159:
742:
323:
medium. High energy currents can carry larger fragments. As the energy decreases, heavier particles are deposited and lighter fragments continue to be transported. This results in sorting due to density. Sorting can be expressed mathematically by the standard deviation of the grain-size frequency curve of a sediment sample, expressed as values of φ (phi). Values range from <0.35φ (very well sorted) to >4.00φ (extremely poorly sorted).
402:
136:
656:
Porphyritic structure is caused by the nucleation of crystal sites and the growth of crystals in a liquid magma. Often a magma can only grow one mineral at a time especially if it is cooling slowly. This is why most igneous rocks have only one type of phenocryst mineral. Rhythmic cumulate layers in
420:
Linear structures in a rock may arise from the intersection of two foliations or planar structures, such as a sedimentary bedding plane and a tectonically induced cleavage plane. The degree of lineation compared with the degree of foliation for certain strain markers in deformed rocks are commonly
704:
lavas. Here, low nucleation rates due to superfluidity prevent nucleation until the liquid is well below the mineral growth curve. Growth then occurs at extreme rates, favoring slender, long crystals. Additionally, at crystal vertices and terminations, spikes and skeletal shapes may form because
441:
planes form oblique to the shear plane. The angle between the C and S planes is always acute, and defines the shear sense. Generally, the lower the C-S angle the greater the strain. The C' planes are rarely observed except in ultradeformed mylonites, and form nearly perpendicular to the S-plane.
322:
Sorting is used to describe the uniformity of grain sizes within a sedimentary rock. Understanding sorting is critical to making inferences on the degree of maturity and length of transport of a sediment. Sediments become sorted on the basis of density, because of the energy of the transporting
393:
Identifying a foliation and its orientation is the first step in analysis of foliated metamorphic rocks. Gaining information on when the foliation formed is essential to reconstructing a P-T-t (pressure, temperature, time) path for a rock, as the relationship of a foliation to
737:
Intergrowths of two or more minerals can form in a variety of ways, and interpretations of the intergrowths can be critical in understanding both magmatic and cooling histories of igneous rocks. A few of the many important textures are presented here as examples.
58:. Textures can be quantified in many ways. A common parameter is the crystal size distribution. This creates the physical appearance or character of a rock, such as grain size, shape, arrangement, and other properties, at both the visible and microscopic scale.
261:
Roundness refers to the degree of sharpness of the corners and edges of a grain. The surface texture of grains may be polished, frosted, or marked by small pits and scratches. This information can usually be seen best under a binocular microscope, not in a
216:
Methods involve description of clast size, sorting, composition, rounding or angularity, sphericity and description of the matrix. Sedimentary microstructures, specifically, may include microscopic analogs of larger sedimentary structural features such as
724:
is the result of cooling and nucleation of material in a magma which has achieved supersaturation in the crystal component. Thus it is often a subsolidus process in supercooler felsic rocks. Often, two minerals will grow together in the spherulite.
48:(in which crystals are not visible to the unaided eye), and glassy (in which the particles are too small to be seen and amorphously arranged). The geometric aspects and relations amongst the component particles or crystals are referred to as the
253:. The more rounded the clasts, the more water or wind-worn they are. Particle shape includes form and rounding. Form indicates whether a grain is more equant (round, spherical) or platy (flat, disc-like, oblate); as well as sphericity.
494:
microstructures can provide information on source and genesis, including contamination of igneous rocks by wall rocks and identifying crystals which may have been accumulated or dropped out of the melt. This is especially critical for
102:. Phaneritic textures are where interlocking crystals of igneous rock are visible to the unaided eye. Foliated texture is where metamorphic rock is made of layers of materials. Porphyritic texture is one in which larger pieces (
43:
is composed. The broadest textural classes are crystalline (in which the components are intergrown and interlocking crystals), fragmental (in which there is an accumulation of fragments by some physical process),
274:
Composition of the clasts can give clues as to the derivation of a rock's sediments. For instance, volcanic fragments, fragments of cherts, well-rounded sands all imply different sources.
802:
is a microscopic, vermicular (worm-like) intergrowth of quartz and sodium-rich plagioclase common in granite; myrmekite may form as alkali feldspar breaks down by exsolution and
771:, and they have been interpreted as documenting simultaneous crystallization of the intergrown minerals in the presence of a silicate melt together with a water-rich phase.
809:
Iron-titanium oxides are extremely important, as they carry the predominant magnetic signatures of many rocks, and so they have played a major role in our understanding of
664:
When a rock cools too quickly the liquid freezes into a solid glass, or crystalline groundmass. Often vapor loss from a magma chamber will cause a porphyritic texture.
429:
Very distinctive textures form as a consequence of ductile shear. The microstructures of ductile shear zones are S-planes, C-planes and C' planes. S-planes or
693:) which best reflects its environment and cooling rate. The usual phenocryst habit is the ones commonly observed. This may imply a 'normal' cooling rate.
518:), magma composition and its relationships to what minerals will nucleate, as well as physical effects of wall rocks, contamination and especially vapor.
335:
microstructures aims to determine the timing, sequence and conditions of deformations, mineral growth and overprinting of subsequent deformation events.
713:
texture is an example of this result. Hence, the shape of phenocrysts can provide valuable information on cooling rate and initial magma temperature.
965:
Texture & Genesis of Rocks, Introductory
Geology Laboratory, Christopher DiLeonardo, Ph.D., Marek Cichanski, Ph.D., Earth & Space Sciences,
759:, and granophyric textures are examples of intergrowths formed during magmatic crystallization. They are angular intergrowths of quartz and
1008:
670:
or 'corroded' margins to phenocrysts infer that they were being resorbed by the magma and may imply addition of fresh, hotter magma.
763:. When well-developed, the intergrowths may resemble ancient cuneiform writing, hence the name. These intergrowths are typical of
83:
Microstructure analysis describes the textural features of the rock, and can provide information on the conditions of formation,
471:
microstructure may complement descriptions on the hand-sized specimen and outcrop scale. This is especially vital for describing
76:, except a texture does not necessarily carry structural information in terms of deformation events and orientation information.
599:
Crystal shape is also an important factor in the texture of an igneous rock. Crystals may be euhedral, subeuhedral or anhedral:
1116:
794:
of intermediate composition: the coarseness of perthitic intergrowths is related to cooling rate. Perthite is typical of many
350:
to the foliations and to other porphyroblasts can provide information on the order of formation of metamorphic assemblages or
193:
is still acceptable because it is a useful means of identifying the origin of rocks, how they formed, and their appearance.
484:
17:
378:
On the thin section and hand-sized specimen scale a metamorphic rock may manifest a planar penetrative fabric called a
233:
and deviations), but also to the fragment sphericity, rounding and composition. Quartz-only sands are more mature than
1158:
991:
939:
132:
in which its grains have a flattened shape (inequant), and their planes tend to be oriented in the same direction.
125:
68:
of rocks; they occur throughout the entirety of the rock mass on microscopic, hand-sized specimen, and often
729:
texture results from spherulitic growth along fractures in volcanic glass, often from invasion of water.
282:
The matrix of a sedimentary rock and the mineral cement (if any) holding it together are all diagnostic.
983:
931:
875: – Branch of geology that studies the formation, composition, distribution and structure of rocks
813:. These oxides commonly have complex textures related both to exsolution and oxidation. For instance,
1059:"Formation of synthetic structures and textures of rocks when simulating in COMSOL Multiphysics"
405:
Flinn
Diagram showing degree of stretching, or lineation (L) versus flattening, or foliation (S)
545:: rapid cooling, crystal nucleation and growth is stunted, forming a uniform, fine grained rock
398:
is diagnostic of when the foliation formed, and the P-T conditions which existed at that time.
360:
textures are particularly suited to analysis by microstructural investigations, especially in
884:
842:
50:
1023:
756:
628:
584:: rock formed of fragments of crystals, phenocrysts and rock fragments of a volcanic origin
774:
Intergrowths that form by exsolution are aids in interpreting cooling histories of rocks.
8:
863: – Science of the description and interpretation of deformation in the Earth's crust
721:
633:
514:
Igneous microstructure is a combination of cooling rate, nucleation rate, eruption (if a
415:
379:
373:
339:
295:
189:
are interchangeable, with the latter preferred in modern geological literature. However,
95:
73:
1027:
1173:
1088:
1039:
860:
848:
383:
250:
77:
1154:
1092:
1080:
1043:
987:
935:
899:
561:
539:: rocks contain minerals with crystals visible to the unaided eye, commonly intrusive
437:
or platy minerals. Define the flattened long-axis of the strain ellipse. C-planes or
299:
163:
158:
1124:
1075:
1035:
1070:
1031:
893:
741:
671:
581:
556:
332:
311:
210:
202:
129:
118:
64:
857: – Change of minerals in pre-existing rocks without melting into liquid magma
205:
microstructure aims to provide information on the conditions of deposition of the
966:
887: – distribution of crystallographic orientations of a polycrystalline sample
810:
752:
745:
690:
357:
825:
commonly oxidizes during subsolidus cooling to produce regular intergrowths of
491:
178:
40:
710:
1167:
1084:
1058:
866:
456:
395:
347:
230:
218:
706:
526:
According to the texture of the grains, igneous rocks may be classified as
905:
854:
833:. The process can determine what magnetic record is inherited by the rock.
587:
468:
263:
140:
84:
433:
planes are parallel with the shear direction and are generally defined by
338:
Metamorphic microstructures include textures formed by the development of
697:
548:
387:
343:
103:
99:
221:, syn-sedimentary faults, sediment slumping, cross-stratification, etc.
980:
Quantitative
Textural Measurements in Igneous and Metamorphic Petrology
902: – Texture of small enclosed cavities found in some volcanic rocks
814:
787:
768:
675:
658:
552:
536:
503:
472:
307:
291:
114:
91:
674:
is also used to explain some porphyritic igneous textures, especially
878:
872:
826:
799:
764:
726:
701:
678:
620:
542:
530:
496:
238:
147:
45:
1009:"Tortuosity of porous media: Image analysis and physical simulation"
229:
The maturity of a sediment is related not only to the sorting (mean
1063:
Gornye Nauki I Tekhnologii = Mining
Science and Technology (Russia)
830:
791:
779:
775:
760:
604:
361:
206:
144:
803:
795:
636:, if the crystals present no recognizable crystallographic forms.
575:
303:
110:
69:
28:
869: – Study of natural sediments and their formation processes
386:. Several foliations may be present in a rock, giving rise to a
822:
818:
783:
644:, and rocks composed entirely of subhedral crystals are termed
509:
351:
234:
106:) are embedded in a background mass made of much finer grains.
483:
and phenocryst morphology are critical for analysing cooling,
571:
567:
480:
401:
302:
and sub-grain deformation. Mineralogical changes may include
87:, and subsequent deformation, folding, or alteration events.
1007:
Fu, Jinlong; Thomas, Hywel R.; Li, Chenfeng (January 2021).
445:
Other microstructures which can give sense of shear include
135:
39:
refers to the relationship between the materials of which a
515:
499:
476:
434:
151:
732:
1056:
640:
Rocks composed entirely of euhedral crystals are termed
1057:
Voznesensky, A. S.; Kidima-Mbombi, L. K. (2021-07-14).
661:
intrusions are a result of uninterrupted slow cooling.
1121:
Tulane
University - Earth & Environmental Sciences
845: – List of rock textural and morphological terms
177:
includes the texture and small-scale structures of a
889:
Pages displaying wikidata descriptions as a fallback
564:: contains voids caused by trapped gas while cooling
851: – List of rock types recognized by geologists
298:. Other effects can include flattening of grains,
249:Fragment shape gives information on the length of
213:, and the provenance of the sedimentary material.
689:A crystal growing in a magma adopts a habit (see
684:
1165:
424:
80:occur on a hand-sized specimen scale and above.
364:and other highly disturbed and deformed rocks.
1105:Essentials of Geology, 3rd Ed, Stephen Marshak
881: – Structures in rock caused by extension
367:
196:
612:, if the crystallographic shape is preserved.
326:
510:General principles of igneous microstructure
806:is transported by fluids in cooling rocks.
1006:
1074:
462:
1151:A Practical Guide to Rock Microstructure
928:A practical guide to rock microstructure
740:
651:
400:
157:
134:
72:scales. This is similar in many ways to
977:
342:and overprinting of foliations causing
14:
1166:
925:
733:Graphic and other intergrowth textures
285:
961:
959:
957:
955:
953:
951:
705:growth is favoured at crystal edges.
590:: rock crystals are all the same size
277:
1153:, Oxford University Press, Oxford.
24:
1143:
1114:
948:
25:
1185:
1099:
896: – Property of igneous rocks
594:
479:, as often relationships between
244:
696:Abnormal cooling rates occur in
521:
294:results in a weak bedding-plane
1076:10.17073/2500-0632-2021-2-65-72
1036:10.1016/j.earscirev.2020.103439
169:
1108:
1050:
1000:
971:
919:
716:
685:Phenocryst shape: implications
310:minerals forming in low-grade
269:
13:
1:
912:
425:Ductile shear microstructures
409:
162:Texture in a thin section of
126:preferred mineral orientation
90:Crystalline textures include
624:, if only part is preserved.
421:plotted on a Flinn diagram.
256:
109:Fragmental textures include
7:
836:
475:and fragmental textures of
368:Foliations and crenulations
224:
197:Sedimentary microstructures
10:
1190:
984:Cambridge University Press
932:Cambridge University Press
908: – Property of a soil
485:fractional crystallization
413:
371:
327:Metamorphic microstructure
317:
817:in igneous rocks such as
51:crystallographic texture
978:Higgins, M. D. (2006).
1149:Vernon, Ron H., 2004,
926:Vernon, R. H. (2004).
749:
463:Igneous microstructure
406:
346:. The relationship of
166:
155:
1016:Earth-Science Reviews
885:Texture (crystalline)
843:List of rock textures
778:is an intergrowth of
744:
700:magmas, particularly
652:Porphyritic structure
533:: very large crystals
404:
161:
138:
56:preferred orientation
786:feldspar, formed by
300:pressure dissolution
128:, is the texture of
1117:"Sedimentary Rocks"
1115:Nelson, Stephen A.
1028:2021ESRv..21203439F
722:Spherulitic texture
416:Lineation (geology)
374:Foliation (geology)
286:Diagenetic features
175:Rock microstructure
37:rock microstructure
18:Rock microstructure
861:Structural geology
849:List of rock types
750:
407:
251:sediment transport
167:
156:
900:Vesicular texture
506:intrusive rocks.
487:and emplacement.
