The outline of a geological survey
2003.6.30 Hiroshi Hagiya
1) Purpose of the survey
The outline of the geology of Qalimare limestone area had been surveyed and revealed by B.Hathway (1995) and Mr. F. Inoke of Wing Investment Ltd. In the course of survey, the large-scale folding structure covering the whole area and existence of a fault were disclosed, and development process of the coral reef which formed limestone during the Miocene era was also restored in the drill core. However, due to the complicated structure and a lack of lateral continuity of the limestone, the problems in the stratigraphy reconstruction and the geological structure of the whole area including Qalimare limestone are left unsolved.
The purpose of the survey this time is not to obtain new geological data but to confirm at the site large structures, such as folding of a stratum which can be checked by the elementary geological survey technique, thereby enable to image the dynamic movement of the crust as the result of the collision of island arcs accompanied with expansion of the Lau sea basin after the Tertiary as a cause of building such a large-scale shortening structure.
2) The details of the survey
2 – a) Advance study
Usually, it requires foregoing research by literature study and reading of the geology map, but learning how to discern a rock kind and the way of use a clinometer and a hammer should come first since most of the students do not have basic knowledge on the given subjects. Provide opportunity for acquisition of minimum basic knowledge by furnishing a study aids and reading material and also provide them preliminary knowledge about the surface-of-the-earth situation of the whole area by showing it on the satellite images (Landsat-7).
2-b) Introduction
It is necessary to let students confirm as to where they are at and which direction they are facing to by looking at the map of the whole survey area. On the first day of the survey practice the students will study how to confirm their positioning by traveling around the survey area with the map in their hands so that they will acquainted with the survey area. Make presumption on the geology of the whole area including the upper reaches through the judgement of pebble scattering around in a dry river bed in the survey area. Learn how to use equipments, such as hand-held GPS and a walkie-talkie.
2-c) Survey
From the 2nd day the survey will be conducted by a group unit. There are three routes in the survey area and two groups will be assigned to each route to perform geological survey. The survey will be conducted at each outcrop by confirming its location , judging rock kind, checking the earth surface, measuring dips and strikes, so that deposition structure and a dislocation at each outcrop can be observed. In accordance with the results of these survey, the coloring by geological difference will be made on the map and, then, dips and strikes are filled in to make simple geology map (route map).
3) How to collect
Produce geology map and sectional view by putting 3 route maps together for students to interpret the whole geological structure. Make them understand that a folding and dislocation is the result of shortening structure of the whole stratum, and also make them study as to what it means by showing it on the satellite photograph. If the time allows, provide opportunity to observe the terrace deposits developed at the ridge of the southern portion of the survey area, and to examine uplifting trend and its cause in the Quaternary. The outline of the result of the survey will be announced in the meeting.