암석성인격자 (Petrogenetic grids) Determination of Metamorphic P-T condition 평형상태에있는광물의조합 평형상태일때, 광물학 ( 각광물의성분은 T, PandX P, 에의해결정됨. 광물성인 은평형광물조합과관련됨. 잔류광물또는후기의변질산물은특별한경우를제외하고배제된다. Al 2 SiO 5 Figure 21-9. The P-T phase diagram for the system Al 2 SiO 5 calculated using the program TWQ (Berman, 1988, 1990, 1991). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. Figure 23-53. Reaction rims and coronas. From Passchier and Trouw (1996) Microtectonics. Springer-Verlag. 암석성인격자 (Petrogenetic grids) 다중성분시스템을위한 P-T diagrams 으로, 일반적으로특정암석에서광물반응들의조합을보여줌 암석의성분에따라서다양한반응곡선존재 Petrogenetic grid for mafic rocks Petrogenetic grid for pelitic rock Fig. 26-19. Simplified petrogenetic grid for metamorphosed mafic rocks showing the location of several determined univariant reactions in the CaO-MgO-Al 2 O 3 -SiO 2 -H 2 O-(Na 2 O) system ( C(N)MASH ). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. 1
가상 (Pseudosection) 암석성인격자와유사한다이어그램 암석성인격자 : 광물들의특정 P-T에서반응곡선을나열 가상 : 특정광물조합이안정한 P-T 범위를보여줌. 장점 : 박편등에서관찰한안정광물의조합을직접적으로비교할수있다 ( 직관적 ) 단점 : 암석의종류에따라서다양한다이어그램이산출되기때문에적용에주의 가상 (Pseudosection) Phase equilibrium diagrams constructed by the Theriak-Domino using TWQ database (a) and the program Gibbs (b; Spear, 1989, AM, 74, 942-943) using dataset of Holland & Powell (1998, JMG, 16, 309-343). Cheong s unpublish data a 가상 (Pseudosection) b c 암석성인격자와가상의비교 d e f g Comparison with petrogenetic (left) grid and pseudosection (right) of pelites composition constructed with KFMASH system ( 지온지압계 ) ( 지온지압계 ) Fe 3 Al 2 Si 3 O 12 + KMg 3 AlSi 3 O 10 (OH) 2 Fe 석류석 + Mg 흑운모 자연시료에서압력과온도를판단하기위해 알려진온도압력조건에서공존하는상들의 원소들의분포를측정하여이용함. Mg 3 Al 2 Si 3 O 12 + KFe 3 AlSi 3 O 10 (OH) 2 Mg 석류석 + Fe 흑운모 K D ( Fe / Mg) = ( Fe / Mg) biotite garnet 2
( 지온지압계 ) The Garnet - Biotite 지온계 The Garnet - Biotite geothermometer Table 27-2. Experimental results of Ferry and Spear (1978) on a Garnet-Biotite Geothermometer T o C Initial X(Fe-Bt) Final X(Fe-Bt) Final Final Final X(Fe-Grt) (Mg/Fe)Grt (Mg/Fe)Bt K T Kelvins 1/T Kelvins 799 1.00 0.750 0.905 0.105 0.333 0.315 1072 0.00093-1.155 799 0.50 0.710 0.896 0.116 0.408 0.284 1072 0.00093-1.258 749 0.50 0.695 0.896 0.116 0.439 0.264 1022 0.00098-1.330 738 1.00 0.730 0.906 0.104 0.370 0.281 1011 0.0009900099-1.271 698 0.75 0.704 0.901 0.110 0.420 0.261 971 0.00103-1.342 698 0.50 0.690 0.896 0.116 0.449 0.258 971 0.00103-1.353 651 0.75 0.679 0.901 0.110 0.473 0.232 924 0.00108-1.459 651 0.50 0.661 0.897 0.115 0.513 0.224 924 0.00108-1.497 599 0.75 0.645 0.902 0.109 0.550 0.197 872 0.00115-1.623 599 0.50 0.610 0.898 0.114 0.639 0.178 872 0.00115-1.728 550 0.75 0.620 0.903 0.107 0.613 0.175 823 0.00122-1.741 550 0.50 0.590 0.898 0.114 0.695 0.163 823 0.00122-1.811 601 0.50 0.500 0.800 0.250 1.000 0.250 874 0.00114-1.386 601 0.25 0.392 0.797 0.255 1.551 0.164 874 0.00114-1.807 697 0.75 0.574 0.804 0.244 0.742 0.329 970 0.00103-1.111 697 0.25 0.468 0.796 0.257 1.137 0.226 970 0.00103-1.487 lnk lnk D = -2108 T(K) + 0.781 ΔG P,T =0=ΔH = 0.1, 298 - TΔS 0.1 298 +PΔV+3RTlnK + D ΔH PΔV 1 ΔS ln K D = + 3R T 3R ( ) o 52, 090 + 2. 494P MPa T( C) = 273 19. 506 12. 943lnK Figure 27-5. Graph of lnk vs. 1/T (in Kelvins) for the Ferry and Spear (1978) garnet-biotite exchange equilibrium at 0.2 GPa from Table 27-2. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. D The Garnet - Biotite geothermometer The Garnet - Biotite geothermometer Figure 27-6. AFM projections showing the relative distribution of Fe and Mg in garnet vs. biotite at approximately 500 o C (a) and 800 o C (b). From Spear (1993) Metamorphic Phase Equilibria and Pressure-Temperature-Time Paths. Mineral. Soc. Amer. Monograph 1. Figure 27-7. Pressure-temperature diagram similar to Figure 27-4 showing lines of constant K D plotted using equation (27-35) for the garnet-biotite exchange reaction. The Al 2 SiO 5 phase diagram is added. From Spear (1993) Metamorphic Phase Equilibria and Pressure-Temperature-Time Paths. Mineral. Soc. Amer. Monograph 1. The GASP geobarometer The GASP geobarometer G: Garnet ( 석류석 ) A: Aluminosilicate ( 남정석 / 홍주석 / 규선석 ) S: SiO 2 ( 석영 ) P: Plagioclase ( 사장석 ) Figure 27-8. P-T phase diagram showing the experimental results of Koziol and Newton (1988), and the equilibrium curve for reaction (27-37). Open triangles indicate runs in which An grew, closed triangles indicate runs in which Grs + Ky + Qtz grew, and half-filled triangles indicate no significant reaction. The univariant equilibrium curve is a best-fit regression of the data brackets. The line at 650 o C is Koziol and Newton s estimate of the reaction location based on reactions involving zoisite. The shaded area is the uncertainty envelope. After Koziol and Newton (1988) Amer. Mineral., 73, 216-233 Figure 27-8. P-T diagram contoured for equilibrium curves of various values of K for the GASP geobarometer reaction: 3 An = Grs + 2 Ky + Qtz. From Spear (1993) Metamorphic Phase Equilibria and Pressure-Temperature- Time Paths. Mineral. Soc. Amer. Monograph 1. 3
Table 27-3. Mineral Compositions, Formulas, and End- Members for Sample 90A from Mt. Moosilauke, New Hampshire % Oxides Garnet Biotite Muscovite Plagioclase Wt. SiO2 37.26 34.22 44.50 64.93 Al2O3 21.03 18.97 34.50 22.59 TiO2 1.23 0.40 FeO 32.45 17.50 0.70 MgO 2.46 9.98 0.46 MnO 6.08 0.12 0.02 CaO 1.03 0.01 0.03 2.90 Na2O 0.27 1.64 9.36 K2O 7.79 8.05 0.45 Total 100.31 90.09 90.30 100.23 Cations Si 3.00 5.43 6.17 2.84 Al IV 2.00 2.57 1.83 1.17 Al VI 0.98 3.81 Ti 0.15 0.04 Fe 2.19 2.32 0.08 Mg 0.30 2.36 0.10 Mn 0.42 0.02 0.00 Ca 0.09 0.00 0.14 Na 0.08 0.44 0.83 K 1.58 1.42 0.03 Fe/(Fe+Mg) 0.88 0.50 0.46 Prp 10 An 14 Alm 73 Ab 83 Sps 14 Or 3 Grs 3 From Hodges and Spear (1982) and Spear (1993). Figure 27-10. P-T diagram showing the results of garnet-biotite geothermometry (steep lines) and GASP barometry (shallow lines) for sample 90A of Mt. Moosilauke (Table 27-4). Each curve represents a different calibration, calculated using the program THERMOBAROMETRY, by Spear and Kohn (1999). The shaded area represents the bracketed estimate of the P-T conditions for the sample. The Al 2 SiO 5 invariant point also lies within the shaded area. P-T-t Paths Figure 27-11. P-T phase diagram calculated by TQW 2.02 (Berman, 1988, 1990, 1991) showing the internally consistent reactions between garnet, muscovite, biotite, Al 2 SiO 5 and plagioclase, when applied to the mineral compositions for sample 90A, Mt. Moosilauke, NH. The garnet-biotite curve of Hodges and Spear (1982) Amer. Mineral., 67, 1118-1134 has been added. Figure 27-12. Chemically zoned plagioclase and poikiloblastic garnet from meta-pelitic sample 3, Wopmay Orogen, Canada. a. Chemical profiles across a garnet (rim rim). b. An-content of plagioclase inclusions in garnet and corresponding zonation in neighboring plagioclase. After St-Onge (1987) J. Petrol. 