A New Contribution to the (IPC) Bouguer Map of a Gap Area in Mosul and Duhok Region (Iraq)

Yıl 2020, Cilt: 63 Sayı: 3, 329 - 344, 20.06.2020

Marwan Mutib Ahmet , Maan Abdullah , Fadhil Ali Ghaıb

https://doi.org/10.25288/tjb.638029

Öz

The purpose of the current study was to complete an important gap within the Bouguer map of Iraq implemented by the Iraq Petroleum Company (IPC). In addition, the collected data were processed with recent gravity concepts and methods to establish a new regional geological image. A total of 868 gravity points were measured and corrected.

The Bouguer anomaly map of the study area was initially drawn up with the parameters and equations used to construct the IPC map. The newly-produced map shows a very strong correlation with the old IPC results. A new Bouguer map of the study area was then constructed using modern parameters and equations. A comparison between the old and new maps illustrates the difference between recent and previous techniques.

The isostatic residual map shows the presence of over-compensated areas close to Chia Gara and Mateen and spreads to the Aqra zone with a negative value of up to -20 mGal. In contrast, there is under-compensation in the southern regions with positive isostatic anomalies of about 80 mGal. In the researched area there are zero compensation lines around the larger structures (Chia Gara, Mateen, Mangesh, Aqra, Piris, and Perat). In order to draw up the crustal thickness map, the Moho discontinuity depth was determined using topographic and Bouguer anomaly grids of the study area. In addition, the upper mantle anomalies were calculated by continuing the isostatic residual anomaly to 45 km upward and then removing the past isostatic residual anomaly, that was continued upward to 35 km. Several qualitative approaches were used to isolate the regional and remaining anomalies to analyze the gravity data, with an optimal upward continuation level of 14 kilometers generated for the large and small maps.

Anahtar Kelimeler

Gravity exploration, Gap area, Northern Iraq, Geosoft program

Kaynakça

• Abbas, M.J., Masin, J., 1975. New geophysical aspects of the basement structure in western Iraq. J. Geol. Soc. Iraq, Special Issue: 1-13.
• Al-Shaikh, Z.D., Saleh, S.A., Abdo, H.F.,1975. Contribution to the geology of Shaqlawa - Harir area, Iraqi J. Geo. Soc., Special issue, 55-67.
• Al-Shaikh, Z.D., Ahmad, M.M., 2005. New Contribution to the Geology of Mosul Area from Geoelectric Investigations. Rafidain Journal of Science, 16 (6), 132-147.
• Amos, M.J., 2007. Quasigeoid Modeling in New Zealand to Unify Multiple Local Vertical Datums. Curtin University of Technology, Department of Spatial Sciences, New Zealand, PhD thesis, 238 p.
• Asgari, M., Mehramuz, M., 2015. Estimate the Crust Thickness using the Gravity Data for the KopehtDagh Region. Indian Journal of Science and Technology, 8 (9), 513–517.
• Chen K.H., 2009. An Improved Approach for Terrain Correction: Application to Northeast Asia’s Highest Peak (Mt. Jade, Taiwan). Sensors (Basel), 9 (9), 6604–6612.
• Dobrin, M.B., Savit, C.H., 1988. Introduction to Geophysical Prospecting: McGraw-Hill Book Company, 867 p.
• Geosoft Oasis Montaj (GOM) reference manual, 2008. Software for Earth Sciences, Geosoft INC, Toronto, Canada.
• Ghaib, F.A., Mohammad, R.J., Khan, Z.A., 1998. A reconnaissance gravity survey in the Sulaivany plain, N-Iraq. The Journal of Duhok University (Scientific and Academic), 1 (1): 6-20.
• Hafidh A.A., Matthew S., Youlin Chen, Robert B., Ghassan I., Hrvoje T., Bakir S., Borhan I., Dawood S., Robert A., Patrick J., Omar K., Aras M., Shaho A., Fadhil I., Rashid Z., Basoz A., Layla O., Nokhsha I., Nian H., Talal N., Ali A., Abdul-Karem A., Samira R., 2007. Seismic velocity modeling of north and northeast Iraq using receiver functions, 29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies.
• Hernandez, O., 2006. Tectonic analysis of northwestern South America from integrated satellite, airborne and surface potential field anomalies. Graduate School of Ohio State University, U.S.A, PhD thesis, 176 p.
• Hinze W.J., Aiken C., Brozena J., Coakley B., Dater D., Flanagan G., Forsberg R., Hildenbrand T., Keller G.R., Kellogg J., Kucks R., Li X., Mainville A., Morin R., Pilkington M., Plouff D., Ravat D., Roman D., Urrutia-Fucugauchi J., V´eronneau M., Webring M., Winester D., 2005. New standards for reducing gravity data, The North American gravity database. Geophysics, 70 (4), J25–J32.
• Janák, J., Vanícek, P., 2005. Mean free-air gravity anomalies in the mountains. Studia Geophysia et Geodaetica, 49, 31-42.
• Jassim, S.Z., Goff J.C., 2006. Phanerozoic development of the northern Arabian Plate, Geology of Iraq, 32-44.
• Leaman, D.E., 1998. The gravity terrain correction–practical considerations. Exploration Geophysics, 29, 476-471.
• Li, X., Götze, H.J., 2001. Ellipsoid, geoid, gravity, geodesy, and geophysics, Geophysics, 66, 1660-1668.
• Lockwood, A., 2004. Isostatic and Decompensative Gravity Anomalies over Western Australia. Australian Society of Exploration Geophysicists, Preview, 108, 22-23.
• Lowrie, W., 2007. Fundamentals of Geophysics. Cambridge University Press, Cambridge, UK, 354 p.
• Lynch, A. and King, R.A., 1983. A review of parameters affecting the accuracy and resolution of gravity surveys. Exploration Geophysics, 14: 131-142.
• Lyngsie, S.B., Thybo, H., Rasmussen, T.M., 2006. Regional geological and tectonic structures of the North Sea area from potential field modeling. Tectonophysics 413, 147–170.
• Mogren, S., Al-Amri, A.S., Al-Damegh, K., Fairhead, D., Jassim, S., Algamdi, A., 2007. Sub-surface geometry of Ar Rika and Ruwah faults from Gravity and Magnetic Surveys, King Saud University, College of Sciences, Geology & Geophysics Department, Riyadh, Saudi Arabia.
• Mutib M., 1980. Geophysical investigation around Demir Dagh area. Mosul University, Iraq, MSc. thesis, (unpublished).
• Nabighian, M.E., Ander, V.J., Graunch, R.O., Hansen, T.R., Lafehr, Y. Pearson, W.C., Peirce, J.W., Phillips, J.D., Ruder, M.E., 2005. Historical Development of the Gravity Method in Exploration. Geophysics, 70 (6), 63-89.
• Roy, K.K., 2008. Potential Theory in Applied Geophysics. Springer-Verlag Berlin Heidelberg, 651 p.
• Sayyab, A., Valek, R., 1968. Pattern and general properties of the gravity field of Iraq. 23rd International Geological Congress, Czechoslovakia, 5, 129-142.
• Zeng, H., Xu, D., Tan, H., 2007. A model study for estimating optimum upward continuation height for gravity separation with application to a Bouguer gravity anomaly over a mineral deposit, Jilin province, Northeast China. Geophysics, 72, 145–150.