Correlation of Sedimentary Basins Across the North Atlantic as Obtained from Gravity and Magnetic Data, and Its Relation to the Early Evolution of the North Atlantic

1989 ◽  
Author(s):  
J. Verhoef ◽  
S.P. Srivastava
Keyword(s):  
North Atlantic ◽  
Sedimentary Basins ◽  
Early Evolution ◽  
Magnetic Data ◽  
The North ◽  
Gravity And Magnetic ◽  
The North Atlantic ◽  
Gravity And Magnetic Data

INVESTIGATION OF MAGNETIZATION AND DENSITY OF A NORTH ATLANTIC SEAMOUNT USING POISSON’S THEOREM

Geophysics ◽  
1971 ◽  
Vol 36 (5) ◽  
pp. 919-937 ◽  
Author(s):  
Lindrith Cordell ◽  
Patrick T. Taylor
Keyword(s):  
Physical Properties ◽  
North Atlantic ◽  
Remanent Magnetization ◽  
Fourier Transforms ◽  
Magnetic Data ◽  
Total Magnetization ◽  
The North ◽  
Gravity And Magnetic ◽  
Special Cases ◽  
The North Atlantic

The relationship between the gravitational and magnetic potentials caused by a uniform distribution of mass and magnetization may be used to obtain independent information about these physical properties. The general relationship in the frequency domain between the Fourier transforms of the gravity and magnetic anomaly fields is established through the Poisson theorem. The discrete Fourier transforms of the sampled continuous functions are used in an analysis which leads to a system of linear equations involving terms in density, magnetization, and calculated finite Fourier‐series coefficients. A least squares solution of the system yields the three components of the total magnetization vector divided by the density. From these results, the direction of total magnetization and the minimum of the Koenigsberger ratio Q can be determined uniquely. The remanent magnetization direction and certain other information can be derived for special cases in which the value of one or more of the physical property terms can be assigned. Accurate results were obtained in the analysis of data from a theoretical model. Analysis of gravity and magnetic data from the North Atlantic Gilliss seamount indicates the presence of a significant component of remanent magnetization and leads to derived physical properties which are in fairly close agreement with dredged sample data. The calculated direction of remanent magnetization indicates a paleomagnetic pole position in eastern Siberia, in general agreement with the predicted position for a Cretaceous source in the North Atlantic. The seamount example illustrates certain contingent problems to be considered in practical application of the method.

Bright spots, milligals, and gammas

Geophysics ◽  
1982 ◽  
Vol 47 (12) ◽  
pp. 1693-1705
Author(s):  
Alan O. Ramo ◽  
James W. Bradley
Keyword(s):  
Seismic Data ◽  
Magnetic Data ◽  
Amplitude Analysis ◽  
Seismic Amplitude ◽  
The North ◽  
Gravity And Magnetic ◽  
Amplitude Anomaly ◽  
North Edge ◽  
Gravity And Magnetic Data ◽  
Seismic Anomaly

Spatially discontinuous high‐amplitude seismic reflections were encountered in seismic data acquired in the early 1970s in northeast Louisiana and southwest Arkansas. Large acoustic impedance contrasts are known to result from gaseous hydrocarbon accumulations. However, amplitude anomalies may also result from large density and velocity contrasts which are geologically unrelated to hydrocarbon entrapment. A well drilled on the northeast Louisiana amplitude anomaly encountered 300 ft of rhyolite at a depth of 6170 ft. Subsequent gravity and total field magnetic profiles across the feature revealed the presence of 0.2 mgal and 17 gamma anomalies, respectively. The measured magnetic susceptibility of the rhyolite was 0.0035 emu and the measured density contrast was [Formula: see text]. Model studies based on the seismically determined areal extent of the anomaly and the measured thickness of rhyolite accounted for the observed gravity and magnetic anomalies. The southwest Arkansas amplitude anomaly was a sheet‐like reflection which terminated to the north and west within the survey area. Two north‐south gravity profiles exhibited a negative character over the sheet‐like reflector but did not exhibit a clear spatial correlation with the north limit of the seismic anomaly. Two north‐south magnetic profiles exhibited tenuous 4 gamma anomalies which appeared to be spatially correlated with the interpreted north edge of the seismic anomaly. A subsequent wildcat well encountered no igneous material but did penetrate 200 ft of salt at about 7500 ft. Reassessment of the gravity and magnetic data indicated that this seismic amplitude anomaly is not attributable to an intrasedimentary igneous source; it suggested a salt‐related 0.2 to 0.3 mgal minimum coextensive with the observed seismic amplitude anomaly. Present amplitude analysis technology would treat these seismic data with suspicion. However, gravity and magnetic data acquisition can provide a relatively inexpensive means for evaluation and verification of amplitude anomalies and thus should be an adjunct for land seismic exploration utilizing amplitude analysis.

