Page 9 - Volcanic Textures A Guide To The Interpretation of Textures In Volcanic Rocks

Characteristics ........................................................................................................................................ 118
Dimensions of pyroclastic surge deposits ............................................................................................. 119
Significance ............................................................................................................................................ 119
Suspension transport and volcaniclastic suspension deposits ..................................................................................... 120
Pyroclastic fall deposits ................................................................................................................................. 120
Characteristics ........................................................................................................................................ 120
Water-settled pyroclastic fall deposits ........................................................................................................... 121
Suspension sedimentation associated with subaqueous volcaniclastic mass flows ....................................... 121
Sedimentation in volcanic terranes ............... ............................................................................................... 122

Part 5. Alteration: an integral part of textural evolution

Alteration events in the Mount Read Volcanics ........................................................................................... 165
Alteration of lavas, shallow intrusions and related autoclastic breccias ...................................................................... 166
Original texture ............................................................................................................................................. 166
Glassy margins .............................................................................................................................................. 166
Mixed glassy and spherulitically devitrified zones ....................................................................................... 167
Spherulitic or microlitic cores of lavas and shallow intrusions .................................................................... 167
General trends and implications .................................................................................................................. 168
Alteration of pumiceous deposits ................................................................................................................................ 168
Originally glassy and permeable deposits ..................................................................................................... 168
Phyllosilicate alteration ................................................................................................................................. 168
Two-phase feldspar and phyllosilicate alteration ......................................................................................... 168
General trends and implications .................................................................................................................. 169

References ............................................................................................................................. 181
Index ………………………………………………………………………………….....191