Geothermobarometry of metapelites of southwest · PDF fileGeothermobarometry of metapelites of...
Transcript of Geothermobarometry of metapelites of southwest · PDF fileGeothermobarometry of metapelites of...
Geothermobarometry of metapelites of southwest Mahneshan, using multiple equilibria curves and
THERMOCALC program
A. Saki, M. Moazzen, M. Moayyed
Department of Geology, University of Tabriz, Tabriz, 51664, Iran Email: [email protected]
Abstract: Pressure and temperature of metamorphism in the Mahneshan
area were estimated in order to determine the type of metamorphism and
tectonic setting of the rocks. Biotite, muscovite, plagioclase, garnet, quartz,
andalusite and staurolite minerals are crystallized together in metapelites in
the regional metamorphic rocks of southwest Mahneshan. Chemistry of
coexisting minerals is studied using microprobe analysis. Using multiple
equilibria calculations and THERMOCALC program, temperatures of
~520°C and pressure of ~3 kbar have been calculated for the formation of
these rocks. Using these data, geothermal gradient of 60 °C/km has been
calculated for the upper crust of the Mahneshan. Based on calculated
geothermal gradient, the Buchan type metamorphism is suggested for the
metamorphic rocks of southwest Mahneshan.
Keywords: Geothermobarometry, metapelites, Buchan type, multiple
equilibria, Mahneshan, THERMOCALC.
Vol. 12, No. 2, 1383/2004 Fall & Winter
(Received: 19/02/2004, received in revised form: 05/08/2004)
��� ���� � �� ���� ��� ������ ��������������� ����������� ���� �� !� �"� ���� #$����% �& #��$��
'&�(����
�(�� )�* +� ,- �. /+� ,- ��0.
����� �� �� ���� �� ������� ����� ���� ���:[email protected]
�12%: ��! "#$� %&'( ) (#�* +#� �� ,�-��� +���.� � ��#� �� /#� ��� � �0�1��2�� ��3�� ,�� � "��4 ��-��� 5�6�� ���� �7� %���1 �-��� ��#� �.
9���"�� ,�-��:;9#�<;� :��#6�:���#�& :����"���� � ��#��7�= ���"�#9�7�� � "� >. �& �7� "#?�� +���.� ( ) (#�* ��#� �� ��" ,�-���7�� .�& ����@. ,�-���9 �@��
AB� (� �� 6�� �����= � ���C����7.�� & � ���C��� �&' � D��9#�"��4 5�6�� ��� �-���"���7E F,�� � "�&#?�9 5�6�� �-�= "���7E GHI *"� '%���1 �� ������ �7.
� �� �& �7� %���1 "��4 � �� & %9 ,"��4J���� ���"�� ������ :6�� � ���#�& '& D���<� ��%%&�� �7= ���7�� .���� ��� � ���C��� �&�.�+���� � ����KI*"� '�� ������
& +���.� %��#� ,� & �#?�9 &%7= ��� .+���� � %& %*#� �&���& �%�7= ������� �7� %�4 � $� "� +���.� ( ) (#�* ��#� �� ,�-��� ,� & +�9�& /#� ��#� ��.
�����145 ��� :, ��"�&# �#L<���#� �� ��" ,�-��� �+�9�& , ����1� ���� � ,�.M%���7� �+���.� �D��9# �.
N"�@� �>.���� O��H�+��� � ��L��PF'1CQ � �RST��RUV
)%��X �4��"�UV/SS/ZFPH����-� %B�� �4��"� S[/T/SU\U(
"� �7� +#� �� ��" ,�-��� , ��"�&# �#L< ... HZ^
#��6� �� ��! _?)� �� � %9 "� �� `"#Q ��#� �� � �� �-* "� /;a��"��4" �� ��2�� �
��2��"�� ���b� �'��� �� .�2��� 0�1 �� ��2��>9�E � � %& %*#� �&,��#� �����@.� �L�E ��� .ca�� � �6�_��* "��� `�X�X1� /#� ��� ������(#�*
� +���.� ( ) (�6� d#�"�-M��� .��XX1 `�X�X1�e?�B ��� +��� %��b� "� ���� %X!� ��� %9��B& +� �� f�� �� � ���%9gh�@�E� ��� +#� �� �� ��9 � +� "� �
���'��#� �� ,�9 +� �� ,�.��� ]Z[."� %�4�� +#@�2" ,�-��� X!�'% ��! �"# � 5�� ������� � D��&� ����� D��& ,�-��� ��-��6�?�� D��9 ��7� +#� �� ��" ,�-��
�. ��7��/#� ,�-���� �� �-���� �S�I7���.)56�Z.(� i� %�#@� ��� 1Q ,"�� & ,�-��� ���"X ����#6�� 6� j�� ka ,�7 � ,� &���9 `� ��! �?6� �� � �����
%�-��7�7.<�"�� il�7� ��� � �-��� ��� "� �-���9 �� �� �?6� �� m���"� "#?��AB� �-��;&� �4"#� �7]H[.,�-�����"%�4 � "� n % ��! �"# %X!� ��� "� %9 7��
�6� � 7��"��o ��"�� ����� ����������"����:��#��7�= ���� . ��! �&'��#6�� 6���j�� ka�X�� �-���9 ��<�"�� �.�����������"�� ,�-��;&� �4"#� m���"� � ��#��7�= ��� � �?6� �� ,�.�4 �& ����"����7�7� .� ���C��� �&J������"�� ������ :
���#�&�,�� °CGZI7� AB� ��#� �� 3�� ,� & ]F[., �#�l�9 %�� & � ���C��� �&D��9# � ]p["��4 "���7E F�&#?�9 "�� �"���7E °CGHI 7= ��� %& ]H[.� �� "��4
�7� %���1 ��� ,�-��" � �7= ��7& ���X �&7�"�� ���#B@. .
