Stereographic Projection
spherical projection 1 1 O great circle small circle pole Z = zenith A stereographic projection O primitive circle C D S C lower hemisphere = nadia 1
Z θ 3 P O P P r tan θ 3 P Wulff's stereographic net, Wulff net meridional stereographic net, meridian net 4 stereonet 4
Z 5 O C P' ZP' P' O = r tan Z= sec P 5 6 Z r OMC R OC O M' C = sec C C M= P tan r 7 OC = tan OC = sec M 6 7 bowl 3
8 8 30 E,40 E 9 (a) (c) 30 40 9 90 40 40 40 0 90 S4 E 30 10 S4 E 4 30 -S45 W 10 4
36 W(31 ) 11 46 11 50 E50 SE 80 E 1 31 (1)30,45 W (),14 E 80 E 13 (1)() 1 P1:70 W0 S,P:50 E60 S 14 S38 W 19 P3 P1,P P3 p1,p 13 5
15 p 5 p 1 P 1 44 p 3 5 P 3 p 1 19 38 14 15 59 E 46 1 P1(40 E40 ) 15 P1 p1 1 p1 P1 1 1 P1 44 R 16 45 45 p' P 16 R P' p 30 W40 E 30 7 W0 16 7 p 30 30 R 17 R R P p R' p' R' p' p" R p" P 17 P(83 E5 S) R(30,4 E) 80 18 R R p R R p' R P P' 6
p 80 R 80 p ' p R' pr=41 R' R 41 41 35 R p' Unfolding 30 19 W60 E 6 p' 19 18 unfolding 19 P P' 19 P P' 5 ' 55 R 19 p P' p" 30 65 65 ' p' P " p' p p" P' ' P " 19 0 P O 1 0 P 7
P 4 P P 5 3 P P 3 P 3 34 P 4 P P 3 P 3 345 P 1 P 4 P 3 G 13 P 4 P 5 G 134 G 1345 P 3 1 3 P P P Z O r P equal-area projection ambert projection P' 3 3 P=P' P' P P' P'=r sin P'= r sin 8
Z 4 5 X ' m = lim 0 X X =A = r X ' = A' ' = A + = rsin -rsin + = r sin sin + sin sin m = lim 0 d = sin = cos d Y ' p = lim Y Y = H φ 0 φ = r φ sin Y ' = ' φ = r φ sin sin 1 p = lim = φ 0 sin cos S = m p = 1 O φ O H H Z φ φ φ X ' Y X Y' 4 (1) φ A ' A' Y ' Y' 5 () m<1 p>1 W. Schmidt(195) 6 Schmidt's net equal-area net 9 6
7 point diagram 7 types of concentration 8 (a maximum) linear preferred orientation planar preferred orientation (a girdle) (girdle axis) crossed girdle 8 10
(a small circle, "cleft" girdle) girdle axis maxima density contours contoured diagram point counter Schmidegg 1/10 counting circle 9 counting 9 9a 9b counting 1 6 3 4 5 11
Schmidt 400 30a 1/0 30 30a 30b (free contour method) 00 400 31 31 Mellis 150 3 1
3 ( diagram) S-pole diagram cylindrical fold ac 33 open fold 33 34 13
tight fold chevron fold 34 superposed fold -diagram 35a n n(n-1)/ 35b 35c 35d 35 14
36 40 E1 SE 75 W3 80 E3 S 35 W40 SW 1 W45 W 76 S 0 W 76 SE 44 W 86 S 50 W55 SW T T 4 T 5 76 T 3 T 1 40 36 37 37 ; 76 W 30 W65 E ; 48 1 W85 E ; 45 53 E85 SE ; 34 SW 45 E90 ; 44 SW 46 W18 SW ; 36 W 38 15
owe(1946) 38a Cruden(1971) 38b owe flexure folding 39 shear folding 39 40 A A C 90 A A C 90 40 16
75 E 50 E A 66 E50 S W40 W oulder Creek 0 E30 E 30 W40 W 40 E 4 5 W3 E 70 5 E 50 1 3 133 43 15 50 155 45 130 45 130 58 148 63 10 5 14 53 13 65 14 60 17
95 85 85 70 300 63 335 80 30 83 90 76 9 74 330 88 15 50 35 E50 SE 75 W31 5 W70 E 78 W 17 W64 W 37 W49 E 41 W47 E 5 W54 W W74 W 14 W75 W 6 W56 W 43 W39 E 3 E3 W 11 W33 W 38 W47 W 1 W44 W 4 W75 E 18 E41 W 35 W9 E 4 W6 E 50 W49 E 1 W37 W 60 W3 10 W67 W 35 E0 W 16 W57 W 4 W84 E 8 W55 E 39 W60 W 68 E5 40 W30 E 3 W48 W 15 W54 W 5 W49 W 5 W80 E 10 W68 E 14 W50 W 5 E30 W 1 E4 W 37 W68 W 4 W58 W 51 W41 3 W66 W 8 W75 W 33 W44 E 35 W58 E 45 W50 E 17 W43 E 44 W43 E 19 W54 W 9 W86 E (1) () (3) (4) 80 W30 (0 W) 50 E80 (30 W) (46 W) 5 E10 E(40 S) 7 E0 S(80 W) Drill Hole Data 1.8m 60 60m (0 E 30 ) 33.6m 45 1 8 S37 W 61 S1 E 3 50 S7 E 17 34 30 Ragan, M. D. (1973): Structural Geology -- An Introduction to Geometrical Techniques. nd ed. John Wiley & Sons. Inc. 08pp. Turner, F. J. & Weiss,. E. (1963): Structural Analysis of Metamorphic Tectonites. McGraw-Hill ook Co. 545pp. 18
19