Final answer:
The Newark rifts formed due to the extension of the Pangean crust, associated with massive volcanic eruptions, leading to the breakup of Pangaea and the opening of the Atlantic Ocean at the end of the Triassic period.
Step-by-step explanation:
The Newark rifts were formed near the end of the Triassic period primarily by the extension of the Pangean crust. This geological event was part of the continental rifting process that led to the breakup of the supercontinent Pangaea. The eventual opening of the Atlantic Ocean was a result of this extensive period of rifting. Evidence shows that the breakup of Pangaea began around 200 million years ago, and this tectonic activity corresponded with massive volcanic eruptions and considerable climate changes, characterized by a significant increase in atmospheric CO₂ levels and a global temperature rise.
During the Triassic-Jurassic transition, there was also a major extinction event, which some geoscientists associate with the increased CO₂ from volcanic eruptions of a large igneous province in the Atlantic region. While there were hypotheses about an asteroid impact, there is no evidence to support this as the cause of the rift formations or the extinction event at the end of the Triassic. Instead, the massive volcanism associated with the opening of the Atlantic Ocean is considered to be a significant contributing factor.