U-Pb Dating of Calcite Veins in the Champlain Valley: Constraints on Post- Paleozoic Rejuvenation in the Eastern North American Margin

The last documented tectonic event believed to impact the New England region was the opening of the Atlantic Ocean 200 Myr ago. Geologists have long been puzzled by the mountainous topography of the region. Recent research... [ view full abstract ]

The last documented tectonic event believed to impact the New England region was the opening of the Atlantic Ocean 200 Myr ago. Geologists have long been puzzled by the mountainous topography of the region. Recent research now suggests that tectonic activity may have occurred as recently as 15 Myr ago, resulting in regional uplift. Evidence of passive margin rejuvenation in the Southern Atlantic Margin, sediment flux in the Baltimore Canyon Trough, and fission track dating in the Eastern North American Margin (ENAM), suggest that the ENAM has experienced post-Paleozoic rejuvenation. Further evidence of this rejuvenation would be documented in brittle fractures in the surficial bedrock of New England. To get estimated dates on the timing of the fracturing events calcite samples have been dated using U-Pb LA-ICPMS geochronology. Calcite is a common fault hosted mineral found in the Champlain Valley. Calcite samples were collected from brittle fractures in the area to conduct this research. The ages of the calcite veins have provided estimates for the timing of fracturing events, which when compared to other evidence of passive margin rejuvenation further support the hypothesis that this occurred in the ENAM. This paper provides new evidence that there has been significant tectonic activity in the Champlain Valley and the ENAM, an area long thought to be tectonically inactive.