MESOZOIC HOTSPOTS AND IGNEOUS EVENTS: CONTRASTS AND CONTENTIONS

Jelle de Boer had wide interests, but especially, his work on Mesozoic igneous events and structural features in New England greatly overlapped my own research. Although we both studied patterns of magmatic rocks and the tectonics associated with them, our understanding of their origins had fundamental differences.

A “hotspot” is a place of anomalous volcanism not associated with a plate boundary mechanism. A common belief is that such volcanism is caused by a narrow mantle plume rising from the mantle-core boundary. Jelle and I became interested in this model in the early 1970s, after Peter Coney and Jason Morgan made specific proposals for a deep mantle plume to produce Mesozoic igneous events in New England, connecting them to the chain of volcanic seamounts extending offshore.

Starting with his visit to the University of North Carolina in 1976, where I was a PhD student, our thoughts about this mechanism continued to diverge, even when we were co-authors. We also had differences about the spectacular basalt flows of the Triassic-Jurassic basins, and how they were related to the large dikes of the region. Plus a few other contentions! Even so, Jelle and I had mutual respect, and I was fortunate to be his friend. From my biased viewpoint, our different ideas about Mesozoic geology in New England are discussed, some of which are settled but still important!