1. Folds form due to compressional forces that cause originally flat rock layers to bend. They vary in size from microscopic to mountain-scale. 2. Studying folds provides important information about the nature of deformation, tectonic stresses, and orientations of forces that acted in the past. Folds also have economic significance as they can trap hydrocarbons and concentrate valuable minerals. 3. Folds have characteristic geometric features like hinge lines, axial planes, limbs, and inflection points. Their symmetry, wavelength, amplitude, and orientation provide clues about the tectonic forces that caused folding. Understanding folds requires knowledge of the overall tectonic environment in which they formed.

1. Folds and Folding
ً‫الثان‬ ‫الكورس‬ ‫محاضرات‬/ً‫الدراس‬ ‫للعام‬ ‫الثالثة‬ ‫المرحلة‬2017--2016
1

2. ‫الطٌات‬Folds
‫مختلف‬ ً‫وف‬ ‫الصخور‬ ‫انواع‬ ‫مختلف‬ ً‫ف‬ ‫تتكون‬ ً‫وه‬ ‫لالنتباه‬ ً‫ا‬‫جلب‬ ‫واكثرها‬ ‫انتشارا‬ ‫الثانوٌة‬ ‫الجٌولوجٌة‬ ‫التراكٌب‬ ‫اكثر‬ ‫من‬ ‫الطٌات‬ ‫عد‬ُ‫ت‬
‫االعماق‬‫التكتونٌة‬ ‫والبٌئات‬.‫بكثٌر‬ ‫سابق‬ ‫وقت‬ ً‫ف‬ ‫وتشخٌصها‬ ‫اكتشافها‬ ‫تم‬ ‫فقد‬ ‫ولذلك‬‫قبل‬‫ذاته‬ ‫بحد‬ ‫قائم‬ ‫كعلم‬ ‫االرض‬ ‫علم‬ ‫ٌظهر‬ ‫ان‬.
‫الزمن‬ ‫عبر‬ ‫والطٌات‬ ً‫الط‬ ‫مفهوم‬ ‫تطور‬ ‫وقد‬‫اال‬‫ان‬ً‫الماض‬ ‫القرن‬ ‫خمسٌنٌات‬ ً‫ف‬ ‫اسسها‬ ‫وضعت‬ ‫الحالٌة‬ ‫المفاهٌم‬.
‫الطٌات‬ ‫هندسٌة‬ ‫ان‬ ‫اذ‬ ً‫االقلٌم‬ ‫او‬ ً‫المحل‬ ‫التشوه‬ ‫تارٌخ‬ ‫على‬ ‫مهمة‬ ‫نافذة‬ ‫تمثل‬ ‫المالحظة‬ ‫مقاٌٌس‬ ‫مختلف‬ ‫على‬ ‫الطٌات‬ ‫دراسة‬ ‫ان‬
‫كانت‬ ‫سواء‬ ‫الكبٌرة‬ ‫االقتصادٌة‬ ‫اهمٌتها‬ ‫الى‬ ‫اضافة‬ ً‫التكتون‬ ‫والوضع‬ ‫الجهد‬ ‫واتجاهات‬ ‫التشوه‬ ‫طبٌعة‬ ‫عن‬ ‫مهمة‬ ‫معلومات‬ ‫تعكس‬
‫اقتصادٌة‬ ‫لمعادن‬ ‫تجمع‬ ‫او‬ ‫للهاٌدروكاربونات‬ ‫مصائد‬.
2
‫تكتونٌة‬ ‫قوة‬ ‫تاثٌر‬ ‫عن‬ ‫الناتجة‬ ‫االنواع‬ ‫تشمل‬ ‫المحاضرة‬ ‫هذه‬ ً‫ف‬ ‫بصددها‬ ‫نحن‬ ً‫الت‬ ‫الطٌات‬ ‫ان‬tectonic force‫التفاعل‬ ‫بسبب‬ ‫تنشأ‬
ً‫الحرك‬‫التكونٌة‬ ‫االطباق‬ ‫بٌن‬.‫ط‬ ‫مثل‬ ‫مختلفة‬ ‫قوى‬ ‫تاثٌر‬ ‫وتحت‬ ‫تكتونٌة‬ ‫غٌر‬ ‫قوة‬ ‫عن‬ ‫تنشا‬ ‫الطٌات‬ ‫من‬ ‫انواع‬ ‫ان‬ ‫اذ‬ٌ‫االنزالق‬ ‫ات‬
‫الترسٌب‬ ‫اثناء‬ ‫الرسوبٌة‬ ‫الصخرٌة‬ ‫للطبقات‬ ً‫التفاضل‬ ‫التراص‬ ‫بفعل‬ ‫او‬ ‫الجلٌدٌة‬ ‫الثالجٌات‬ ‫ثقل‬ ‫او‬ ‫االرضٌة‬ ‫الجاذبٌة‬ ‫قوى‬ ‫بفعل‬ ً‫الجذب‬
‫التصلب‬ ‫وقبل‬prelithfication.‫وغٌرها‬.
‫ن‬ ‫ان‬ ‫وٌجب‬‫ذ‬‫االستعانة‬ ‫ٌمكننا‬ ‫الحالة‬ ‫هذه‬ ً‫وف‬ ‫تحتة‬ ‫مطمورة‬ ‫انها‬ ‫اي‬ ‫االرض‬ ‫سطح‬ ‫على‬ ‫واضحة‬ ‫التكون‬ ‫قد‬ ‫الطٌات‬ ‫من‬ ‫كبٌر‬ ‫قسم‬ ‫ان‬ ‫كر‬
‫النفط‬ ‫حقول‬ ً‫ف‬ ‫وخاصة‬ ‫االبار‬ ‫حفر‬ ‫من‬ ‫علٌها‬ ‫نحصل‬ ‫قد‬ ً‫ات‬ ‫والمعلومات‬ ‫الجٌوفٌزٌائٌة‬ ‫باالجهزة‬.

