scholarly journals Principal facts for gravity data collected in the northern Susitna Basin area, southcentral Alaska

10.14509/7186 ◽  
2005 ◽  
Author(s):  
J. F. Meyer
2019 ◽  
Vol 42 (2) ◽  
pp. 65-71
Author(s):  
Tatang Padmawidjaja ◽  
Yusuf Iskandar ◽  
Andy Setyo Wibowo ◽  
Eko Budi Lelono

The Geological Survey Center has conducted a seismic survey in the southern Natuna Sea region to obtain geological information below relating to the potential energy resources of the area. The area research is located in the western part and outside the Singkawang Basin area (BG, 2008), which is separated by a Metamorf ridge. 2D seismic survey results show 3 different rock units, namely shallow marine sedimentary rocks, tertiary sedimentary rocks and pre-Tertiary sedimentary rocks, with pre-Tertiary sediment depths of less than 2000 ms. Interpretation of seismic data shows the pattern of graben structures that form sub-basins. strong refl ectors seen in seismic record can distinguish pre-rift, syn-rift and post-rift deposits. There are 2 wells, namely Datuk 1X and Ambu 1X. Datuk 1X has a depth of 1187 meters, and The Ambu 1X has a depth of 880 meters that is crossed by a seismic line. Both drilling has obtained Tertiary aged sandstone that covers pre-Tertiary bedrock.Gravity anomaly data in the seismic region shows anomaly values between 10 to 54 mgal which form the anomaly ridge and basinThe ridge anomaly extends as an anticline, while the anomaly basin also rises to form a syncline. Sincline and anticline trending southwest - southeast, with widening and narrowing patterns.Based on its geological model, the depth of the sediment is relatively shallow between 1500 to 2000 meters. While the integration between seismic, gravity and geomagnetic data shows the discovery of new basins that have never been described before.Finally, the integration of seismic and gravity data succeed discovers a new basin which has never been delineated before. In addition, it shows the continuity of the regional geological structure spanning from the studied area to the West Natuna Basin which is well known to be rich in hydrocarbon potential.


Geophysics ◽  
1990 ◽  
Vol 55 (3) ◽  
pp. 327-335 ◽  
Author(s):  
D. Chenot ◽  
N. Debeglia

Depth‐mapping inversion of gravity or magnetic fields generally assumes that anomalies originate from a main density or magnetization contrast interface. This particular inversion takes into account inhomogeneous density or magnetization distributions reflecting sediment compaction and basement heterogeneities: above the interface, the density can be approximated by an exponential function, and below it, an intrabasement contrast map can be used. The inversion also integrates local depth constraints from wells or seismic data, as well as general constraints set on the geometry and the contrast of the interface. After field transformations, spectral analysis and constraints help to define a starting model characterized mainly by the interface mean depth and the mean parameter contrast between the two media. The depth adjustment is completed iteratively under constraints using a space‐domain formulation derived from the Bouguer‐slab approximation. The interface model effect is computed in the wavenumber domain. A model data example shows the accuracy of the inversion and illustrates the role of the constraints. In a field example of a basin area where constraints can be derived from numerous well data, successive inversions of gravity data result in an isodepth map of the basement. The compatibility of the map with local depth constraints from wells is obtained by taking into account density heterogeneities related to known lithologic variations in the basement.


2000 ◽  
Author(s):  
Cindy L. Gillespie ◽  
V.J.S. Grauch ◽  
Kim Oshetski ◽  
Gordon R. Keller
Keyword(s):  

2013 ◽  
Vol 63 (2) ◽  
pp. 271-281 ◽  
Author(s):  
Magdalena Kokowska-Pawłowska ◽  
Jacek Nowak

Abstract Kokowska-Pawłowska, M. and Nowak, J. 2013. Phosphorus minerals in tonstein; coal seam 405 at Sośnica- Makoszowy coal mine, Upper Silesia, southern Poland. Acta Geologica Polonica, 63 (2), 271-281. Warszawa. The paper presents results of research on tonstein, which constitutes an interburden in coal seam 405 at the Sośnica- Makoszowy coal mine, Makoszowy field (mining level 600 m), Upper Silesia, southern Poland. The mineral and chemical compositions of the tonstein differ from the typical compositions described earlier for tonsteins from Upper Silesia Coal Basin area. Additionally, minerals present in the tonsteins include kaolinite, quartz, kaolinitised biotite and feldspars. The presence of the phosphatic minerals apatite and goyazite has been recognized. The presence of gorceixite and crandallite is also possible. The contents of CaO (5.66 wt%) and P2O5 (6.2 wt%) are remarkably high. Analysis of selected trace elements demonstrated high contents of Sr (4937 ppm) and Ba (4300 ppm), related to the phosphatic minerals. On the basis of mineral composition the tonstein has been identified as a crystalline tonstein, transitional to a multiplied one.


Think India ◽  
2019 ◽  
Vol 22 (2) ◽  
pp. 296-304
Author(s):  
Biplab Tripathy ◽  
Tanmoy Mondal

India is a subcontinent, there huge no of people lived in river basin area. In India there more or less 80% of people directly or indirectly depend on River. Ganga, Brahamputra in North and North East and Mahanadi, Govabori, Krishna, Kaveri, Narmoda, Tapti, Mahi in South are the major river basin in India. There each year due to flood and high tide lots of people are suffered in river basin region in India. These problems destroy the socio economic peace and hope of the people in river basin. There peoples are continuously suffered by lots of difficulties in sort or in long term basis. Few basin regions are always in high alert at the time of monsoon seasons. Sometime due to over migration from basin area, it becomes empty and creates an ultimate loss of resources in India and causes a dis-balance situation in this area.


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