scholarly journals The hidden sedimentary basin underneath the Quaternary volcanic unit in Bogor and Kendeng area

2021 ◽  
Vol 47 (2) ◽  
pp. 25-47
Author(s):  
Erlangga Septama ◽  
C. Prasetyadi ◽  
A Abdurrokhim ◽  
T. Setiawan ◽  
P.D. Wardaya ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Sediment Supply ◽  
Passive Margin ◽  
Magnetic Data ◽  
Rock Samples ◽  
Petroleum Systems ◽  
The North ◽  
Gravity And Magnetic ◽  
Gravity And Magnetic Data ◽  
East West

The Java Island is an active volcanic arc that experiences several volcanism episodes, which gradually changes from South to North from the Late Oligocene to Pleistocene, following the subduction of the Australian plates underneath the Eurasian plates. During the Eocene, the southern and northern part of Java was connected as one passive margin system with the sediment supply mainly comes from Sundaland in the north.  The compressional tectonics creates a flexural margin and a deep depression in the central axis of Java Island and acts as an ultimate deep-sea depocenter in the Neogene period. In contrast to the neighboring Northwest and Northeast Java Basins in the Northern edges of Java Island, the basin configuration in the East-West trending depression in median ranges of Java (from Bogor to Kendeng Troughs) are visually undetected by seismic due to the immense Quaternary volcanic eruption covers.Five focused window areas are selected for this study. A total of 1,893 Km sections, 584 rock samples, 1569 gravity and magnetic data, and 29 geochemical samples (rocks, oil, and gas samples) were acquired during the study. Geological fieldwork was focused on the stratigraphic unit composition and the observable features of deformation products from the outcrops. Due to the Paleogene deposit exposure scarcity in the Central-East Java area, the rock samples were also collected from the mud volcano ejected materials in the Sangiran Dome.The distinct subsurface configuration differences between Bogor and Kendeng Troughs are mainly in the tectonic basement involvement and the effect of the shortening on the formerly rift basin. Both Bogor and Kendeng Troughs are active petroleum systems that generate type II /III Kerogen typical of reduction zone organic material derived from transition to the shallow marine environment. The result suggests that these basins are secular from the neighboring basins with a native petroleum system specific to the palaeogeographical condition during the Paleogene to Neogene periods where the North Java systems (e.g., Northwest and Northeast Java Basin) was characterized by oxidized terrigenous type III Kerogen.

scholarly journals East Greenland and Faroe–Shetland sediment provenance and Palaeogene sand dispersal systems

2006 ◽  
Vol 10 ◽  
pp. 29-32 ◽  
Author(s):  
Michael Larsen ◽  
Christian Knudsen ◽  
Dirk Frei ◽  
Martina Frei ◽  
Thomas Rasmussen ◽  
...  
Keyword(s):  
North Atlantic ◽  
Sedimentary Basins ◽  
Sediment Provenance ◽  
Basin Evolution ◽  
Faroe Islands ◽  
Provenance Analysis ◽  
East Greenland ◽  
The North ◽  
Sedimentary Succession ◽  
The North Atlantic