3. • Perhaps more than any other geologic structure, folds really need to be
studied in a tectonic context.
• Folding can occur for so many different reasons that it is very nearly
impossible to understand how they occur without knowing the general tectonic
environment in which they form.
• Even with this knowledge, folds can be very difficult to understand...
Folds - Plate Tectonic Considerations
3

4. Description of folds
The term fold is: used flat and planar surfaces such as sedimentary
beds become bent or curved as a result of plastic (i.e. permanent)
and ductile deformation.
Folds in rocks vary in size from microscopic crinkles to mountain-
size folds.
A set of folds distributed on a regional scale constitutes a fold belt.
Fold belts are typically associated with convergent plate
boundaries and directed compressive stress.
4

5. Concentration of valuable minerals
in the hinges of the fold
Why Study Folds ?
-Hydrocarbon traps.( Folds can trap oil
and natural gas.)
-
5

6. Scale types of Folds
Folds can present in all
scales
 microscopic (require
magnification)
 mesoscopic (specimen and
outcrop size)
 macroscopic (larger scale)
6

7. 7

8. and volcanic rocksIn sedimentary rocks
Thrust Fault
Fold
Folds may complied with other structural types
(Thrust Fault)
8

9. Attitude of Beds
Attitude refer to the three-dimensional orientation of some geological feature,
such as bed, a joint, or a fold.
The attitude of planar features such as beds or joints is defined by their strike and
dip.
Strike: is the direction of the line that is formed by the intersection of the plane of the
rock bed with a horizontal surface.
Dip: is the direction in which the steepest angle is formed between the plane of the rock
bed and the horizontal surface.
9

10. Folds
Antiform Fold: fold that is convex upward, or Anticline fold that has older rocks in the center.
anticlines are folds where the originally horizontal strata has been folded upward, and the two
limbs of the fold dip away from the hinge of the fold.
Synform Fold: fold that is convex downward, in the simplest syncline the two limbs dip toward
each other. The term has been extended to any fold where younger rocks are in the center Parts
of Fold.
Parts of folds
Crest and Crestal plane: The crest of the fold is the highest point of the fold surface or the hinge
of fold. The plane connecting all the crests is called crestal plane.
Trough and Trough plane: The trough is the lowest points of the fold. The plane connecting such
points may be called the trough plane.
Hinge Point: point of maximum curvature.(If the hinge is sharp, that point is called the hinge
point otherwise it is called a hinge zone.)
Hinge line: The line connecting the points of maximum curvature of the bedding planes in a fold
. Folds with a straight hinge line are called cylindrical folds.it may be horizontal, inclined, or
vertical.it is defined by orientation and position.
Axial plane: is the surface connecting the successive hinges of a folded strata. also it is the
plane or surface that divides the fold as symmetrically as possible. The axial plane may be
vertical, horizontal, or inclined.the attitude of A.p. is defibed by strike and dip10

11. Axis: fold axis is a line which lies parallel to the hinge line and marks the intersection of the
axial plane with the hinge zone.
Limbs or Flanks: A limb extends from the axial plane in one fold to axial plane in the next.
or it is that portion of curved surface between the hinge point and inflection point.
Inflection Point: point where curve changes from concave to convex. (if the transition
from concave to convex involves a straight segment, there will be no inflection point ;then
is arbitrarily taken to be the midpoint.)
Inflection lines: Lines connecting points of zero curvature.
Median Surface: Surface passing through the inflection points of a single folded layer
Wavelength: the line connecting three inflection points. Or is the distance from one
anticlinal hinge to the next anticlinal hinge
Amplitude: Half the height of the structure measured from crest to trough. or the height
between the crest and median surface.
Enveloping Surface: imaginary plane that is tangential to the hinge zones of series of small
folds.it contains all antiformal or synforma hinges.
Interlimb Angle: the minimum angle between the limbs as measured in the profile plane.
We assume that the limbs are relatively planar or we use the tangent at the inflection
points.11

12. limbs dip away from eachcenter.tworocks in theupward,older:fold that is convexAnticline
other.
limbs dip toward eachcenter.two: fold that is convex downward. younger rocks in theSyncline
other.
12

13. Fold Anatomy (axial plane, fold axis, limbs and
inflection point)
inflection point
Hinge point
line
Fold axis
• Fold axis (not a physical line) cannot be marked on the folded surface13

14. A few of the different atittudes assumed by axial
planes and hings of fold.
axial plane is shaded in each diagram.
Is hinge of fold.aa′
Axial Plane
The attitude of axial plane is defined
by its strike and dip.
14