28, 1-22. P-T-t Paths Figure 27-13. The results of applying the garnet-biotite geothermometer of Hodges and Spear (1982) and the GASP geobarometer of Koziol (1988, in Spear 1993) to the core, interior, and rim composition data of St-Onge (1987). The three intersection points yield P-T estimates which define a P-T-t path for the growing minerals showing near-isothermal decompression. After Spear (1993). 변성상 (Metamorphic Facies) 특정암석이한정된변성조건 ( 온도 / 압력범위 ) 를지시하는평형상태의광물조합 단순한세종류의암석 ( 대리암, 염기성암, 니질암 ) 의변성온도 / 압력에따른광물변화를비교 비슷한온도압력영역에서서로다른광물조합이지속 됨. ( 예, 4kbar, 550 C) 염기성암 = 안데신 + 각섬석 + 석영 니질암 = 석영 + 규선석 + 백운모 + 흑운모 + 석류석 + 올리고클레이스 대리암 = 방해석 + 돌로마이트 + 투각섬석 + 활석 4
Metamorphic Facies Metamorphic Facies Fig. 25-2. Temperaturepressure diagram showing the generally accepted limits of the various facies used in this text. Boundaries are approximate and gradational. The typical or average continental geotherm is from Brown and Mussett (1993). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. 청색편암상 에클로자이트상 백립암상 Table 25-1. The definitive mineral assemblages that characterize each facies Table 25-1. Definitive Mineral Assemblages of Metamorphic Facies (for mafic rocks). Facies Definitive Mineral Assemblage in Mafic Rocks Zeolite zeolites: especially laumontite, wairakite, analcime Prehnite-Pumpellyite prehnite + pumpellyite (+ chlorite + albite) Greenschist chlorite + albite + epidote (or zoisite) + quartz? actinolite Amphibolite hornblende + plagioclase (oligoclase-andesine)? garnet Granulite orthopyroxene (+ clinopyrixene + plagioclase? garnet? hornblende) Blueschist glaucophane + lawsonite or epidote (+albite? chlorite) Eclogite pyrope garnet + omphacitic pyroxene (? kyanite) Contact Facies After Spear (1993) Mineral assemblages in mafic rocks of the facies of contact metamorphism do not differ substantially from that of the corresponding regional facies at higher pressure. 4 개의그룹으로변성상을고려하는것이편리함. 1)Facies of high pressure ( 고압상 ) Blueschist( 청색편암상 ) and eclogite facies( 에클로 자이트상 ): 고압의상태. 소규모산출 상대적으로낮은온도의 blueschist facies 는 low T/P gradients 에서발생. 특징적으로섭입대에서나타남. 에클로자이트가일반적인지온구배상태에서안정하 기때문에, 에클로자이트는심부지각또는맨틀에서 굳어진염기성마그마일가능성이있음. 2) Facies of medium pressure ( 중압상 ) 현재지구표면에서노출된 greenschist, amphibolite, or granulite facies. 3) Facies of low pressure ( 저압상 ) The albite-epidote hornfels, hornblende hornfels, and pyroxene hornfels facies: 접촉변성지역및매우높은지온구배의광역변성지역. Sanidinite facies는매우드물다. 4) Facies of low grades ( 저변성상 ) The zeolite and prehnite-pumpellyite facies are thus not always represented, and the greenschist facies is the lowest grade developed in many regional terranes 고압상 변성상계열 (Facies Series) Miyashiro(1961) : 변성대에출현하는일련의상들의연속성을변성상계열 (metamorphic facies series) 라부름. Fig. 25-2. Temperaturepressure diagram showing the generally accepted limits of the various facies used in this text. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. 저변성상 중압상 저압상 최초로인지된지역 : 영국의바로비안지역과부칸지역. 표식광물 (index mineral) 과등변성도선 (isograd) 에관한이해가필요. 5
