1. Introduction
Location Close to Jabal Misht
Time 08:30 a.m. – 05:00 p.m.
GPS coordinates (Latitude/Longitude) 23° 14.920'N 56° 57.148'E
Figure 1: A visual representation of the study area (marked with a green arrow) on a road map. (Google, 2013).
The field trip to Ibri took place on the 11th of November and was conducted by Dr. Celiné Ducassou. Ibri is part of the A’Dhahira region. The outcrop that was visited lies 50 km east of Ibri and 3 km west of Jabal Misht. The study area has pointed out on a road map in Figure 1.
Figure 2: The localization of the study area on the geological map of Ibri (modified after Janjou et al. 1986 Google, 2013).
The study area has also been localized on a geological map in Figure 2. This field excursion was related to the turbidites of the Matbat Formation and the main aim of this trip was to log the sedimentary series, measure the paleocurrent and to perform paleocurrent analysis. Such analysis would help in understanding and interpreting the paleoenvironment.
After arrival on the site, a brief introduction to the geology of the vast area was done by Celiné Ducassou.
Oman has such an immense geological history. The order of the major rock units in Oman are (from old-young):
Autochthonous A – Autochthonous B – Hawasina Nappe – Samail Nappe
At first, there was the deposition of Autochthonous A unit which was followed by Autochthonous B and these two units were separated by an unconformity. Later, the Hawasina Nappe was thrusted over the two units. In Late Cretaceous, Samail Nappe was thrusted (obducted) over the Hawasina Nappe.
Every rock group has a different depositional environment. For example, the Kawr group represents the Oman Exotics and is composed of distal sediments (chert). Closer t...
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Lowe, D.R. (1982). Sediment gravity flows: II. Depositional models with special reference to the deposits of high-density turbidity currents. J. Sed. Petrol., 52, 279-297.
Minoux, L. and Janjou, D. (1986). Geological map of Ibri, Sheet NF 40-2F, Scale 1:100,000, Explanatory Notes. Ministry of Petroleum and Minerals, Oman: Directorate General of Minerals.
Mutti, E. and Davoli, G. (1992) – Turbidite Sandstones. AGIP, Instituto di geologia, Università di Parma, 275 p.
Shanmugam, G. (2000). 50 years of turbidite paradigm (1950s - 1990s): deep-water processes and facies models- a critical perspective. Marine and Petroleum Geology, 17, p. 477-512.
Stow, D.A.V. and Shanmugam, G. (1980). Sequence of structures in fine-grained turbidites: comparison of recent deep-sea and ancient flysch sediments. Sedimentary Geology, 25, 23-42.
Marshak, S. (2009) Essentials of Geology, 3rd ed. New York: W.W. Norton & Company, ch. 11, p. 298-320.
Lithologically the Kimmeridge Clay Formation can be subdivided into four units (Figure 2), despite of beds at the base of the succession are poorly exposed. However, in contrast, the units from mid-eudoxus Zone to the top of the formation that are well seen in the Formation. At the base of the formation until the eudoxus Zone, the strata are made up almost entirely of bioturbated shelly clays and in between beds, horizons of oil and bituminous are present. The upper part of the Eudoxus Zone until the upper Pectinatus Zone the composition is kerogen-rich mudstones and coccolith limestone.
The shelf-edge includes carbonate-to-clastic facies transition and tectonic uplift and erosion of the carbonates followed by deposition of the clastics. The Saint Peter Sandstone is a well-sorted, almost pure quartz arenite deposited during a major mid-Ordovician low stand. Clastics spread across an exposed carbonate platform by transportation. This is shown by the well-rounded, frosted texture of the quartz grains.
Sedimentary rock from the older Silurian Period is further from the river banks (Geological map of Victoria, 1973). Mudstone, inter-bedded shale and greywacke depositions indicate the Maribyrnong River may have previously taken a different shape, and younger sediments have replaced the older sediments in more recent geological periods.
The site visited on this day was informally known as the Bedrock Knob (NTS grid reference: 120 342). It is in an area where patches of limestone and exposed bedrock are common. The bedrock is part of the Preca...
To identify the specific type, functions and time period of the artifacts, various archaeology books, reports, and journal were referred. The interpretation was then conducted by dividing the artifacts into different area on the map and investigating their relationships.
The coastal belt of the Franciscan Complex is composed of the youngest and least deformed units and makes up the western quarter of all Franciscan rocks. The rocks of the coastal belt are composed of arkosic sandstones, andesitic graywackes, and quartzofeldspathic graywackes interbedded with radiolarian chert (turbidite deposits) (Blake and Jones, 1981). These sedimentary rocks suggest a depositional environment of deep-sea fan systems with both oceanic and continental provenance. Parts of the belt show evidence of later metamorphism, principally due to subduction. Low-grade blueschist mineral facies are indicated by the presence of minerals such as laumonite and prehnite-pumpellyite (Blake and Jones, 1981). All rock units show evidence of thrust (imbricate) faulting due to the compressional forces of subduction. Ages of the coastal belt run from as little as 40 Ma (Eocene) to as old as 100 Ma (middle Cretaceous).
Later after the sea finally retreated occurred volcanic activity. Mountains rose through laccoliths, which also resemble volcanoes. These laccoliths differ in that they do not erupt. They shifted layers of rock upward in the shape of a dome. This specific piece of geologic morphology occurred at the end of the Cretaceous time. This marked the beginning of the Laramide Orogeny, which was a well-known period of mountain formation in western North America.
Plummer, C.C., McGeary, D., and Carlson, D.H., 2003, Physical geology (10th Ed.): McGraw-Hill, Boston, 580 p.
Basalt is a common extrusive igneous rock, there are a large number of volcanic provinces across Southeast Australia that have been found to contain basaltic lava flows. It is likely that these flows have come from volcanic activity caused by mantle plumes from the mesosphere. A variety of dating methods have been used to date these basaltic rocks, which have been aged from the Jurassic era right up to the late Cenozoic.
"Sedimentary Rocks." Backyard Nature with Jim Conrad. N.p., 18 May 2015. Web. 25 Oct. 2015.
regions of the earth can indicate which rock layer is older than the other. Trilobite fossils
...nder, C., Tsai, C., Wu, P., Speer, B. R., Rieboldt, S., & Smith, D. (1998/1999/2002). The permian period. Informally published manuscript, Biology 1B project for Section 115, University of California Museum of Paleontology, CA, Retrieved from http://www.ucmp.berkely.edu/permian/permian.php
Pipkin, Bernard W.. Geology and the environment. 6th ed. Belmont, CA: Brooks/Cole, Cengage Learning, 2011. Print.
The map was developed by the CIPD in conjunction with professionals and organisations around the world and is made up of the following 3 sections: