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Igneous Rocks -- II Intermediate Rocks Acidic Rocks.

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Presentation on theme: "Igneous Rocks -- II Intermediate Rocks Acidic Rocks."— Presentation transcript:

1 Igneous Rocks -- II Intermediate Rocks Acidic Rocks

2 Classifications: minerals & chemical compositions

3 Intermediate Rocks TextureAlkali feldspar < 1/3 Alkali feldspar >1/3 < 2/3 Alkali feldspar >2/3 Feldspathoidal Volcanic rocks AndesiteTrachyandesite (latite) TrachytePhonolite Plutonic rocks DioriteMonzoniteSyeniteFeldspathoidal syenite

4 Diorite Definition: is intrusive, holocryatalline, phaneritic, containing: Plagioclase (oligoclase or andesine)----- 55~70% Mafic (commomly hornblende or biotite)---- - 40~25%

5 Diorite: Plag+ Mafic ( Hb, Cpx, Bi)

6 Trachytoid Diorite

7 Andesite Definition: is volcanic and hypabyssal intrusive, holocryatalline or hypocrystalline, with matrix aphanetic, containing: Plagioclase (oligoclase or andesine)----- 55~70% Mafic (commomly hornblende or biotite)---- - 40~25%

8 Andesite: Plag+Mafic (Cpx, Hb, Bi)

9 Porphyritic Andesite

10 High-Mg andesite: Plag+Opx+Ol

11 Tonolite (quartz andesite) Definition: is intrusive, plutonic and hypabyssal, holocryatalline, phaneritic, containing: Sodic plagioclase (oligoclase or andesine)-- ---50~80% Quartz ---- 35~10% Mafic (biotite and hornblende)----- 35~10%

12 Tonalite: Plag+Mafic (Bi, Hb) +quartz (< 10%)

13 Dacite (quartz andesite) Definition: is volcanic and hypabyssal intrusive, holocryatalline or hypocrystalline, with matrix aphanetic, containing: Sodic plagioclase (oligoclase or andesine)-- ---50~80% Quartz ---- 35~10% Mafic (biotite and hornblende)----- 35~10%

14 Dacite: Plag+Mafic (Bi, Hb) +quartz (< 10%)

15 Monzonite Definition: is intrusive, Plutonic or hypabyssal, holocryatalline, phaneritic, containing: Mafic (hornblende, biotite, augite)----- 15~60% Sodic Plagioclase (oligoclase or andesine)-- ---50~30% Potash feldspar (orthoclase) ----- 45~25%

16 Monzonite: Plag+K-feldspar +Mafic (Bi, Hb, Aug)

17 Latite Definition: is volcanic and hypabyssal intrusive, holocryatalline or hypocrystalline, with matrix aphanetic, containing: Mafic (hornblende, biotite, augite)----- 15~60% Sodic Plagioclase (oligoclase or andesine)-- ---50~30% Potash feldspar (orthoclase) ----- 45~25%

18 Syenite Definition: is intrusive, Plutonic or hypabyssal, holocryatalline, phaneritic, containing: Alkali feldspar (orthoclase) ----- 30~80% Sodic Plagioclase (oligoclase or andesine)-- ---5~25% Mafic (hornblende, biotite, augite)----- 40~10%

19 Syenite: K-feldspar+ Plag +Mafic (Bi, Hb, Px)

20 Trachyte Definition: is volcanic and hypabyssal intrusive, holocryatalline or hypocrystalline, with matrix aphanetic, containing: Alkali feldspar (orthoclase) ----- 45~80% Sodic Plagioclase (oligoclase or andesine)-- ---5~25% Mafic (hornblende, biotite, augite)----- 30~10%

21 Trachyte: K-feldspar+ Plag +Mafic (Bi, Hb, Px)

22 Acidic rocks or Silicic Rocks Granite Rhyolite Granodiorite Quartz latite

23 Granite Definition: is plutonic, intrusive, and hypabyssal, holocryatalline, phaneritic, containing: Quartz ----- 10~40% Potash feldspar ----- 30~60% Sodic plagioclase (excluding perthite)----- 0~35% Mafic (biotite, hornblende)----- 40~25%

24 Calc-alkali granite Perthitic orthoclase or microcline Oligoclase or rarely andesine Hornblende Diopside or augite Alkali granite Strongly perthite orthoclase or microcline, anorthoclase Albite or sodic oligoclase Iron-rich biotite Hastingsite, arfvedsonite, riebeckite Aegirine-augite, rarely hedbergite

25 Granite

26

27 Granite: Or + Qz + Mica (Bi, Mus)

28

29 Microcline

30 Perthite

31 Alkali granite: Or + Qz + Alkali Hb

32 Rhyolite Definition: is volcanic and hypabyssal, holocryatalline or hypocrystalline, with matrix aphanetic, containing: Quartz ----- 10~40% Potash feldspar ----- 30~60% Sodic plagioclase (excluding perthite)----- 0~35% Mafic (biotite, hornblende)----- 40~25%

