Gravity and Magnetic Survey Off Vancouver Island, 1975

1977 ◽  
Author(s):  
R P Riddihough ◽  
D L Tiffin
Keyword(s):  
Vancouver Island ◽  
Magnetic Survey ◽  
Gravity And Magnetic

Geologic interpretation of magnetic and gravity anomalies in the Strait of Juan de Fuca, U.S.–Canada

1977 ◽  
Vol 14 (2) ◽  
pp. 223-238 ◽  
Author(s):  
N. S. MacLeod ◽  
D. L. Tiffin ◽  
P. D. Snavely Jr. ◽  
R. G. Currie
Keyword(s):  
Continental Shelf ◽  
Gravity Anomalies ◽  
Vancouver Island ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Olympic Peninsula ◽  
Basement Rocks ◽  
Gravity And Magnetic ◽  
Juan De Fuca ◽  
Magnetic And Gravity Anomalies

A gravity and magnetic survey of the Strait of Juan de Fuca and adjacent Pacific continental shelf was conducted to define the tectonic framework in this 20 to 35 km wide seaway and its relation to that of Vancouver Island and the Olympic Peninsula. The offshore extensions of large onshore faults are delineated by linear magnetic and gravity anomalies. One of these, the Leech River fault of southern Vancouver Island, marks the northern limit of oceanic-type basaltic basement present in western Washington and Oregon. This fault probably continues southeast-ward from Vancouver Island across the strait to near the northeastern coast of the Olympic Peninsula, and westward across the strait to the continental shelf off Cape Flattery. The Calawah fault, which extends northwestward from near Cape Flattery onto the Pacific shelf, terminates the Leech River fault. Northwest of the Leech River fault on the shelf, the Calawah fault probably is the contact between oceanic and continental crustal types. The gravity and magnetic data also indicate the location of folds, other faults, and areas of shallow basement rocks.

Gravity and Magnetic Survey in Southwestern Part of Cuddapah Basin, India and its Implication for Shallow Crustal Architecture and Mineralization

2019 ◽  
Vol 93 (4) ◽  
pp. 419-430 ◽  
Author(s):  
Shuva Shankha Ganguli ◽  
Satyaveer Singh ◽  
Niharika Das ◽  
Deepak Maurya ◽  
Sanjit Kumar Pal ◽  
...  
Keyword(s):  
Magnetic Survey ◽  
Cuddapah Basin ◽  
Southwestern Part ◽  
Gravity And Magnetic

Contribution of magnetic modeling to the discovery of a hidden massive sulfide body at Hajar, Morocco

Geophysics ◽  
1991 ◽  
Vol 56 (7) ◽  
pp. 983-991 ◽  
Author(s):  
A. Bellott ◽  
J. Corpel ◽  
R. Millon
Keyword(s):  
Gravity Data ◽  
Massive Sulfide ◽  
Magnetic Survey ◽  
Massive Sulfides ◽  
Magnetic Modeling ◽  
Gravity And Magnetic ◽  
Gravity Response ◽  
Modeling Techniques ◽  
Magnetic Model ◽  
D Model

The Hajar prospect is located in the Guemassa Paleozoic massif, about 30 km southwest of Marrakesh, Morocco. Visean volcano‐sedimentary formations are present in this massif and in the Jebilets massif north of Marrakesh. In these formations, syngenetic massive sulfides occur, and one of these bodies, Kettara in the Jebilets, has been partially mined. Using the Kettara magnetic anomaly to establish the magnetization parameters, we performed a preliminary interpretation of the Hajar anomaly. Our 2.5-D model determined the depth of the structure to be about 150 to 200 m below the surface. This relatively shallow depth was a decisive factor in siting a reconnaissance drillhole, which encountered massive sulfides between 158 and 276 m. After completing a systematic gravity and magnetic survey, 3-D magnetic modeling was attempted, constrained by the results of four drillholes. Now that more than 20 holes have been drilled, this magnetic model still conforms to the newly revealed geology. Unfortunately, it was not possible to extract useful information concerning the orebody from modeling and interpreting the gravity data. The gravity response is masked by disturbances such as faults and variations in depth and nature of the Visean basement. The discovery of the Hajar deposit shows that magnetic investigations, improved by pertinent modeling techniques, can be used at various stages of exploration to help recognize and define massive sulfide bodies.

A Discussion on volcanism and the structure of the Earth - Geophysical studies relating to the Tertiary volcanic structure of the British Isles

1972 ◽  
Vol 271 (1213) ◽  
pp. 209-215 ◽  
Keyword(s):  
Northern Ireland ◽  
Magnetic Survey ◽  
Volcanic Structure ◽  
Normal Faulting ◽  
The Earth ◽  
Gravity And Magnetic ◽  
Deep Crustal Structure ◽  
Igneous Activity ◽  
Survey Results ◽  
Time Variations

Gravity and magnetic survey results over the Scottish Tertiary districts are characterized by step, linear and circular anomalies relating to faulted basalts, dykes and intrusive centres. A few circular anomalies in areas offshore can be interpreted to define additional intrusive centres. Step anomalies observed in Northern Ireland indicate that normal faulting occurred after the period of igneous activity. Deep crustal structure is ill-determined; observations of anomalous magnetic time variations and enhanced heat flow appear to warrant continuation of these studies.

3D geophysical modeling of the Alberton-Mathinna section of the “Main Slide,” northeast Tasmania

2020 ◽  
Vol 8 (3) ◽  
pp. T525-T540
Author(s):  
Daniel Bombardieri ◽  
Mark Duffett ◽  
Andrew McNeill ◽  
Mike Vicary ◽  
Rod Paterson
Keyword(s):  
Cross Sections ◽  
3D Model ◽  
Physical Property ◽  
Magnetic Survey ◽  
Geophysical Modeling ◽  
New Synthesis ◽  
Gravity And Magnetic ◽  
Rock Physical Property ◽  
Geological Units ◽  
Fault Network

We have developed a high-resolution 3D model of the Alberton-Mathinna section of the “Main Slide,” northeast Tasmania. This geological model expresses a new synthesis based on mapping and structural interpretation on multiple cross sections. We have refined this model by 3D geophysical inversion constrained by gravity and magnetic survey data coupled with drilling and rock physical property databases. Our modeling incorporates statistically generated sensitivity characterization metrics into 3D model products that map confidence in the geometry of geological units at depth. The results include a granitoid surface that is considerably more detailed than earlier versions based on 2D modeling. Among the new features to emerge is a cupola 1.6 km below and slightly west of the Mathinna goldfield. At the Ringarooma United deposit located within the Alberton goldfield, we seethat the fault network underpinning the deposit was intruded by granite to a depth of approximately 400 m. Ore-forming solutions for both deposits have been interpreted as metamorphic in origin, but our results suggest the possibility of a role for magmatic fluids (i.e., granite related) in the gold-mineralizing system, particularly for the Ringarooma United deposit.

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