15. and Non-Cylindrical Folds
A fold axis is a geometric (imaginary) straight line which when moved parallel to itself through
space generates the shape of the fold.
Non-cylindrical folds (with curved hinge lines) do not have fold axes.
and for the purpose of detailed structural analysis (for example, stereographic
representation), it is necessary to subdivide them into several cylindrical folds, each with a
relatively short, nearly straight hinge line.
Cylindrical Folds
Cylindrical fold: fold with straight hinge line parallel to fold axis.
15

16. Crestal plane Axial plane
Parts of a fold .AP, axial plane; a′b ,limb of a fold; c, crest on one fold; c′,crest on another bed;
cc′ crestal plane; t, trough on one bed; t′ trough on another bed; tt′, trough plane.
Although in many instances the hinge is at the highest part of the fold, as in fig A,
this is not necessarily the case, as In fig B,C .
C
16

17. The distinction between the crest and hinge is significant in accumulation ogf gas and petrolum,
because the trapping of such material is controlled by the crest and crestal plane rather than by
hinge and axial plane.
HING
CREST
CRESTHING
17

18. In general,fold hinge lines undulate,and these changes in orientation give rise to special structural
forms.
The high points in crest lines are referred to as culminations and the low
points in trough lines are depressions.
18

19. ‫الداخلٌة‬ ‫الزاوٌة‬angleInterlimb:‫الزاوٌة‬ ً‫ه‬ً‫جناح‬ ‫امتداد‬ ‫بٌن‬ ‫المحصورة‬ ‫الداخلٌة‬
‫الطٌة‬‫مقٌاس‬ ً‫وه‬ً‫الط‬ ‫الحكام‬tightness of the fold‫االنضعاط‬ ‫شدة‬ ‫تعكس‬ ً‫والت‬
intensity of compression
Interlimb angle
19

20. Inflection point
Interlimb angle
The wavelength of folds is the distance from one anticlinal hinge to
the next anticlinal hinge. or the distance jointing 3 inflection points
The amplitude of folds half the height of the structure measured
from crest to trough or the distance between crest and median
surface. .
Wavelength Amplitude
ً‫الموج‬ ‫الطول‬
‫للطٌة‬ ‫والسعة‬
20

21. Folds Symmetry
1-vertical axial plane or upright.
2-Axial plane bisect the interlimb angle.
3-Equal length and dip angle of fold limbs.
4- A horizontal median surface and lie in the
midpoints between parallel enveloping
surfaces.
Condition of Symmetrical Folds
otherwise the is Assymetrical
A.P
A.P
envelop surface
Median surface
‫االحاطة‬ ‫سطح‬enveloping surface
Inflection Points
Interlimb angle
Symmetrical Anticline
Symmetrical Syncline
21

22. ‫االتكاء‬VergenceAsymmetry and
In symmetrical folds vergence is not a property. However, small folds on the limbs of
symmetrical fold may exhibit vergence.
Study of vergence may be useful in working out the overall direction of tectonic
transport of all structures in an area and help to fix an observer’s location on large fold..
tectonic transport
The direction of apparent movement of the upper, long limb with respect to the shorter
limb of an asymmetric fold is called the vergence. In other word, vergence is simply the sense
of asymmetry.
If the axial plane is not a plane of symmetry, the limbs have unequal lengths and
one limb dips more steeply than the other: the folds are asymmetric. Their leaning
direction suggests a relative sense of movement, termed the apparent vergence.
22

23. ‫الصحيح‬ ‫العرضي‬ ‫المقطع‬true profile‫الطيات‬ ‫انواع‬ ‫وصف‬ ‫في‬ ‫اعتمادة‬ ‫يتم‬
The profile is a reference plane used to describe and measure all geometrical characteristics of
the fold: symmetry, height or amplitude, wavelength, tightness, roundness. Indeed, these
aspects vary with the angular relationship between any section plane and the folded surface.
Profile of folds
23

24. ‫الطٌات‬ ‫انواع‬FOLDS TYPE
‫تشاهد‬ ‫قد‬ ً‫الت‬ ‫الطٌات‬ ‫معظم‬ ً‫تغط‬ ‫الطٌات‬ ‫من‬ ‫التالٌة‬ ‫االنواع‬ ‫ان‬
‫العرضٌة‬ ‫المقاطع‬ ‫وكذلك‬ ‫الحقل‬ ً‫ف‬Cross Section‫المرسومة‬
‫الجٌولوجٌة‬ ‫الخرائط‬ ‫من‬.
‫الطٌة‬ ‫محور‬ ‫على‬ ‫العمودٌة‬ ‫المقاطع‬ ‫تلك‬ ‫العرضٌة‬ ‫بالمقاطع‬ ‫ٌقصد‬
‫المستوي‬ ‫على‬ ‫عمودٌة‬ ‫او‬ ‫للطٌة‬ ‫المؤلفة‬ ‫الطبقات‬ ‫مضرب‬ ‫او‬
‫المحوري‬)
‫على‬ ‫باالعتماد‬ ‫االنواع‬ ‫هذه‬ ‫خصت‬ُ‫ش‬ ‫وقد‬
Based on:
‫توجٌة‬‫المستوي‬‫المحوري‬Orientation of the Axial plane
‫الطٌة‬ ‫اجنحة‬ ‫مٌل‬Tilt (or Dip) of the Fold limbs
24

25. 1-‫المحدبة‬ ‫الطٌة‬Anticline
2-‫المقعرة‬ ‫الطٌة‬Syncline
3-‫المتكئة‬ ‫الطٌة‬Overturned Fold
4-‫المضطجعة‬ ‫الطٌة‬Recumbent Fold
5-‫المٌل‬ ‫متساوٌة‬ ‫الطٌة‬Isoclinal Fold
6-‫الصندوقٌة‬ ‫الطٌة‬Box Fold
‫الطٌات‬ ‫انواع‬
7-‫الطٌة‬‫المسننة‬(‫اوالشٌفرونٌة‬ ‫المنشارٌة‬)Chevron Fold
8-‫المروحٌة‬ ‫الطٌة‬Fan Fold
9-‫المتوازٌة‬ ‫الطٌة‬Parallel Fold
10-‫المتشابهة‬ ‫الطٌة‬Similar Fold
-11‫المٌل‬ ‫وحٌدة‬ ‫طٌة‬Monocline Fold
-12‫الطٌات‬‫المطوٌة‬Refolded Folds
13-‫القبة‬Dome‫والحوض‬Basin
25

26. .rocks in the center. twoupward,olderAnticline :fold that is convex
limbs dip away from each other
.: fold that is convex downward. younger rocks in the centerSyncline
two limbs dip toward each other
26

27. Anticline
Syncline
27

28. ‫اي‬ ‫معلوم‬ ‫االعلى‬ ‫الى‬ ‫المحدبة‬ ‫طبقاتها‬ ‫تسلسل‬ ‫ٌكون‬ ً‫الت‬ ‫الطٌات‬ ‫على‬ ‫تطلق‬ ‫المحدبة‬ ‫الطٌة‬
‫تسمى‬ ‫التحدٌد‬ ‫وجه‬ ‫وعلى‬ ‫الطٌة‬ ‫وسط‬ ً‫ف‬ ‫االقدم‬Antiformal Anticline‫عدم‬ ‫وعند‬
‫علٌها‬ ‫ٌطلق‬ ‫االولى‬ ‫الحالة‬ ‫عن‬ ‫ولتمٌٌزها‬ ‫الحقل‬ ً‫ف‬ ‫المحدبة‬ ‫الطٌة‬ ‫طبقات‬ ‫تسلسل‬ ‫معرفة‬
‫اسم‬Antiform.‫االحدث‬ ‫ان‬ ‫اي‬ ‫معكوس‬ ‫المحدبة‬ ‫الطٌة‬ ‫طبقات‬ ‫التسلسل‬ ‫كون‬ ‫حالة‬ ً‫وف‬
‫الطٌة‬ ‫فتسمى‬ ‫االعلى‬ ‫الى‬ ‫واالقدم‬ ‫االسفل‬ ‫الى‬Antiformal Syncline‫لتمٌٌزها‬ ‫وذلك‬
ً‫الطبٌع‬ ‫الطبقات‬ ‫تسلسل‬ ‫ذات‬ ‫المحدبة‬ ‫الطٌة‬ ‫عن‬.
Antiformal Anticline Antiformal Syncline
Antiformal‫و‬ ‫الخارجي‬ ‫للشكل‬Anticline or Syncline‫الطبقي‬ ‫للتابع‬
28

29. ‫الحقل‬ ً‫ف‬ ‫الصحٌح‬ ‫بالوضع‬ ‫المقعرة‬ ‫الطٌة‬ ‫طبقات‬ ‫تسلسل‬ ‫كان‬ ‫اذا‬ ‫اما‬
‫فتسمى‬ ‫االطراف‬ ‫نحو‬ ‫واالقدم‬ ‫الطٌة‬ ‫وسط‬ ً‫ف‬ ‫االحدث‬ ‫الطبقات‬ ‫اي‬
SynclineSynformal,‫فتسمى‬ ‫طبقاتها‬ ‫تسلسل‬ ‫معرفة‬ ‫عدم‬ ‫حالة‬ ً‫وف‬
Synform‫الطبٌعٌة‬ ‫الحالة‬ ‫عن‬ ‫لتمٌٌزها‬ ‫وذلك‬.‫تسلسل‬ ‫كون‬ ‫حالة‬ ً‫وف‬
‫الى‬ ‫واالقدم‬ ‫االسفل‬ ‫الى‬ ‫االحدث‬ ‫اي‬ ً‫ا‬‫معكوس‬ ‫المقعرة‬ ‫الطٌة‬ ‫طبقات‬
‫للطٌة‬ ‫المحوري‬ ‫المستوي‬ ‫باتجاه‬ ‫الداخل‬ ‫الى‬ ‫مائلة‬ ‫واالطراف‬ ‫االعلى‬
‫فتسمى‬ ‫المقعرة‬Synformal Anticline
Synformal Syncline
Synformal Anticline29

30. Overturned Fold ‫المقلوبة‬ ‫او‬ ‫المتكئة‬ ‫الطٌة‬
In overturned fold or overdold the axial plane is inclined,and both limbs dip in the
same direction,usualy at different angles.
The 0verturned,inverted,or reversed limb is one that has been rotated through more than 90⁰
to attain present attitude.
30

31. ‫جٌولوجٌة‬ ‫خارطة‬ ‫على‬ ‫تمثٌلها‬ ‫مع‬ ‫متكئة‬ ‫لطٌة‬ ‫مقطع‬ ً‫التال‬ ‫الشكل‬ ‫وٌمثل‬.‫المستخدمة‬ ‫الرموز‬ ‫الحظ‬
‫المقلوب‬ ‫للطرف‬
31