33 Rhyolite

34

35 Obsidian

36 Rhyolite: Or + Qz

37

38 Rhyolite: Or + Qz

39 Pumice

40 Granodiorite Definition: is plutonic and intrusive, holocryatalline, phaneritic, containing: Potash feldspar ----- 20~40% Sodic plagioclase-----25~45% Quartz ----- 35~10% Mafic (biotite, hornblende)----- 30~10%

41 Granodiorite: Or + Plag + Qz + Mafic (Bi, Hb)

42 Granodiorite: Or + Plag + Qz + Mafic (Bi, Hb)

43 Quartz latite Definition: is volcanic and hypabyssal, holocryatalline or vitrous, with matrix aphanetic, containing: Potash feldspar ----- 20~30% Sodic plagioclase-----30~50% Quartz ----- 35~10% Mafic (biotite, hornblende)----- 20~10%

44 Ultrabasic and basic rocks

45 Classifications: minerals & chemical compositions

46 Definition Peridotite is holocrystalline, phaneritic, plutonic rocks; containing Mafic (Ol, Px, Hb) --------- 85-95% Ores (magnetite, ilmenite, chromite)---10- 3% Calcic plagioclase ------< 5%

47

48 Classification Peridotite ---- group name Ol ------- Dunite Ol + OPX (En or Hy) ----Harzburgite Ol + CPX (aug) -------- Wehrite Ol + OPX + CPX ---- Lherzolite Ol + Hb -------- Cortlandtite Px (CPX + OPX) ----- Pyroxenite Hb ---------- Hornblendite Kimberlite --- mica peridotite

49 Dunite — olivine + chromium-rich spinel

50 Harbuzite — Olivine + OPX

51 Wehrite — Olivine + CPX

52 Lherzolite — Olivine + OPX + CPX

53 Garnet peridotite

54 Pyroxenite--- CPX + OPX

55 Hornblendite- -- Hb

56 Kimberlite --- mica peridotite

57 Fine-grained ultramafic rocks Komatiite ankaramite --- Diopside augite Limburgite --- Augite Katungite --- melilite-rich Ol leucitite Ugandite --- melanocratic Ol leucitite Melilitite & nephelinitite --- nepheline basalt Basanite

58 Komatiite

59 Leucitite

60

61 Meymechite

62 Basanite

63 Ultramafic vs. Ultrabasic Mafic mineral: > 70% Ultramafic  ultrabasic SiO2 < 45 wt% Ultrabasic ~ ultramafic Ex. Carbonatite, anorthosite

64 Carbonatite

65 Basic rocks Volcanic rocks: Tholeiite: Cpx+Plag Alkali basalts: Plag+Cpx+Ol Picrite: Ol  Plag Plutonic Rocks Diabase Gabbro: Plag + Cpx Norite: Plag + Opx Eucrite: Calcic Plag + Opx Troctolite: Ol +Plag Anorthosite: Plag  Mafic

66 Gabbro Definition: is intrusive, plutonic, holocrystalline, phaneritic rocks. Containing: Mafic (aug, Hy, or Ol less commomly Hb) ---25- 50% Plagioclase (labradonite or bytownite) ---- 70- 45%

67 Classifications Gabbro --- Aug + Calcic Plag Ol-gabbro --- Aug + Ol + Calcic Plag Troctolite --- Ol + Calcic Plag Norite --- Hy + Calcic Plag Anorthosite --- Ol + Calcic Plag

68 Diabase (dolerite) Definition: is intrusive, hypabyssal, normally holocrystalline Containing Mafic (aug, Hy, less commomly Ol) ---65- 25% Plagioclase (labradonite or bytownite) ---- 30-70%

69 Basalts Definition: is volcanic and uncommonly hypabyssal intrusive, holocrystalline, hypocrystalline rarely vitrous matrix aphanitic. Containing Plagioclase (labradonite) ---- 40-60% Mafic (aug, Ol) ---55-35%

70 Tholeiitic basalt: Cpx  Plag ± Ol

71 Alkali basalt: Plag + Ol  Cpx

72 Lunar low-Ti basalt: Plag + Ol  Cpx

73 Lunar high-Ti basalt: Plag  Cpx ± Ol

74 Picrite basalt: Ol  Cpx±Plag

75 Glassy groundmass

76 Vesiculated basalt

77 Gabbro: Plag+Cpx

78 Alkali gabbro: Plag+Cpx±Ol

79 Alkali Gabbro: Plag+Ol+Cpx±K- feldspar or ±Feldspathoid

80 Basic dike rocks Diabase

81 Norite: Plag+Opx

82 Anorthosite: Plag ± Mafic (< 10%)


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