72�8"� e?�B ��#� �� ,�-��� k�#� q��@� X!�'+���.� ( ) (#�* .
7�r �+sr ��t�� HZP
�� ���� ��� ������ � �42��� ��! �&' �� �4 �� ��7� +#� �� ��" ,�-��� �?6�D1�D2�-��� ��� "� �������
7�7�]G[.&%,"#a %9D2� D1� ��#& ��#n u�,�. D1�� & ��& � �"�# � �v & "� �"��� .%9 ,7.�#��#*� D1� �&�u �" 9�� 7��"��o 7�:%��#���� ,���X& �#*�S1+�"�
���� ���"�_��) S2���"#2 ��M �S1 u� "� S2.+��@. �&D15�� +#� �� ,�-���9 ��"�#9 ���#6� ����#�& �����"���� ���"����& ;9#�<;� %7�� �7= �#*� .+#� �� �4 ���M1� �7��� �#� .i��?6� �� �4 � D1�4 �?6� ��D2� �1� �" %X!� �w��#� �� � ���� "� n �uM2��� %�4 ��� ��#��7�= +� �� .
���� ���"��)%X!� "� _��S2���,7.�� �#2 %9 ��� &�#*� D2)56�H.(��#� �� �a �7� 5�6�� ,�-���9M1��#� �� "� M2��#& "�7��� ��� ���� �� � � 7��
�#� �@� �7�� �-���9 ��� "� �7��" i� ���9�� ,�-�4�& �.3�� ,�-���9 ��<�"�� _�� � ��7& ��#� ��� 7��"��o�7�= �����"���� ;9#�<;� � ��"�#9 ���#6� ����#�& ���"�� ���#�.
���� :����$���� �����(�� � �0�1$�( ���$�! O#a#��7�= ���9 ,��E ���� %�#@� "� �7� +#� �� ��" ,�-�����%& x��� X�H �@����� � ��"& � 7�-�= � �2 � �7�� � �� f�" %& ��4� � �#*� 5��� %& 7�#� .��"�� ���� "�
��� +���@� � %& ���� %�#@� .( ) (#�* ���?��� ,�-��� "� � ,�-���9 %o#@y�7� %�2��� +���.� 7�� )� ,"�z�2� >�;ok* ]K[�7� %�4 � 7��(:
Bt+Ms+Qtz+Kfs (1) Grt+Bt+Ms+Qtz+Pl (2) St+Grt+Bt+Ms+Qtz+Pl (3) And+St+Grt+Bt+Ms+Qtz+Pl (4)
� �7�� ��;&� �4 � `"#z& �-��� ��� "� ��#��7�= ���9 �7��9 `"#Q %& ��"�#9� �#��%�����" ��& "�#���� %�4 � "� n ���#�& ,�. .� ��#& 56� +�7& ���9 ��� �*# ��#�2
�"�� )56�H(.56� %@�� �� 56� +�7& ���#�& & ��#6� �� @. %& "�� %�7�"�= �#*�����-��"�� _?)� %�#@� ���. .��#��7�= 56� %@�� ,�."#?& ,�"�� �. � ��#& ��"� � "�� � �2 &
�-�= � %& �����7� %��y�7�� .56� ,�."#?& ,�"�� ����"���� 56� %@�� �� "�� � "����� %��"����.�& � ��a "#� "� ��#��7�= � �7�� f�" >9 ��"#Q �� f�" �#� .��#��7�= �.,�"���L#� �4�& #?�9 � �� ,�-���9 � ���-�#�#?6�� �& D���;&��.7�.�.�� � �� ,�-���9 ���
���9 52�� "�& �-��� "� ��"�� ���� %& %&�� �" �Q�2 �-* ��#��7�= %��"�= �#*� 7��.56� %@�� ��"�� ,�."#?& 56� �� "�� ��#& "���,��E �.�� � 7�.� @. ���#�& �& gh#@
��"�#9 ,�-�#�#?6����.7�.�7�� N�-��"�� "���7E G/I��H �@�?� ��� .%& %*#� �&
"� �7� +#� �� ��" ,�-��� , ��"�&# �#L< ... HZ{
7� % ��! ,�.��<�"�� +#� �� ,�-�� �+���.� ( ) (#�* ���?��� ��#� �� ,�-��� "� �%�4�� d ��� �-��� ��� "� �7��.
72�;,"#� |#��� �� ���z�%�#@� ��.��E�� +#� �� ,�-��� � '+���.� .e��(��"�� ���� S1��"�� D� "� :%9 ���� ����"����%?��� %& S2�}�� ��"#}2 ��}M .Bt(II) ~�� �?6}� �� "�
��� �7� 5�6��.((~�� �?6}� �� �}4 �uw}� �?o %& ����#�� 9 <�#�?9 5�6��.|(�}4�& `��}C� �B& �" � ��) ,�-)����}� �}M �@� (��}B& ��"�#}9 � �}�) ,�-)h�}& �}��" �@}�(`(7}�"
O�� %?E �?6� �� �& +��@. ����"����.�(/�@�*� 7�" ���#�& � ��"�� q�}� ~�� �?6}� �� � .3(!&�" '�?6� �� �6� � ��) ,�-��� "� ~�� � O�� ,�..
