTS FOR HYDROLOGICAL MODELS OF DEEP-LYING SEDIMENTARY UNITS LOSS OF MINERAL HYDRATION WATER... 

Marker bed A distinctive sedimentary unit that is reeognizable throughout the deposi-tional basin. 

Studies of sedimentation on the MAP revealed large sequences of turbidites. Turbidites are sediments transported by turbidity currents that are rapidly accumulated sedimentary units (Weaver and Kuijpers, 1983 Weaver et al, 1998b). There are three different types of... 

The origin of these deposits is unknown, but any genetic hypothesis must explain (1) their presence in or near sequences of metamorphic rocks formed from marginal marine sedimentary units, (2) their proximity to Archaean granite-gneiss complexes with reactivated migmatite fringes, (3) ore occurrences in repeatedly faulted and chloritized zones and (4) their proximity to Middle Palaeozoic unconformities. ... 

The Novazza deposit is located near the southern border of the Collio Basin in one of the volcanic units of the lower Collio formation. In the area of the deposit the crystalline basement is composed of para-schists of low-grade metamorphic facies. These are unconformably overlain by a thick volcanosedimentary sequence that forms the lower portion of the Collio formation (Fig. 4). The lower sedimentary units (SI, S2 and S3, Fig. 4) are mainly coarse-grained basement-derived clastic deposits, typical of a high-energy environment. The upper units (S4 and S5) are mainly finer sediments indicative of evolution to a more mature lower-energy environment (the last is mostly made up of volcanic fragments). The thicknesses of all the sedimentary units vary markedly over short distances (Fig. 4). 

Brigand, F., Vasseur, G., Caillet, G., 1989. Use of well log data for predicting detailed in situ thermal conductivity profiles at well sites and estimation of lateral changes in main sedimentary units at basin scale. In Maury, V., Fourmaintraux, D. (Eds.), Rock at Great Depth. Balkema, Rotterdam. 

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