Facies Series 1. 접촉변성상계열 (Contact Facies Series ;very low-p) 2. 부칸변성상계열 (Buchan or Abukuma Facies Series; low-p regional) 3. 바로비안변성상계열 (Barrovian Facies Series; medium-p regional) 4. 산바가와변성상계열 (Sanbagawa Facies Series; high-p, moderate-t) 5. 프란시스칸변성상계열 (Franciscan Facies Series; high-p, low T) Fig. 25-3. Temperature- pressure diagram showing the three major types of metamorphic facies series proposed by Miyashiro (1973, 1994). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. Orogenic Regional Metamorphism of the Scottish Highlands George Barrow (1893, 1912) SE Highlands of Scotland - Caledonian orogeny ~ 500 Ma Nappes Granites Barrow s Area Figure 21-8. Regional metamorphic map of the Scottish Highlands, showing the zones of minerals that develop with increasing metamorphic grade. From Gillen (1982) Metamorphic Geology. An Introduction to Tectonic and Metamorphic Processes. George Allen & Unwin. London. Orogenic Regional Metamorphism of the Scottish Highlands Barrow : 이질암류 (pelitic rocks) 를기준으로연구함. 변성정도가증가함에따라나타나는새로운광물들의출현에기초하여, 변성대 (metamorphic zone) 로이지역을세분할수있었음. ( 등변성도선-isograd-개념도입 ) 바로비안변성대에서전형적인변성광물조합및특징 Chlorite zone( 녹니석대 ) : 이질암들이점판암또는천매암. 전형적으로녹니석, 백운모, 석영및조장석을함유 Biotite zone( 흑운모대 ): 점판암이천매암및편암으로바뀜, 흑운모, 녹니석, 백운모, 석영및조장석함유 Garnet zone( 석류석대 ): 뚜렷한적색의 Fe-석류석 (almandine) 을갖고있는편암. 일반적으로흑운모, 녹니석, 백운모, 석영및조장석또는올리고클레이스를함유 Staurolite zone( 십자석대 ) : 십자석, 흑운모, 백운모, 석영, 석류석, 그리고사장석을갖는편암. 일부녹리석이남아있을수도있다. Kyanite zone( 남정석대 ) : 남정석, 흑운모, 백운모, 석영, 사장석, 석류석과십자석이있는편암. Sillimanite zone( 규선석대 ). 규선석, 흑운모, 백운모, 석영, 사장석, 석류석및간혹십자석이나타는편암내지편마암. 일부남정석이남아있는경우도있음 (although kyanite and sillimanite are both polymorphs of Al 2 SiO 5 ) 6
Figure 21-8. Regional metamorphic map of the Scottish Highlands, showing the zones of minerals that develop with increasing metamorphic grade. From Gillen (1982) Metamorphic Geology. An Introduction to Tectonic and Metamorphic Processes. George Allen & Unwin. London. Fig. 25-9. Typical mineral changes that take place in metabasic rocks during progressive metamorphism in the medium P/T facies series. The approximate location of the pelitic zones of Barrovian metamorphism are included for comparison. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. Buchan( 부칸 ) 변성상계열 이질암성분은비슷하지만등변성도선 (isograds) 및표식광물이다르다. 표식광물로비교 The stability field of andalusite occurs at pressures less than 0.37 GPa (~ 10 km), while kyanite sillimanite at the sillimanite isograd only above this pressure 변성도부칸 (Buchan) 변성상계열바로비안 (Barrovian) 변성상계열 저변성 녹니석대흑운모대근청석 (cordierite) 대홍주석 (andalusite) 대 녹니석대흑운모대석류석대십자석대남정석대 고변성 규선석대 규선석대 Figure 21-9. The P-T phase diagram for the system Al 2 SiO 5 showing the stability fields for the three polymorphs andalusite, kyanite, and sillimanite. Also shown is the hydration of Al 2 SiO 5 to pyrophyllite, which limits the occurrence of an Al 2 SiO 5 polymorph at low grades in the presence of excess silica and water. The diagram was calculated using the program TWQ (Berman, 1988, 1990, 1991). Petrogenetic grid for pellitic rock Figure 21-1. Metamorphic field gradients (estimated P-T conditions along surface traverses directly up metamorphic grade) for several metamorphic areas. After Turner (1981). Metamorphic Petrology: Mineralogical, Field, and Tectonic Aspects. McGraw-Hill. 7