<&� �
= >
? @
7�r �+sr ��t�� HHI
8AB1��1� �! ���9 %o#@yBt+Ms+Qtz+Kfs ����� �*"� ��'(#}�* ���?��}� ,�-��}� "� ��#� ��
� +��� �" +���.� ( ) 7.� .����� gh�@�E� �-��� ��� "� ���#�& "#-��&q�9�� `"#Q ���� %�4 �:
Kfs+Chl = Bt+Ms+Qtz+H2O (A) ���#�& "#-� ,� &�����"���7E F^I ��°CpII �}�� �7}� %�4 � $� "� �� ����� ��� "�
]^[.� � &�� ���9�� ���M O�� � 0�� �XFeO ��� ]P[.
;AB$��� �! �������"�� +� ,�-��"�� �+= 7�" gh�@�E� � ��� ��7��@�= � +�#& ��) �&%�}�#�� q�}9�� ���� �� @.:
Chl+Ms = Grt+Bt+Qtz+H2O(B) o#@y%���9 Grt+Bt+Ms+Qtz+Pl ���� ��@.� ,�"�� ���?� ,�-��� "� ,���� .��� � �
"� ���9 %o#@y N�&�� ��� � ,������ "�7��� +#� �� ��" ,�-��� "� .�-��� ��� "�,h�& "�7XMnO �CaO� �o�& � �@9 ,�� "� ��"�� %9 �#� °CpGI�#� .�� �"�
�@9 "�7X �& ,�-��� "� %9 ���EMn �Ca�� �h�& ,�� �� ��"�� °CGII�@� .�� �#� ]{[.� ��"�� � >$��� �� ����� D� ��-��� 59 ����@�� _�9 � `��C� �?o %& ��� &��& � 1Q "
� �7.�� �#� .� �7.�� �-��� �v & ���� +#@�2" "� ��"�� #�� � ��� �v & "��@� �7�� �#�.
CAB1&������ �! ���}}9 %}}o#@y St+Grt+Bt+Ms+Qtz+Pl %}}X!� �}}�" ,�-��}}� "� +� �}}�� ���}}��@�
+���.���� .� �@� .�� 7�L#�� ?9 �-�= "� %9 ���?��� ,�-��� "� ����"���� �#�&q�9�� & � %� �#*� 7�= ]ZI[:
Chl+Grt+Ms = St+Bt+Qtz+H2O(C) � �1� q�9�� ���w"�7X �uMnO�"�� "� n f�� "� �#*# ]{[.D� ,� & "#&� q�9��
� �" ,"��4 . "� ��&�u ,�� 7.�]^[.�" ��� � %��#���� q�9�� D� ��� %��� ��� �� �� %� � �6� %9 7&���#� ~�@� ���9�� .X!� "�'�o�& �� ?9 +7� ~�@� % ��! �"#
��� �7� q�9�� +7� 5�9.����"���� %9 ����&� ��y�� h�& q�9�� #�, ��� q�9�� �(D) f�� "� ��� �"
�7.� %9 _*# �4��� ����"���� 7� 7.�#2 .%�h "� q�9�� ��� `�6�?��#?�4 � ��) ,�.� ,�" 7.�]ZZ[:
Chl+Ms = St+Bt+Qtz+H2O(D)
"� �7� +#� �� ��" ,�-��� , ��"�&# �#L< ... HHZ
DAB0!�&��$E �! ���9 %o#@y And+St+Grt+Bt+Ms+Qtz+Pl 7��9 AB�N+� ��� ���.��#��7�=
gh�@�E� +� ��� "��&��� �7� ��y�� � q�9�� :Bt+St = Grt+And+Ms+Qtz+H2O(E)
�4 �� ���& ,�"�� +� ��� "� �-���*"� �� �@9 �',��= ��.7�.&�?o ��@. %,�-���9 +� ��� "� �#*#'?��� %&(� �� 6�� %��y� �7� 7��� ����� �.,5Q�E "��@�� �-���9 �
��� �7� ���C��� , ��"�&# �#L< .
�F1���1$�( � �� c�n� ��� � ,� & %o#@y ��� "��4�� j�� k!X %� ,�"�� %9 ���-��� � �?X�Q
,�-���9 �� ���& ��#� �� 3�� ��.7�)%�#@� ,�.AS13A-AS13B-AS13F(%&d�" ?��� %& (� �� 6�� +� �6��'������ CAMECA O7 SX100�X�X1� #������ "� ~#?o ��
���� ������� ������ � 7�7� %��y� +���?��� `����1 ,� & �����@a� 5&�n ,�.& �6�����# � %7= ���.���E "� ������ ��� wavelength dispersive � "�9 7�9 .
(��� <����%��"�& &� & �7� ���C��� ��� �6�� kvZG %!X� . ,� & %��y� +� �pI%���u ��#&��� .'��y� ,� &%�#@� �`7� %& ���� * � nAF���C��� �7.� � ��a ,�.�"�7����� �
,� & �o#�z���[email protected]� ���C��� ������ .������ ,�!2"���7E Z%±7��9� `"#Q %& Q��o��� .q�� ���1 � '� �� "��4�� �-���9 ����@�� _�9 � ��" & %& >��� �.