32. -‫المضطجعة‬ ‫الطٌة‬Recumbent Fold
Axial Plane
A recumbent fold is one in which the axial plane is essentially horizontal or nearly horizontal.
32

33. Isoclinal fold
Folds in which the two limbs dip at equal angles in the same direction.
A vertical isoclinal fold : is one in which the axial plane is vertical.
An inclined or overturned isoclinal fold :is one in which the axial plane is inclined.
A recumbent isoclinal fold :is one in which the axial plane is horizontal.
Many recumbent folds are isoclinal
‫المٌل‬ ‫متساوٌة‬ ‫الطٌة‬
33

34. ‫الصندوقٌة‬ ‫الطٌة‬Box Fold
A box fold is one in which the crest is broad and flat; two hinges are present, one on
either side of the flat crest.
A. P A. P
34

35. -‫المسننة‬ ‫الطٌة‬(‫اوالشٌفرونٌة‬ ‫المنشارٌة‬)Chevron Fold
A chevron fold is one in which the hinges are sharp and angular and the are straight and
(equal length).
35

36. Overturned Chevron Folds in Balambo Formation (Said Sadiq town –Sulamania City)
36

37. ‫ضٌقة‬ ‫مناطق‬ ً‫ف‬ ‫محصورة‬ ‫وصغٌرة‬ ‫متماثلة‬ ‫غٌر‬ ‫تكون‬ ‫الحاد‬ ‫الغلق‬ ‫ذات‬ ‫الطٌات‬ ‫من‬ ‫قسم‬ ‫االحٌان‬ ‫بعض‬ ً‫ف‬
ً‫ف‬ ‫الطبقات‬ ‫مٌل‬ ‫ان‬ ‫حٌث‬ ‫لشرٌط‬ ‫مشابهة‬ ‫امتار‬ ‫لعدة‬ ‫تمتد‬‫الضٌقة‬ ‫المنطقة‬‫امتدادها‬ ‫مٌل‬ ‫من‬ ‫اواكثر‬ ‫اقل‬ ‫اما‬
‫بطٌات‬ ‫الطٌات‬ ‫من‬ ‫النوع‬ ‫هذا‬ ‫على‬ ‫وٌطلق‬ ‫المنطقة‬ ‫هذة‬ ‫خارج‬‫الفتل‬Kink Band‫تقاطع‬ ‫وعند‬‫هذة‬
‫المزدوج‬ ‫بالفتل‬ ‫ٌسمى‬ ‫ما‬ ‫على‬ ‫نحصل‬ ‫بعضها‬ ‫مع‬ ‫الشرائط‬conjugate kink
Kink Band
:A kink Bands
An Asymmetric chevron with a very
long limb and a very short limb metric
Kink bands; are narrow bands, usually only a few inches or few feet wide, in which
the beds assume a dip that is steeper or gentler than that in the adjacent beds.
37

38. ‫الطٌة‬‫المروحٌة‬Fan Fold
‫الطٌة‬‫محور‬‫مستوي‬
A fan fold is both limbs are overturned.
In the anticlinal fan fold, the two limbs dip toward each other;
in the synclinal fan fold, the two limbs dip away from each other.
38

39. A fold is parallel if the thickness of folded layers, measured normal to the bed, is constant
all around the fold. In other words, the strata are bent in parallel curves .
Parallel Fold ‫المتوازٌة‬ ‫الطٌة‬
It is apparent, under such conditions,the form of the fold must change upward and downward.
The Anticline become sharper with depth,but broader and more open upward.
Conversely, the Syncline become broader with depth,but sharper upward.
Parallel folds are typical of competent layers
39

40. In the case of shape of the folds may vary along the axial plane and right angles to
fold axis. Her every bed is thinner in limbs and thicker near the hinges. For this,
there must be consideable plastic movement of material away from the limbs and
towards the hinges.
Similar folds ‫المتشابهة‬ ‫الطٌات‬
Folds of constant bed thickness parallel to axial plane.
40

41. ‫المٌل‬ ‫وحٌدة‬ ‫طٌة‬Monoclinal or Homocline Fold
Monoclines are often the result of
movement along buried faults
Folds with only one limb
41

42. A closed or tight fold; is one in which the deformatio has been sufficiently intense to cause
flowage of the more mobile beds so that these beds thicken and thin.
Conversely,
‫المفتوحة‬ ‫الطٌة‬Open fold
an open fold is one which this flowage has not taken place.
Close or Tight Fold ‫المحكمة‬ ‫او‬ ‫المغلقة‬ ‫الطٌة‬
fold
42