The sedimentation and basin evolution of the Kangerlussuaq Basin, southern East Greenland has gained renewed interest with the licensing rounds offshore the Faroe Islands in 2000 and 2005, as it forms an important analogy to the Faroese geological setting. The Faroes frontier area is in part covered by basalts and is a high-risk area with poorly known plays and sedimentary basins. It is therefore essential to obtain as much information as possible on the evolution of sedimentary basins on the rifted volcanic margins closest to the Faroese Islands margin. Plate reconstructions of the North Atlantic region indicate the former close proximity of East Greenland to the Faroe Islands region (Fig. 1), and the Kangerlussuaq Basin thus constitutes the most important field analogue with respect to stratigraphy, major unconformities and basin evolution. The study of the sedimentary succession in the Kangerlussuaq Basin, and the provenance of the sandstones in particular, will provide constraints on exploration models and may help to predict the distribution of potential reservoir sandstones in the Faroese offshore basins, and eventually lead to development of play types that are new to this frontier region.This paper presents the main conclusions from two research projects: Stratigraphy of the pre-basaltic sedimentary succession of the Kangerlussuaq Basin -Volcanic basin of the North Atlantic and An innovative sedimentary provenance analysis, jointly undertaken by the Geological Survey of Denmark and Greenland (GEUS) and CASP (formerly Cambridge Arctic Shelf Programme). Both projects were initiated in October 2002 and concluded in September 2005. They form part of Future Exploration Issues Programme of the Faroese Continental Shelf (SINDRI programme), established by the Faroese Ministry of Petroleum and financed by the partners of the Sindri Group (see Acknowledgements).

The extent of igneous rocks of the South China Sea based on the correlational analyses of gravity and magnetic data

2020 ◽  
Author(s):  
Min Yang ◽  
Wanyin Wang ◽  
Xiaolin Ji ◽  
Tao Ma ◽  
Jie Ma ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Igneous Rocks ◽  
Magnetic Data ◽  
The South ◽  
China Sea ◽  
The North ◽  
Gravity And Magnetic ◽  
Gravity And Magnetic Data

<p>The South China Sea is the biggest conjugate marginal sea in the West Pacific Ocean, which is influenced by the Eurasian plate, the Pacific plate, and the Indo-Australian plate. There have developed continental tectonic margins with different characters after experiencing subduction, collision, strike-slip and so on since the Mesozoic and Cenozoic (Yao et al., 2004; Zhang et al., 2014). However, the igneous rock can be regarded as a recorder to reveal some information of evolution and deep geodynamics of the South China Sea, which helps us to improve understanding of the continental rifting, the seafloor spreading, the formation of deep water basins and the process of hydrocarbon accumulation(Zhang et al., 2016).<br>The igneous rocks are studied by multiple types of data that are magnetic data, seismic profiles, and drilling data in the previous studies. Hence, there are bunch of research results about the igneous rocks that contain the reason and time of formation, the distribution of space, the period of eruption in the north of the South China Sea because of the abundant datasets (Zou et al., 1993,1995; Zhou et al., Yan and Liu, 2005; Xu et al., 2013; Zhang et al., 2013; Zhang et al., 2014; Zhang et al., 2015; Zhang et al., 2016), in addition, the Pearl River Mouth Basin is the most famous one among all of the basins in the South China Sea. However, the researchs related to the south of the South China Sea where are the deep-sea are far less knowledgeable about the distribution of the igneous rocks than the north because of the limitation of datasets that are poor quality and less quantity (Yao et al., 2004; Li et al., 2010; Hui et al., 2016), which lead to the less researches with respect to the big area of the South China Sea.<br>The followings can be concluded from the previous studies. The northern and continental margin of the South China Sea are distributed by Cenozoic extrusive rocks with high susceptibility and low density and Yanshanian intrusive rocks with low susceptibility and density (Hao et al., 2009; Lu et al., 2011; Hui et al., 2016), the Central Sub-basin is covered by Cenozoic extrusive rocks (Yan and Liu, 2005; Hui et al., 2016), however, there are few distributions of the Yanshanian intrusive rocks in the Southern South China Sea (Zhang et al., 2015; Hui et al., 2016). In this study, a new method, the fusion of gravity and magnetic data, is applied to detect the distribution of the igneous rocks in order to provide more geophysical data in the South China Sea.</p>

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