G1(��1F1� �0� B$��� O�7*Z%��y� %�#@�"� ��"�� � ,�. ,�.�7� %��y�� +��� �" 7.� .��"�� O# 4& ����ZH��� �7� %���1 +���9� >�� .7��9� /#@y� ,�. ��& ���9 ��PG/{{ ��{^/ZII�
�"�7XTi��� >9 �?�2 .��"�� �7� %��y� ,�."��#@� `"#Q %& ���� %� Mn+Ca�Fe2+�Mg56� "� F�7� ���� +��� 7��.�#@� %� . "� ��"��'O#?1 �_�9 � ��1� � �7� %��y�
+7��@�= 7�* :���"��l�� "� %t ��� ��7E ZI7Q"� +=��� ���"��l�� .
G1(�� 1F1� �0�B1��1� %��y� ��� ���#�& � ,�. "�O�7*Z� �7�� 7�#� .���� & ���#�& O# 4HH+���9�
��� �7� %���1 . &56� ���� p����#�& _�9 � ��71 "� �.N���= :���#�#?4 "� n� 7� ��.
G1(��1F1� �0�!H(�0�HI %��y� %�#@� "� ;9#�<;� � ,�. ,�. AS13B �AS13F O�7* "� Z��� �7= .O# 4
���� & �.;9#�<;�P��� �7� %���1 +���9� >�� .;9#�<;� "� ����= ��# �9&%
7�r �+sr ��t�� HHH
`"#Q XAbPl= Na/(Na+Ca+K)=0.8 ��� ."�7X �.;9#�<;� 7�"�� #�"� � ���"#�= �@9
)56�T.(
G1(��1F1� �0� �1�� ��21� %��y� �� 6�� ,�.�#@� %� "� 7�C� ,�6� (�'AS13A-AS13B:AS13F O�7* "� Z�7= 7�� .,� & 7�C� ,�6� O# 4HH��� �7� %���1 +���9� .�.�6� ,�.7��9� /#@y ��&pp/{F��FF/{^ ���.56�K>��X� �6� ,7�& 7�C� ,�."�"��#@� SAF �"+���� 7.� .�6� �7� % ��! ,�. ���&��#6� 7������ >9 "���& ������;� ���-��� #vo .
)���8%��y�+���.� ��" ,�-��� "� �#*# ,�-���9 (� �� 6� ,�..AS13FAS13BAS13AAS13FAS13BAS13FAS13B AS13AAS13FAS13BAS13AAS13FAS13B AS13ASample
Ms MsMsPlPlPlStStBtBtBtGrt(cor)Grt(cor)Grt(cor)Mineral
pZ/pKp^/pKFF/pK ^K/KGHF/K^ GF/KKFH/HK p^/HGGH/FpFp/Fp pH/FppP/FK {G/FG PK/FG SiO2
H^/IH^/IFI/III/IIZ/III/IFP/IZF/IHG/ZFK/ZpP/ZIK/II^/IIH/ITiO2
Ip/FGHK/FGFH/FG KF/HZ^G/HI pZ/HZ{/pG PH/GpHF/Z{KG/Z{ PG/Z{GG/HI FI/HI F/HI Al2O3
PI/IKZ/IKG/III/III/III/III/IHZ/ZZI/PPZ/^pI/^pG/ZpG/ZpZ/ZMgO
Ip/IIp/IIK/IGP/HGF/ZHp/HGK/III/II^/IZH/III/IIH/ZKp/III/ZCaO
II/IIZ/III/IIZ/III/III/IGZ/ZF pI/IHI/IZ{/IZH/Z^/ZI ZH/ZI P^/PMnO
{Z/ZPG/IPH/II^/IIP/II{/IGH/IFI/ZpHZ/HHPF/HZ ^F/HZGF/H{ IP/FZ{G/FZ FeO
II/III/IIH/IIZ/III/III/IIZ/I^I/IIP/III/IIZ/IIZ/IIZ/III/IZnO
ZI/IZI/III/ZH^/ZIIH/ZI KF/ZIII/IIZ/IZp/IFH/IZZ/III/IIG/IIF/INa2O
{H/PPK/P{I/PIp/II{/IIp/III/III/IIH/PZI/PH^/PII/III/III/IK2O
DJ/LDDD/LCC8/LCM/8NNMO/LL8/8NN CC/LMC/LM 8M/LDNJ/LDPN/LCPO/LLM;/LL DM/LLTotal
���� &ZZ
+���9�
���� &P+���9�
���� &HF
+���9�
���� &HH
+���9�
���� &ZH
+���9�
ZK/KFF/KZ^/KK^/HP^/HP{/HGH/Fp^/FpG/GFH/GpZ/F{H/HII/F{K/HSi
IF/IIH/IIF/III/III/III/IIF/IIp/III/IZK/IHI/IIP/III/III/ITi
K^/GFG/GKF/GZG/ZZZ/ZZZ/ZKK/P^p/PGI/FKI/FGI/F{H/Z{^/ZII/HAl
I{/IHI/II{/IZP/III/III/IHZ/IZ{/IGK/ZPI/Z^Z/ZIH/ZZP/IZP/IMg
II/III/IIZ/IIP/IZF/IZF/III/III/III/IIH/IIK/IIZ/IIG/IIp/ICa
II/III/III/III/III/III/IIK/IIG/IIH/IIH/IIH/IIZ/I^I/IGK/IMn
I{/IZF/IZF/IHP/III/III/IGZ/ZGp/ZKH/HPF/HKG/HG^/ZZp/HHP/HFe
II/IZF/III/III/III/III/IIG/IIP/III/III/IIH/IIZ/III/III/IZn
H{/III/IHK/I^p/IP^/IP^/III/IIZ/IIH/IZI/IIK/IIZ/III/IIZ/INa
GG/ZGF/ZGI/ZIF/III/III/III/III/I^K/ZKI/ZpP/ZI{/III/III/IK
PO/8CMC/8CMP/8C8C/ONN/ONN/ONP/8D NL/8DLO/8DCO/8O;M/8OCM/PND/P8N/PTotal
"� �7� +#� �� ��" ,�-��� , ��"�&# �#L< ... HHF
72�C,�. ��"�� ����@�� _�9 � "� �7� % ��!"��#@� ���� %�
Mn+Ca�Fe2+�Mg.=+7��@�,"�7X � ��� ���-� #vo �� �@-
�"�� �#*� ��� ���"��l�� � "h#�� �.