43. ‫المطوٌة‬ ‫الطٌات‬Refolded Folds
‫االرضٌة‬ ‫القشرة‬ ‫طبقات‬ ‫على‬ ‫واجهاد‬ ‫تكتونٌة‬ ‫قوة‬ ‫تأثٌر‬ ‫بسبب‬ ‫تنشأ‬ ‫الطبٌعة‬ ً‫ف‬ ‫الطٌات‬,‫القوة‬ ‫اتجاه‬ ‫ٌتغٌر‬ ‫قد‬ ‫ولكن‬
ً‫ا‬‫سابق‬ ‫المطوٌة‬ ‫للطبقات‬ ً‫ط‬ ‫اواعادة‬ ‫نشوء‬ ‫ٌسبب‬ ‫مما‬,‫اما‬‫محورها‬ ‫مستوي‬ ‫نفس‬ ‫على‬‫ٌتكون‬ ‫او‬‫محوري‬ ‫سطح‬
‫النهائٌة‬ ‫الصورة‬ ‫ٌعقد‬ ‫مما‬ ً‫للط‬ ‫طور‬ ‫اكثر‬ ‫ٌتولد‬ ‫وقد‬ ‫االولى‬ ‫الطٌة‬ ‫محور‬ ‫مستوي‬ ‫على‬ ‫مائال‬ ‫او‬ ‫عمودي‬ ً‫ثان‬
ً‫الجٌولوج‬ ‫للتركٌب‬.‫الى‬ ‫امتدت‬ ‫تكتونٌة‬ ‫بقوة‬ ‫تأثرت‬ ً‫والت‬ ‫معقدة‬ ‫جٌولوجٌة‬ ‫ذات‬ ‫مناطق‬ ً‫ف‬ ‫التعقٌد‬ ‫هذا‬ ‫ونالحظ‬
‫مختلفة‬ ‫واتجاهات‬ ‫ازمان‬ ً‫ف‬ ‫تكتونٌة‬ ‫قوة‬ ‫من‬ ‫اكثر‬ ‫او‬ ‫طوٌلة‬ ‫زمنٌة‬ ‫فترات‬.
Refolded Axial plane
A.P
Imagine a tight to isoclinal recumbent fold being refolded during a later tectonic phase. We
now have a set of secondary synforms and antiforms. The younging direction across their
respective axial surfaces will depend on whether we are on the inverted or upright limb of the
recumbent fold,
In areas affected by two or more deformation phases, a secondary set of folds may
be superimposed on earlier folds.
Refolded folds.Folds modified by a later fold phase are known as
43

44. ‫المحوري‬ ‫المستوي‬ ‫نفس‬ ‫على‬ ً‫الط‬ ‫اعادة‬..‫القدٌمة‬ ‫الطبقات‬ ‫الحظ‬
‫حٌن‬ ً‫ف‬ ً‫الط‬ ‫شدة‬ ‫من‬ ‫زاد‬ ‫مما‬ ‫تكتونٌٌن‬ ‫طورٌن‬ ‫الى‬ ‫تعرضت‬
‫واحد‬ ‫طور‬ ‫الى‬ ‫تعرضت‬ ‫قد‬ ‫االحدث‬ ‫الطبقات‬.
‫اوٌتكون‬‫او‬ ‫عمودي‬ ً‫ثان‬ ‫محوري‬ ‫سطح‬
‫االولى‬ ‫الطٌة‬ ‫محور‬ ‫مستوي‬ ‫على‬ ‫مائال‬
44

45. ً‫ف‬ ‫المعاد‬ ً‫الط‬ ‫استنباط‬ ‫ٌمكن‬‫بع‬‫الخارطة‬ ‫نمط‬ ‫من‬ ‫المواقع‬ ‫ض‬.ً‫ه‬ ً‫للط‬ ‫مراحل‬ ‫ثالثة‬ ‫الشكل‬ ‫ٌرٌنا‬ ‫حٌث‬
F1‫مفتوح‬ ‫متقعر‬ ‫شكل‬ ‫الى‬ ‫طٌها‬ ‫اعٌد‬ ‫قد‬ ‫مضطجعة‬ ‫لطٌة‬ ‫المحوري‬ ‫السطح‬ ‫هو‬F2‫مٌل‬ ‫لهما‬ ‫طرفٌن‬ ‫ذي‬
‫خفٌف‬,‫فتل‬ ‫طٌة‬ ‫تكونت‬ ‫واخٌرا‬(Kink Band Fold) F3
‫المتعددة‬ ‫اطوارها‬ ‫اعمار‬ ‫تحدٌد‬ ‫الصعب‬ ‫من‬ ‫االانه‬ ‫الحقل‬ ً‫ف‬ ً‫الط‬ ‫تتابع‬ ‫استنباط‬ ‫من‬ ‫الرغم‬ ‫على‬_‫متحجرات‬–‫مشعة‬ ‫نظائر‬.
F1 Oldest F2 Intermediate F3 Youngest
ً‫الجٌولوج‬ ‫للتركٌب‬ ‫النهائٌة‬ ‫الصورة‬ ‫ٌعقد‬ ‫مما‬ ً‫للط‬ ‫طور‬ ‫اكثر‬ ‫ٌتولد‬ ‫وقد‬.‫ذات‬ ‫مناطق‬ ً‫ف‬ ‫التعقٌد‬ ‫هذا‬ ‫ونالحظ‬
‫بقوة‬ ‫تأثرت‬ ً‫والت‬ ‫معقدة‬ ‫جٌولوجٌة‬‫تكتونٌة‬‫قوة‬ ‫من‬ ‫اكثر‬ ‫او‬ ‫طوٌلة‬ ‫زمنٌة‬ ‫فترات‬ ‫الى‬ ‫امتدت‬‫تكتونٌة‬‫ازمان‬ ً‫ف‬
‫مختلفة‬ ‫واتجاهات‬
45