278:Matrix and cement
164:tholeiitic basalt
16:(Redirected from
1181:
1137:
1136:
1134:
1132:
1123:. Archived from
1112:
1106:
1103:
1097:
1096:
1078:
1054:
1048:
1047:
1013:
1004:
998:
997:
975:
969:
963:
946:
945:
923:
894:Igneous textures
890:
672:Ostwald ripening
578:without crystals
333:metamorphic rock
211:paleoenvironment
203:sedimentary rock
130:metamorphic rock
21:
1189:
1188:
1184:
1183:
1182:
1180:
1179:
1178:
1164:
1163:
1146:
1144:Further reading
1141:
1140:
1130:
1128:
1113:
1109:
1104:
1100:
1055:
1051:
1011:
1005:
1001:
994:
976:
972:
967:De Anza College
964:
949:
942:
924:
920:
915:
888:
839:
811:plate tectonics
792:alkali feldspar
761:alkali feldspar
746:Graphic granite
735:
719:
691:crystallography
687:
654:
597:
524:
512:
465:
449:sigmoidal veins
427:
418:
412:
376:
370:
329:
320:
288:
280:
272:
259:
247:
227:
201:Description of
199:
172:
23:
22:
15:
12:
11:
5:
1187:
1177:
1176:
1162:
1161:
1145:
1142:
1139:
1138:
1127:on 3 July 2012
1107:
1098:
1049:
999:
992:
970:
947:
940:
917:
916:
914:
911:
910:
909:
903:
897:
891:
882:
876:
870:
864:
858:
852:
846:
838:
835:
734:
731:
718:
715:
686:
683:
653:
650:
646:subidiomorphic
642:panidiomorphic
638:
637:
625:
613:
596:
595:Crystal shapes
593:
592:
591:
585:
579:
565:
559:
546:
540:
534:
523:
520:
511:
508:
492:intrusive rock
464:
461:
460:
459:
457:porphyroblasts
453:
450:
426:
423:
414:Main article:
411:
408:
396:porphyroblasts
372:Main article:
369:
366:
348:porphyroblasts
328:
325:
319:
316:
287:
284:
279:
276:
271:
268:
258:
255:
246:
245:Fragment shape
243:
226:
223:
198:
195:
187:microstructure
171:
168:
9:
6:
4:
3:
2:
1186:
1175:
1172:
1171:
1169:
1160:
1159:0-521-89133-7
1156:
1152:
1148:
1147:
1126:
1122:
1118:
1111:
1102:
1094:
1090:
1086:
1082:
1077:
1072:
1068:
1064:
1060:
1053:
1045:
1041:
1037:
1033:
1029:
1025:
1021:
1017:
1010:
1003:
995:
993:0-521-13515-X
989:
985:
982:. Cambridge:
981:
974:
968:
962:
960:
958:
956:
954:
952:
943:
941:0-521-81443-X
937:
933:
929:
922:
918:
907:
904:
901:
898:
895:
892:
886:
883:
880:
877:
874:
871:
868:
867:Sedimentology
865:
862:
859:
856:
853:
850:
847:
844:
841:
840:
834:
832:
828:
824:
820:
816:
812:
807:
805:
801:
797:
793:
789:
785:
781:
777:
772:
770:
766:
762:
758:
754:
747:
743:
739:
730:
728:
723:
714:
712:
708:
703:
699:
694:
692:
682:
680:
677:
673:
669:
665:
662:
660:
649:
647:
643:
635:
631:
630:
626:
623:
622:
617:
614:
611:
607:
606:
602:
601:
600:
589:
586:
583:
580:
577:
573:
569:
566:
563:
560:
558:
554:
551:: containing
550:
547:
544:
541:
538:
535:
532:
529:
528:
527:
522:Grain texture
519:
517:
507:
505:
501:
498:
493:
488:
486:
482:
478:
474:
470:
458:
454:
451:
448:
447:
446:
443:
440:
436:
432:
422:
417:
403:
399:
397:
391:
389:
385:
381:
375:
365:
363:
359:
355:
354:of minerals.
353:
349:
345:
341:
336:
334:
331:The study of
324:
315:
313:
309:
305:
301:
297:
293:
283:
275:
267:
265:
254:
252:
242:
240:
236:
232:
222:
220:
219:cross-bedding
214:
212:
208:
204:
194:
192:
188:
184:
180:
176:
165:
160:
153:
149:
146:
142:
139:Texture in a
137:
133:
131:
127:
122:
120:
116:
112:
107:
105:
101:
97:
93:
88:
86:
81:
79:
75:
71:
67:
66:
61:Textures are
59:
57:
53:
52:
47:
42:
38:
34:
30:
19:
1150:
1129:. Retrieved
1125:the original
1120:
1110:
1101:
1069:(2): 65–72.