72�Q���#�& ����@�� _�9 � �. "� n ���#�#?4 � ���= _!n �� ��& %9
7�"��.
72�R����@�� _�9 � q��@��� %9 �7� %��y� ,�.;9#�<;� +�
���-� #vo 7.� �����=���& �� �"�� �" "�7X .
7�r �+sr ��t�� HHp
56��,�.�6� ����@�� _�9 � ,�. %�#@� "� �7� %��y� 7�C�
+���.� ./#� � g��7@o 7�C� ,�.�6�7���. ��#6�.%t �#� %*#� :
F: (FeO+MgO) RS: SiO UORA: Al
������$�� !� �S����1T��( U&�5���� ��������������� ���� ,�-��" �� �@- � �6�, ��"�&# �#L< ��1� � ���C��� ,�-���9 ��& %���7�M ���� � ,�.
f�� D� "� �#*# "�"��#@� P-T��� .d�" ��� "��7�&� q�9�� �" ��#� �� ,�. ���� "�� ,�-���9 ��7 � �� �h�& %9�"�� �" ����� ���9 O�� � ���E "� +#� � )����� *"� �� �'
,��= (�7���>��t.�-���9 ����@�� _�9 � � ���C��� �& il� )J���� %��y� %?��� %&(� �� 6�� (��1� �" q�9�� �7�.� +��� ,�."�"��#@� D� P-T� �� 9 >�" � ���C��� �&
���7�#����1� �.����"��4 �"� ��� %& =>�"� .q�9�� ��" & ,� & ���1 � ���� � ,�.'%�� & ���#� �� ,�� � "��4 ,�. , �#�l�9 �C?�B"�� �#*��7.%9 �y��" , �#�l�9 %�� &
"� � ��� � &"�9����� f�� %�� & �"�� +#� �� D��9# ����%tN��� ,�"�� �������# �,� & ZHF ���-� #vo���.a ,� &�� & �E� 'D��9# �]ZH[c�n� � �� �
��� ,� & �6@ ���X �6�����# � ,�.�5�� :�, �b� >9� � ���# >yE ���� ��= , �b� m����������� � ��4 ����C��� 7���� ���l����= �"�7����� ���E 5�6�� ,�.
n�7E d�" � ���C��� �& ���-� ,�vo� ~�@� ,� & Q��o � �7�7� ��1z� `� & 5��� �.���� �.,D��9# ����� �& g��@� f�.�@. �& y� ,�.7���. .`����1D��9# ��&� ���C��� ��� 'S �(�B��� �& �� "��4 ���X ��� ~�y�� �� � ��.,�."��4 ,� & %9 `"#Q ��7& "�,�� ,� & �� � AB���"��4 ,�.AB� ��1� O�� � ,�.��� %���1 q�9 �#� ."����� c�X1� D��9# �'B�� p/H��� �7� ���C��� .
0 = ∆G0(r) 1,T (P-1)(∆VS+∆αV)(T-289) ∆(βv)P/2+niRTlnƒi+RTlnK (1)
%��� ��� "� ∆G(r) �q�9�� i��� ��= ,< �� `� ���� ∆VS�7}�* ,�}.�4 >yE ���� αV
m����� _� � , �b��� ���βv_� }� ���� �}4 R��}.�� �}&�u ƒi�}4 %��}���#4 �"�}��K�O�� � �&�u n��7 � � �-�#P�T� "��4 _�� � %& �� 7���. .,� &�"�= & %}& "��4 � ��
D@9D��9# ����B� �-���9 ���-� ,�vo� %��#��9� %}��y� � ���C�}�� �}& (� �� 6��} ,�}.
