Geological Survey of Finland Bulletin 289 - arkisto.gsf.fi

CONTENTS
Introduction .................................................... 5
General description of the diabase dykes . ... . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Width and length oE the diabase dykes .......... . ................. 6
The strike and dip oE the diabase dykes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Contact conditions ...... ... .... ..... .... . . .. .................. 10
Multiple intrusions ..... . .. ..... .... .. . . ... ................. . .. 12
Intrusion mechanism .......................................... 13
Shearing along the diabase dykes . ........... .... ......... ... . . . . 17
Description oE types oE rock . ........ ..... . ...... .... .. .... . ...... 19
Mineralogy .... . ... ... ... . .... . ....... .. ......... . ........... 19
Quartz/ calcite-Eilled amygdales ....... . ............ ... . . ....... .. 23
Areal variations in mineral composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Chemical composition oE the diabase dykes .... . . . .... ................. 24
Discussion ... . ... ... .. . ........ .. ........ .... .. .. ..... .. . . .... . . 25
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 29
ReEerences ...... . . ..... . .. ........... .. .. .. ................ .. ... 30