일본의쌍변성대 (Paired Metamorphic Belts of Japan) 일본의쌍변성대 북서쪽변성대 ( 해구로부터멀리떨어져있는것 ) 는 Ryoke (or Abukuma) Belt. Figure 21-12. The Sanbagawa and Ryoke metamorphic belts of Japan. From Turner (1981) Metamorphic Petrology: Mineralogical, Field, and Tectonic Aspects. McGraw-Hill and Miyashiro (1994) Metamorphic Petrology. Oxford University Press. Low P/T ( 부칸타입의광역변성조산대 ) 변성퇴적암 ( 이질암 ) 이주로구성. 그리고 sillimanite zone 이상의등변성도선이지도상에그려짐. 전형적인고온-저압변성대이며화강암체가일반적으로다수분포 동남쪽변성대는 Sanbagawa Belt 이는고압-저온타입의변성대 료케변성대에비해서염기성암석이상대적으로많은것이특징. 글라코패인 (glaucophane; 고압에서만들어지는 Na-각섬석 ) 이많은청색편암이일반적임. 해구의섭입대지역 : 600 o C 등온선이 100 km 깊이까지유지됨 ( 저온 - 고압 ) 화산호인근 : 20 km 깊이에서 600 o C ( 고온 - 저압 ) Miyashiro (1961, 1973) suggested that the occurrence of coeval metamorphic belts, an outer, high-p/t belt, and an inner, lower-p/t belt ought to be a common occurrence in a number of subduction zones, either modern or ancient Contact Metamorphism of Pelitic Rocks in the Skiddaw Aureole, UK 화강암체가관입한 Ordovician Skiddaw Slates (English Lake District) Figure 21-13. Some of the paired metamorphic belts in the circum-pacific region. From Miyashiro (1994) Metamorphic Petrology. Oxford University Press. 관입체는천부에서일어났고, 첩촉효과는초기저변성광역변성작용과중첩됨. 8
Contact Metamorphism of Pelitic Rocks in the Skiddaw Aureole, UK Skiddaw granite 주변의변성대는세개의암석의조직에기초하여변성대로세분됨. Increasing Metamorphic Grade Unaltered slates Outer zone of spotted slates Middle zone of andalusite slates Inner zone of hornfels Skiddaw granite Figure 21-14. Geologic Map and cross-section of the area around the Skiddaw granite, Lake District, UK. After Eastwood et al (1968). Geology of the Country around Cockermouth and Caldbeck. Explanation accompanying the 1-inch Geological Sheet 23, New Series. Institute of Geological Sciences. London. Contact Metamorphism of Pelitic Rocks in the Skiddaw Aureole, UK Intermediate zone: 완전히재결정된점판암 흑운모 + 백운모 + 근청석 + 홍주석 + 석영 Figure 21-15. 15 Cordierite-andalusite slate from the middle zone of the Skiddaw aureole. From Mason (1978) Petrology of the Metamorphic Rocks. George Allen & Unwin. London. 1 mm Contact Metamorphism of Pelitic Rocks in the Skiddaw Aureole, UK Inner zone: 완벽하게재결정, 엽리가사라짐. 1 mm Figure 21-16. Andalusitecordierite schist from the inner zone of the Skiddaw aureole. Note the chiastolite cross in andalusite (see also Figure 22-49). From Mason (1978) Petrology of the Metamorphic Rocks. George Allen & Unwin. London. Petrogenetic grid for pellitic rock Fig. 25-3. Temperaturepressure diagram showing the three major types of metamorphic facies series proposed by Miyashiro (1973, 1994). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. 9
Pressure-Temperature-Time (P-T-t) Paths Metamorphic P-T-t paths may be addressed by: 전진변성과정과후퇴변성과정을종합적으로정리하여그지역이어떤변성작용환경에놓였는지종합적으로판단하는것임. 광물의조합, 선후관계, 조직, 지온-지압계등을종합적으로정리하여판단하는것임. Fig. 25-12. Schematic pressure-temperature-time time paths based on heat-flow models. The Al SiO 2 5 phase diagram and two hypothetical dehydration curves are included. Facies boundaries, and facies series from Figs. 25-22 and 25-3. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. Fig. 25-14. A typical Barrovian-type metamorphic field gradient and a series of metamorphic P-T-t paths for rocks found along that gradient in the field. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. 10