"� �7� +#� �� ��" ,�-��� , ��"�&# �#L< ... HHG
%���17�7�.� � �}��#�& ,�}-���9 %��#��9� ,�-�7} �}& �}�"� "� �7}� %}L�"� ]p[�]ZF[������ 4 �& ��#6� ���9 O7 ]p[��� �7� %���1 .� D��9# � � ���C��� �& il� �}��� 4
���-� ,�vo� "�-M q�9�� ������� �7�7�:fSt + Qtz = Alm + And +H2O {1} Alm + fSt +Ms = Ann + And + H2O {2} Ann + fSt + Cel = Alm + Ms + H2O {3} fSt + fCel = Alm + Ann + And + H2O {4}
"� �����9����- f7�.� +��� N�.= ���-� ,�vo� �9 "�� �-����� .O�7* "�H�P�Tm#& . %& %9 �-��9�� � D� �&7� %���1 D��9# �7���7=��� . &���� ��� ���� �.�51
�" �-��9�� � n��"�"��#@� P-T >�" t��>��.�!2 "�7X ,q�9�� . ,�!2 � 7� %���1 �?9��J��"��4 ���� �4 � "� n $� �"# 7�.56�^��71 N, ��9�2� ��� "��4 � ��
� +��� �" +���.� %X!� �7� +#� �� ��" ,�-��� 7.� .�7� %���1 ,��"�3�� ��#� �� "���7E °CGHI �7� %���1 "��4 �"���7EF��� "�& #?�9 .���� ��� �& �.J������"�� :���#�& ]F[J�� "��4 �GPMB ]H[7�"�� 5�9 ���#B@. .
)���;5E%��� S�� ,� & )°C ( �� D� � ,�."��4 ,�� %& ,�-��9�� ,� & "�&#?�9 ��Z��p.P (kbar) 8 ; C D O J M P L 8N sdT sdP
q�t��S p^Z GI^ GpH G^K KZZ KpG K^{ ^Zp ^GI ^PG ZK pK/Iq�t��H pIG p^{ GGK KFP ^HG PZP {Z{ ZIFI ZZGG + PI PH/Iq�t��F GKZ GpP GHF p{H pG{ pZK FKG FZH HGG - K{ Hq�t��p p^G GHF G{I KKZ ^Fp PZZ P{F {PZ ZI^p ZZ^G ^p {F/I
)sdT:"�� �� 1�� ����sdP:�� +��� �" "��4 "�� �� 1� 7.�(
V �B���� � ��!'� +��� +�y� +���� "� +���.� ( ) (#�* +#� �� ,�-��� � �-��� ��� %9 7.�?E �%
?E �� � �?6� ��%�� 9 %& y� �" ��#� �� 7�� .���-���9?E "� ����"���� � ��"�� 7���'O�� ��#� ��)�?6� �� �(�7� 5Q�E 7�� .��4�& ,"�7��� %& %*#� �&)�6�����# � %y��� "� �(,�-���9
?E ��#� �� � 5Q�E'O�� �a-��� ��<�"�� � �~�� %?E ��#� �� ,� & �-���9 ��7 � �� �h�& �& ��� � �-���9 ����@�� _�9 � �̀ ��!� �� �"�= &7� ���C��� ��#� �� "��4 .�7� %���1 "��4 "� ��7E
F� "�&#?�9 ,�� �7� %���1 "���7EGHI��� �� ������ %*"� .��4 � $� "� �& ."��4 "�&#?�tO�� P/Hc@o �#?�t �#� ,�-��� ,� & %�� "��4 ,�F"�&#?�9 ��-��� 5�6�� c@o "���7EG/P
��� ��#& �#?�9 .��� ��h�& %��#� "� ��#� �� ����� c@o ��� .>��X� �&,�� 5Q�E )GHI %*"� �� ������ (c@o &)G/P �#?�9 (��� � �� +���� � "� ��7Ekm/°CKI&%� ���7�= .���
��� � �� +���� �� �� �&o#� ��#�,��h�& :����� "��4 (HT/LP)�"�� �X&�! ]HH[.
7�r �+sr ��t�� HHK
72�M,�-��9�� 51 Z��p"�"��#@� P-T .��71N��#��7�= ,"�7��� :����@�?��:,� }& �����9 ��� �7� ���� %���X .��71N"� �!2 +��� ���� & %9 , ��9�2 �v�& �7}� >�" , ��"�&# �
���� ���N�� �X!� ,�-��� "� ��#� �� 3�� "��4'� +��� �" +���.� 7.� ."� �� ��7EGHI "��4 � �� ������ %*"� "� ��7EF�}�� "�&#?�9 .�}X4� 0}2(GPMB) "��}4 �}�"��:;9#}�<;�:
��#6�:�?�n `� ��! � �" ���#�&]Z�H[� +��� 7.�.
