TOPIC 2 ( PROTOLITH )

• Pelites

  Al-rich rocks with SIO2, Al2O3, and K2O 

  Minerals are transformed into aluminosilicates. 

  Non-uniform stress produces foliated rocks

  Uniform stress produces Hornfels
• PELITES

  metamorphic rocks derived from pelitic protolith

  
• Quartzofeldspathic rocks

  Psammitic rocks

  Protoliths with high concentration of SiO2, Na2O and K2O, and low FeO and MgO

  Rocks rich in quartz and feldspars

  Al2O3 is more variable depending if the protolith is grayawcke or micaceous granite
• Quartzofeldspathic rock- protolith of psammitic

  
• Calcareous rocks

  Protolith rich in CaO, MgO, CO2 and FeO found in carbonate sedimentary rocks, as well as SiO2 and Al2O3 for chert, siliciclastic sand/mud

  Results to marble and skarn deposits
• calcerous rocks- carbonate protolith

  
• Intermediate-Basic Igneous rocks -Protoliths enriched in MgO, FeO, and CaO and relatively depleted in SiO2, Na2O, and K2O

  Basalt, andesite, diorite, gabbro

  Commonly with amphibole, pyroxene, calcic plagioclase, mafic phyllosilicate, and Fe oxides
• intermediate-basic igneous rock - intermediate- basic protolith

  
• Ultrabasic Igneous rocks -Protoliths enriched in MgO, FeO, CaO, Ni, Cr, and strongly depleted in SiO2, Na2O, and K2O

  Protoliths include pyroxenite and peridotite
• ultrabasic igneous rocks - ultrabasic protolith