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The AAPG/Datapages Combined Publications Database

Oklahoma City Geological Society

Abstract


The Shale Shaker Digest II, Volumes VI-VIII (1955-1958)
Pages 188-188

Component Dip Nomogram

John Bemrose

ABSTRACT

The determination of the Previous HitmagnitudeNext Hit and direction of component dip from the Previous HitmagnitudeNext Hit and direction of the true dip by means of a circular nomogram.

When the Previous HitmagnitudeNext Hit and direction of a true dip of a plane are given the Previous HitmagnitudeTop of the component dip in a vertical plane in any direction may be very conveniently solved for routine work by means of a circular nomogram.

Let (alpha.gif (53 bytes)) be the true dip and (alpha.gif (53 bytes)prime1.gif (824 bytes)) the component of the true dip in a direction which makes an angle (o) with the direction of the true dip; then it is well known that:

0188_e1.jpg (1,786 bytes)      (1)

or,

0188_e2.jpg (2,043 bytes)      (2)

or, if (m) is a scale factor the constructional determinant for the nomogram may be written:

0188_e3.jpg (8,713 bytes)      (3)

Let:

0188_e4.jpg (2,209 bytes)      (4)

and

0188_e5.jpg (2,576 bytes)      (5)

then, eliminating (Tan alpha.gif (53 bytes)) between these two equations, it is found that:

0188_e6.jpg (1,707 bytes)      (6)

which is the equation to a circle passing through the origin whose radius is equal to (m). Thus, the scale for the true dip (alpha.gif (53 bytes)) is therefore the upper half of the circumference of a circle of radius (m); similarly, the scale for the direction (O) is the lower half of the circumference of the same circle, and the scale for the component dip (alpha.gif (53 bytes)prime1.gif (824 bytes)) is the diameter of this circle separating the (alpha.gif (53 bytes)) and (O) scales.

The completed nomogram is shown in , together with an example from which it is seen that by a straight line alignment of the scales that when (O) = 36 degrees and (alpha.gif (53 bytes)) = 30 degrees, the component dip (alpha.gif (53 bytes)prime1.gif (824 bytes)) = 25 degrees.

COMPONENT DIP NOMOGRAM

End_of_Record - Last_Page 188-------

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