d ����%�E�� ��#� �� ,�-� �-���9 ��<�"�� � +���.� ( ) (#�* ,�-��� "� ,� ca�� +#� �� ,�-��� %&��Calabria ������� (#�*"� ]ZZ[+� �Moldabian ,���"� "�
,�9 ]Zp[+#� �� ,�-��� �Saxothurinigian-Moldabian���"� "� ��]ZG[.%�E�� +#� �� ,�-��� ����@. ( ) (#�* ,� $� � +���.���56� "��4 �, �� %���
%& ca��Abukuma ���< "� ]ZK[�Buchan 7�?��6�� "� ]Z^[��� .,�-��� `��C� �-�� %X!� �"# ca�� +#� �� ,�-��� �& % ��!Abukuma �Buchn����9 �#*� ~7o
��� +���.� ,�-��� "� �� �� 9 . ��� `� ��! %����]ZP[� �� 9 �#*� ,�-��� "� �%�E�� ��#� �� ��.�� %X!� 7��� "��y ca�� "� ,�� +��� �" <� 7.� ._�� � ��7&
� $� "� �& +�#�4 � %X!� +#� �� ,�-��� ��7� %���1 ��� � �� +���� � �� /#� O�� �" +���.�Buchan�4 � $� "� ."#vE ~7o �� � "#vE %9 ���� %*#� 7��&
�� 9 ���9�"�� ����& %���� f�� ����@�� _�9 � %& ���&%0�� � >) �?o %6�"#a�@� "#?�� ���9 ��� ~#���#�= � �X4 � �.= � ��) ,�-��� "� �_��� �6�����# � �#�
]ZZ[.��.�� %X!� ,�-��� "� �� �� 9 "#vE �" +���.� ,�-��� "� += "#vE ~7o � <�
"� �7� +#� �� ��" ,�-��� , ��"�&# �#L< ... HH^
��@�� _�9 � `��C� %& +�#� 0&" %X!� �� ��� "� %���� f�� ������ .�� �"# "�X!� "� ��#� ��'���� +���.� �� ,�. ���� ��� "� �&�������� �� %& %*#� �& ���
�& � %X!� %*#�� %& m#& ,�-��� %9 _?! ��� %&X!� "� O�� +�"�� 5���� ,�.7��'+���.�)�� ����.�� %X!� <�(��#��� 7����7�� +#� �� %���!?� � 7�� +�#��C� %9
��#� �� ��q�� �� ��9 � )��� ��9 � (��� .�7��& ��"� _?! ��� %6��"#Q "� �����" & ��#� �� �,��h�& �+���.� %X!� ���n#4 %��#� "� �� ��9 � +� "� ����� "��4
� +��� �" 7.� .��#� ��,��h�& �� %& ����� "��4� `"#Q � 5�h� � �6 � ��:Z:j�� 7�+%��#� ,�Z]Z{[.H:,��%�E�� 0�#� �� >9 c@o "� �-�#�#?� � �.� � s#C� � 5Q�E ,� ]HI �HZ[.F:�"�n ~��z� � �@. ,�. "� �..
�"�n ~��z� 0�1 "� %9 h�& �� 0�#� "��4 ,�-��#� �� �#�� %& %*#� �& & ,� %�#*�� %& �7��=�"�n ~��z� 5Q�E +���.� +#� �� ,�-��� ��� O�@�E� �� ,���7�.��� &��&�
& ��"� +���.� %X!� +#� �� ,�-��� 5�6�� ,� & ~#� O7 %�@� $� 7�" .��#� /#� � ���.7�L#���� � %9 7�"�� �#*� +���.� %X!� "� ,�7 � ,s#C� ,�.I����
/#� �S7���. ]H[.-��� ��� s#C�� �" h�& �o�& ����#� "� ��� � �� +���� � ��4��#�'+#� �� ,�-��� � �7� ���n#4 �,��h�& �7���& ��"�= 7�7� �" +���.� ����� "��4 .
��#� �� ,��h�& �"� ����� "��4Calabria +���� � ��4" h�& %& ��� s#C� �?o %& ���#� ��� �7� ���� 0&" ��"s= ,�.]ZZ[.
������ � %& �7� +#� �� D��& � ����� D��& ,�-��� �#*���� >- ,�.7E�� � X!� �����'7���. +���.� ]H[.�7� %���1 "��4 � %X!� "� �-��� ��� �#*�,�"
� �7� +#� �� ��" ,�-��� ��#� � �9�E 7��#�'�"�n X!� "� j�� ,�'+� "� +���.� 7���& �� ��9 � .7&7� j�� �?o %& %9 _�� � ��+%��#� ,�� ���#� � ���@o� '���n#4
%��#� ��# ������ ~7o �?o %& � �7� ��� � �� +���� � ��4" h�& �o�&)�4 u� "� g;�q��"� 4 �� � ����.#9 (��� ��#�� h�& "��4]HH �HF[.y���'��#� �� ,��h�& �"��4�� %X!� ��� "� ������.%��#� �4�6� �Xa�� "� ,�� i�7� j�� +��# s#C� �o�& �
%��#� %X!� D��&� ��� � D��& ,�-��� `"#Q %& %9 ��� �7� ,�� �7��#�7�.�?o7� j��+%��#� ��� ��#& %X!� & ���9 ,�.� �� �uw� ,� .� q�9 5�o �7 � 7��#�
%��#� ��7= & ��� 7��&�6� %��#� � ,���� >- 5�#o � .s#C� ��7�� �-* %& %*#� �&
����������������������������������������������������������� 1- Crustal thinning or shortening.
7�r �+sr ��t�� HHP
� �,"#�� "� 5n�7E �D��&� ��� � D��& ,�-��� AB� �" ���9 ,�.� �� �uw� �-* +�#�� 9 .%&�?o ���y&�* ,�.����2��X!� "� , �2w� 'q�9 �-* c�n� ��� � �+���.�
� �6�� ����� �6@5�� +�#�!� "� �#*# �"�& ,�.�����4� � %X � �� � , � ,�.]H[O�@� ��� X� �-* %9 �" :7�"�� �&#�*��#@� � 7�7� ,�.N�4 � $� "� q�9 .��� ��
�n � q�9 �-* `"#Q ��� "� 7��& ��"� � 4:��� ��#& �& ) .
�$���W � �2�� �B& � �,#� � q.��� �}�� �7}� ��� ���@E �� �� ������� . }�9� �Giles Droop �
,�}n= � � �7��}� `� }$� %}L�"� �}?o %}& ��}�� ����}���Dave Plant �} r�����}�� O%�#@� %��y� "� %9 +���?��� ���� ������� (� �� 6�D@9 �. "���&,�� 9 �} 6�� 7��-
#��.