46. Refolded Folds
46

47. • Anticlinoria and synclinoria (plural), are large-scale
(10's of km), first-order anticlines and synclines,
respectively, that typically contain second- and third-order
fold sets withen them.
‫العمالقة‬ ‫المحدبة‬ ‫الطٌة‬Anticlinoria‫العمالقة‬ ‫المقعرة‬ ‫الطٌة‬Synclinoria
‫اصغر‬ ‫طٌات‬ ‫عدة‬ ‫من‬ ‫المركبة‬ ‫الرئٌسٌة‬ ‫الطٌات‬ ً‫وه‬.
• Th large, regionally map-able structures.
47

48. Ptygmatic folds: Irregular and isolated single layer folds that
typically occur as tightly folded veins in metamorphic rocks
‫البٌكماتاٌت‬ ‫طٌات‬Ptygmatic folds
‫تتواجد‬ ‫ثابت‬ ‫سمك‬ ‫ذات‬ ‫مفردة‬ ‫طبقة‬ ‫من‬ ‫مؤلفة‬ ‫منتظمة‬ ‫غٌر‬ ‫متعاقبة‬ ‫طٌات‬
‫متحولة‬ ‫صخور‬ ‫ضمن‬ ‫بشدة‬ ‫المطوٌة‬ ‫العروق‬ ً‫ف‬ ً‫مثال‬ ‫بشكل‬.
48

49. Multilayer Folds ‫طبقات‬ ‫عدة‬ ً‫ف‬ ً‫الط‬
‫الختالف‬ ‫وذلك‬ ً‫طباق‬ ‫تتابع‬ ‫ألي‬ ً‫النهائ‬ ً‫الهندس‬ ‫الشكل‬ ً‫وبالتال‬ ً‫الط‬ ‫نمط‬ ً‫ف‬ ‫تتحكم‬ ‫عوامل‬ ‫عدة‬ ‫هنالك‬
‫المسلط‬ ‫الجهد‬ ‫تجاه‬ ‫خواصها‬ ‫باختالف‬ ‫الصخرٌة‬ ‫الطبقات‬ ‫استجابة‬.‫العوامل‬ ‫هذه‬ ‫ومن‬:
-‫التتابع‬ ً‫ف‬ ‫الصلدة‬ ‫الطبقات‬ ‫عدد‬1-Numbers of a Competent Beds.
-‫الصلدة‬ ‫الطبقات‬ ‫سمك‬2-Thickness of a Competent Beds.
-‫الصالدة‬ ‫فرق‬‫صلدة‬ ‫الغٌر‬ ‫الطبقات‬ ‫إلى‬ ‫الصلدة‬ ‫الطبقات‬ ‫بٌن‬3-Competency Contrast Between
Competent and Incompetent Beds.
-‫الصلدة‬ ‫الطبقات‬ ‫بٌن‬ ‫الفاصلة‬ ‫المسافة‬.4-Distance Between Competent Beds.
‫الحرج‬ ‫االنفعال‬ ‫حقل‬Zone of Critical Strainً‫ط‬ ‫فٌه‬ ‫ٌؤثر‬ ‫الذي‬ ‫الحقل‬ ‫هو‬‫صلدة‬ ‫طبقة‬‫سمكا‬ ‫اقل‬ ‫طبقات‬ ‫على‬ ‫سمٌكة‬
‫حولها‬‫وهذا‬‫ٌمتد‬ ‫الحقل‬‫بمقدارنصف‬‫الطول‬ً‫الموج‬(‫الصلدة‬ ‫للطبقة‬)‫بالشكل‬ ‫موضح‬ ‫كما‬ ‫االسفل‬ ‫الى‬ ‫ونصف‬ ‫االعلى‬ ‫الى‬.
‫ظهور‬ ‫إلى‬ ً‫وبالتال‬ ‫صلدة‬ ‫طبقة‬ ‫كل‬ ‫حول‬ ‫الحرج‬ ‫االنفعال‬ ‫حقل‬ ‫تداخل‬ ‫إلى‬ ‫ٌؤدي‬ ‫العوامل‬ ‫تلك‬ ‫بٌن‬ ‫االختالف‬ ‫ان‬
‫التناغم‬ ‫والمتعددة‬ ‫متناغمة‬ ‫والغٌر‬ ‫المتناغمة‬ ‫الطٌات‬.
The main control factors on fold geometry in multilayered folding are:
The wide spectra of fold style and size arises because the mechanical instabilities in a
multilayered sequence depend upon a great number of factors, and nature brings these
factors together in many different folds outline.
contact strainthe adjacent material , an effect termeddisplacesThe growth of a fold
49

50. Dis harmonic folding
‫الحرج‬ ‫االنفعال‬ ‫حقل‬Zone of Critical Strain‫فٌه‬ ‫ٌؤثر‬ ‫الذي‬ ‫الحقل‬ ‫هو‬
‫الحقل‬ ‫وهذا‬ ‫حولها‬ ‫سمكا‬ ‫اقل‬ ‫طبقات‬ ‫على‬ ‫سمٌكة‬ ‫طبقة‬ ً‫ط‬‫بمقدار‬ ‫ٌمتد‬
‫الطول‬ ‫نصف‬‫لطبقة‬ ً‫الموج‬‫موضح‬ ‫كما‬ ‫االسفل‬ ‫الى‬ ‫ونصف‬ ‫االعلى‬ ‫الى‬
‫بالشكل‬.
Z.C.S.
Z.C.S.
½ W
½ W
½ W
50

