The Long Range dikes are a

Neoproterozoic The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic geologic eon, eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era an ...

mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...

dike swarm of

Newfoundland and Labrador Newfoundland and Labrador is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region of Labrador, having a total size of . As of 2025 the populatio ...

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

. It consists of a

large igneous province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive ( sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The format ...

with an area of that was constructed about 620 million years ago when

Laurentia Laurentia or the North American craton is a large continental craton that forms the Geology of North America, ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of ...

broke-up from

Baltica Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains. The thick core of Baltica, the East European Craton, i ...

. Its formation might have occurred when the ancient Iapetus Ocean began to open. Long Range is the oldest of a series of

magmatic Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...

events that occurred along the eastern margin of Laurentia 620–560 Ma, before the opening of the Iapetus Ocean. It can be linked to magmatism in

, the basaltic dike swarm in

Egersund Egersund is a List of towns and cities in Norway, town in Eigersund municipality in Rogaland county, Norway. The town is located along the southwestern coast of Norway, about south of the city of Stavanger (city), Stavanger. The town is situat ...

, Norway, and Baltoscandian swarms. It was followed by the 590 Ma Grenville-Adirondack swarm,

Upstate New York Upstate New York is a geographic region of New York (state), New York that lies north and northwest of the New York metropolitan area, New York City metropolitan area of downstate New York. Upstate includes the middle and upper Hudson Valley, ...

, associated with separation from Amazonia and the 563 Ma Sept Îles, Quebec, layered intrusions (coeval with the Catoctin large igneous province) associated with the break-up of the Dashwoods microcontinent of West Newfoundland.

References

; Notes ; Sources * * Dike swarms Neoproterozoic magmatism Igneous petrology of Newfoundland and Labrador {{Canada-geology-stub