1066:
1062:
1052:
1019:
1015:
1002:
979:
973:
927:
921:
906:Soil texture
855:Metamorphism
808:
773:
757:micrographic
751:
736:
720:
695:
688:
667:
666:
663:
655:
645:
641:
639:
627:
619:
615:
609:
603:
598:
588:equigranular
525:
513:
490:Analysis of
489:
469:igneous rock
467:Analysis of
466:
444:
438:
430:
428:
419:
392:
377:
356:
344:crenulations
337:
330:
321:
314:conditions.
289:
281:
273:
264:thin section
260:
248:
228:
215:
200:
190:
186:
182:
181:. The words
174:
173:
170:Nomenclature
141:thin section
123:
108:
89:
85:petrogenesis
82:
63:penetrative
62:
60:
55:
49:
36:
32:
26:
748:from Norway
717:Spherulites
698:supercooled
679:megacrystic
634:xenomorphic
616:Subeuhedral
610:automorphic
582:pyroclastic
553:phenocrysts
549:porphyritic
473:phenocrysts
439:cissalement
431:schistosity
388:crenulation
312:metamorphic
270:Composition
119:pyroclastic
104:phenocrysts
100:porphyritic
1022:: 103439.
913:References
815:ulvospinel
788:exsolution
780:K-feldspar
769:granophyre
681:granites.
676:orthoclase
668:Embayments
659:ultramafic
557:groundmass
555:in a fine
537:phaneritic
531:pegmatitic
504:ultramafic
410:Lineations
308:authigenic
292:diagenesis
231:grain size
115:bioclastic
92:phaneritic
78:Structures
74:foliations
1174:Petrology
1093:237797248
1085:2500-0632
1044:229386129
879:Boudinage
873:Petrology
827:magnetite
800:Myrmekite
765:pegmatite
727:Axiolitic
711:dendritic
702:komatiite
621:Subhedral
562:vesicular
543:aphanitic
497:komatiite
452:mica fish
380:foliation
362:mylonites
340:foliation
306:or other
296:foliation
257:Roundness
239:greywacke
150:from the
148:quartzite
145:mylonitic
46:aphanitic
1168:Category
837:See also
831:ilmenite
796:granites
790:from an
776:Perthite
707:Spinifex
629:Anhedral
605:Euhedral
568:vitreous
455:rotated
384:cleavage
290:Usually
225:Maturity
207:sediment
96:foliated
1131:8 April
1024:Bibcode
804:silicon
753:Graphic
576:hyaline
318:Sorting
304:zeolite
191:texture
183:texture
154:, Italy
111:clastic
70:outcrop
65:fabrics
33:texture
29:geology
1157:
1091:
1083:
1042:
990:
938:
823:gabbro
819:basalt
784:albite
572:glassy
352:facies
235:arkose
209:, the
117:, and
98:, and
1089:S2CID
1040:S2CID
1012:(PDF)
782:with
500:lavas
481:magma
477:tuffs
435:micas
382:or a
358:Shear
1155:ISBN
1133:2021
1081:ISSN
988:ISBN
936:ISBN
829:and
821:and
767:and
516:lava
502:and
185:and
179:rock
152:Alps
41:rock
1071:doi
1032:doi
1020:212
709:or
632:or
618:or
608:or
574:or
237:or
143:of
54:or
35:or
27:In
1170::
1119:.
1087:.
1079:.
1065:.
1061:.
1038:.
1030:.
1018:.
1014:.
986:.
950:^
934:.
930:.
798:.
755:,
648:.
570::
390:.
266:.
241:.
124:A
121:.
113:,
94:,
31:,
1135:.
1095:.
1073::
1067:6
1046:.
1034::
1026::
996:.
944:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