51. Harmonic folds: correspond with each other in wavelength, symmetry
and general shape
‫المتناغمة‬ ‫الطٌات‬Harmonic Folds
‫الطبقات‬ ‫كانت‬ ‫اذا‬‫متساوٌة‬ ‫الصلدة‬ ‫وغٌر‬ ‫الصلدة‬‫متشابه‬ ‫بٌنهما‬ ‫الصالدة‬ ‫وفرق‬ ‫تقرٌبا‬ ‫ومتساوٌة‬ ‫صغٌرة‬ ‫الفاصلة‬ ‫والمسافة‬ ‫السمك‬,‫لذلك‬
‫وتتداخل‬ ‫تتساوى‬ ‫سوف‬(‫التأثٌر‬ ‫حٌث‬ ‫من‬)‫الصلدة‬ ‫للطبقات‬ ‫الحرجة‬ ‫االنفعال‬ ‫حقول‬,‫الناشئة‬ ‫الطٌات‬ ‫على‬ ‫ٌطلق‬ ‫وعندها‬(‫المتناغمة‬ ‫بالطٌات‬)
Z.C.S.
Z.C.S.
Z.C.S.
Z.C.S.
If the spacing of the layers is smaller so that the zone of contact strain overlaps , then harmonic
folds develop.
51

52. ‫متناغمة‬ ‫الغير‬ ‫الطيات‬Disharmonic Folds
Disharmonic folds: wavelength and shape of folds in adjacent layer are quite different
‫طبقاتها‬ ‫فٌها‬ ‫تكون‬ ً‫الت‬ ‫الطٌات‬ ‫نمط‬ ً‫ه‬‫غٌر‬ ‫الصلدة‬ ‫وغٌر‬ ‫الصلدة‬‫السمك‬ ‫متساوٌة‬‫الفاصلة‬ ‫والمسافة‬
‫كبٌرة‬ ‫بٌنها‬,‫لها‬ ‫ٌنشأ‬ ‫سوف‬ ‫لذلك‬‫حقلٌن‬‫متماثلٌن‬ ‫غٌر‬‫من‬‫الحرج‬ ‫االنفعال‬Zones of critical strain
‫المسافة‬ ‫كبر‬ ‫بسبب‬ ‫بٌنهما‬ ‫تفاعل‬ ‫هناك‬ ‫ولٌس‬.‫السعة‬ ‫حٌث‬ ‫من‬ ‫بخواصها‬ ‫طبقة‬ ‫تحتفظ‬ ‫سوف‬ ‫لذلك‬
‫صلدة‬ ‫الغٌر‬ ‫الطبقات‬ ‫على‬ ‫وتأثٌرها‬ ً‫الموج‬ ‫والطول‬.
Z.C.S.
Z.C.S.
If two or more competent layers are present, but spacing between them is greater than this
zone of contact strain, then the geometry of the folds in each will develop independently. There
will be no necessary relationship between the geometry of these two sets.these are called
disharmonic folds
52

53. ‫متعددة‬ ‫الطٌة‬‫التناغم‬polyharmonic fold
‫الطٌة‬ ‫نمط‬ ‫وهو‬‫طبقاتها‬ ً‫الت‬‫مع‬ ‫الصالدة‬ ‫فرق‬ ‫تغٌر‬ ‫عن‬ ‫فضال‬ ‫متغٌرة‬ ‫بٌنهما‬ ‫والمسافة‬ ‫السمك‬ ‫متساوٌة‬ ‫غٌر‬ ‫الصلدة‬
‫صلدة‬ ‫الغٌر‬ ‫الطبقات‬,‫اكثر‬ ‫ٌنشأ‬ ‫سوف‬ ‫علٌة‬‫حرج‬ ‫انفعال‬ ‫حقل‬ ‫من‬Zones of Critical strain(‫متماثل‬ ‫غٌر‬)
‫متناغم‬ ‫غٌر‬ ً‫ط‬ ‫نمط‬ ً‫ٌعط‬ ‫مما‬
Polyharmonic folding
Z.C.S.
Z.C.S.
Z.C.S.
Z.C.S.
If thin competent layers lie within the zone of contact strain of thicker layers , there
will be a partial connection between the folds sets.
53

54. Fold Harmony
54

55. 55

56. ‫القبة‬Dome
‫ل‬ ‫لٌس‬ ‫محدب‬ ‫رفع‬ ً‫ه‬‫ه‬‫ممٌز‬ ‫اتجاه‬.
Dome
A dome is an anticlinal uplift that has
no distinct trend
‫واالحدث‬ ‫االقدم‬ ‫التكوينات‬ ‫انكشاف‬ ‫الحظ‬
56

57. ‫الحوض‬Basin
‫اتجاه‬ ‫له‬ ‫لٌس‬ ‫مقعر‬ ‫خفض‬‫ممٌز‬
‫الحظ‬‫واالحدث‬ ‫االقدم‬ ‫التكوينات‬ ‫انكشاف‬
A basin is a synclinal depression
that has no distinct trend.
57

58. Aerial photo of a structural dome. Rocks dip away from the
center.
58