X���� ]Z[/ �9��.�~ +sr .�"��C��� �& +���.� ( ) (#�* ���?��� ,�-��� , ��"�&# �#L< � �
;9#�<;� � ��#6�# ����#�& ���"�� ,�-���9 ��& �6�����# � O�� �"�q��@. ��@�C. +� �� ����� �� �@y�� �+�-CQ� ��������"#� -� �� )SU\R(.
]H[/ �9��.�" ��!'� �?6� �� %�E�� ��#� �� +���.� ( ) (#�* ,�"������"�9 %���" �7�"���������� �� )ZFPH.(
]F[~ +s#./ �9�� �.~ 7�# �.�"D@9 %& +���.� ( ) (#�* ���?��� ,�-��� , �# � ��"�� ���9 3�–���#�& "����9 � �����"#?& �@y�� ���@.� � ��@�� +� �� ������
�� +����� ������ +���M#?& ��� ,�)ZFPZ(.[4] Holland T.J.B., Powell R., "An internally consistent thermodynamic dataset with uncertainties and correlation. 2: Data and results", Journal of metamorphic Geology 3 (1985) 343-370.
]G[�9�� /.�+sr ~.�7�r ~.�,7-�y ~.�/ , �o .�""#?�� � �?6� �� m���"� ��" &� �+���.� ( ) (#�* ��#� �� %X!� "� �-���9+�y� +���"��� q��@. ��@�� �����
+� �� .+� 9 �.�& 7�-� ��������� "#� -� �)ZFPZ.([6] Kretz R., "Symbols for rock forming minerals. American Mineralogist",68 (1983) 277-279.[7] Yardley B.W.D., "An introduction to metamorphic petrology", Longman,
Harlow (1989) p. 319.
"� �7� +#� �� ��" ,�-��� , ��"�&# �#L< ... HH{
[8] Bucher K., Frey M., "Petrogenesis of metamorphic rocks", Springer Verlag (1994) p. 318. [9] Spear F.S., "Metamorphic phase equilibria and pressure-temperature time paths", Mineralogical Society of America. Monograph. (1993) p. 799. [10] Rios C., Garcia C., Takaus A. "Tectono-metamorphic evolution of the Silgara Formation metamorphic rocks in the southern Santander Massif, Colombian Andes", Journal of south American Earth sciences 16(2) (2003) 133-154. [11] Graeβner T., Schenk V., "Low-pressure metamorphism of Palaeozoic pelites in the Aspromonte, southern Calabria: constraints for the thermal evolution in the Calabrian crustal cross-section during the Hercynian orogeny", Journal of Metamorphic Geology 17 (1999) 157-172. [12] Holland T.J.B., Powell R., "An internally consistent thermodynamic data set for phases of petrological intrest", Journal of Metamorphic. Geology 16 (1998) 309-343. [13] Patino-Douce A.E., Johnston A.D., Rice J.M., "Octahedral excess mixing properties in biotite: a working model with application to geobarometry and geothermometry", American Mineralogist 78 (1993) 113-131.[14] Blümel P., Schreyer W., "Progressive regional low pressure metamorphism in Moldanubian metapelites of the Northern Bavarian Forest, Germany", Krystalinikum 12 (1976) 7-30. [15] Wagener-Lohse C., Blümel P., "Prograde metamorphose vom Niederdruck-Typ in der Grenzzone Saxothuringikum/Moldanubikum E’Tirschenereuth/NE-Bayern", Beiheft zu Fortschritte der Mineralogie 62 (1984) 254-255. [16] Miyashiro A., "Metamorphism and Metamorphic Belts", George Allen and Unwin Ltd., London (1973). [17] Hudson N.F.C., "Regional metamorphism of some Dalradian pelites in the Buchan area, N.E. Scotland", Contributions to Mineralogy and Petrology 73 (1980) 39-51.
]ZP[~ "7& ,7��@* .�"��" & %X!� ��"s= � ��#� �� ,�-��� �4� �� �� � ,<#�� �� (�6� � <� ��.�� ��&� �?Q� �;& � %���� ,����""�7�"� �����"�9 %���" ��� �� �������
)ZFPZ(%1CQ ZF{ .[19] Weber K., "Variscan events: early Paleozoic continental rift metamorphism and late Palaeozoic-crustal shortening. In: DHW Hutton and
7�r �+sr ��t�� HFI
DJ Sanderson (eds) Variscan Tectonics of the North Atlantic Regional (Geol. Soc. London. Spes. Publ. no.14)", Blackwell Scientific, Oxford (1984) pp. 3-22.[20] Barton M.D., Hanson R.B., "Magmatism and the development of low-pressure metamorphism: Implications from thermal modelling at the western United States", Geol. Soc. Amer. Bull. 101 (1989) 1051- 1065. [21] De Yoreo J.J., Lux D.R., Guidotti C.V., "Thermal modelling in low-pressure/high-temperature metamorphic belts", Tectonophysics 188 (1991) 209-238. [22] Moazzen M., Droop G.T.R., Saki A., "Low pressure regional metamorphism in the Mahneshan area, Western Iran", Geophysical Research Abstracts 5 (2003) 1254.
]HF[/ �9��. �r~ +s. �r~ 7�.�"�, ��"�&# � � ��#� �� 3�� ,�-���9 �@�� O� �%�E�� ��#� �� ��" ,�-��� +���.� %X!� ,�"���� ~#?o ���@.� � ��@6� � ���&
+��� �� �@-& �+� -� ����� ��)ZFPZ(.