Bedrock Geology of Ontario, Dike Swarm - 1: 250 000

Coordinate system: 4269 - "NAD83"


This data set can be used to identify dikes, which are tabular bodies of igneous rock which have intruded pre-existing geological units near the Earth's surface. Dikes are therefore long linear bodies of igneous rock that can extend laterally for hundreds of kilometers with a width of perhaps a few hundred meters. Dikes normally occur, not as single dikes, but rather as several parallel dikes forming a dike swarm all of the same material which intruded at roughly the same time. The most common dike swarms in the Precambrian of Ontario are diabase dike swarms extending up to 3000 km in length which can form up to 30% of the Earth's crust at the center of the swarm.

This data set is part of the Bedrock Geology Data Set, which is a Geological map of the Province and shows the distribution of bedrock units underlying Ontario. It illustrates geological rock types, major faults, iron formations, kimberlite intrusions, and dike swarms. The geology of the Province consists of Precambrian rocks of the Canadian Shield and Phanerozoic sedimentary rocks in basins that overlie the Canadian Shield. Based on differences in age, metamorphism and tectonic setting, the Precambrian rocks are subdivided into the Superior, Southern and Grenville provinces. The Phanerozoic rocks occur in four basins. Major faults and shear zones are also included. The legend is subdivided geochronologically in the Phanerozoic, but geochronometrically in the Proterozoic and Archean. The Archean rocks of the Superior Province are subdivided into lithologic units. Supracrustal units of the Southern Province and the Phanerozoic Eon are subdivided lithostratigraphically. The Grenville Province is subdivided into major tectonic blocks and within each block the legend is mainly lithologic, with only part of the supracrustal rock record subdivided into lithostratigraphic units. The dataset is an overview of this geology on a Provincial Compilation scale of 1:250 000 and it illustrates geological rock types, major faults, iron formations, kimberlite and dike swarms.

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