Quantifying the influence of sill intrusion on the thermal evolution of organic‐rich sedimentary rocks in nonvolcanic passive margins: an example from ODP 210‐1276, offshore Newfoundland, Canada

• Published in: Basin Research
• Main Authors: Peace, Alexander, McCaffrey, Ken, Imber, Jonathan, Hobbs, Richard, van Hunen, Jeroen, Gerdes, Keith
• Other Authors: Royal Dutch Shell
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Canada; Newfoundland
• Online Access: http://dx.doi.org/10.1111/bre.12131; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbre.12131; https://onlinelibrary.wiley.com/doi/pdf/10.1111/bre.12131

Abstract Intrusive magmatism is an integral and understudied component in both volcanic and nonvolcanic passive margins. Here, we investigate the thermal effects of widespread ( ca . 20 000 km 2 ) intrusive magmatism on the thermal evolution of organic‐rich sedimentary rocks on the nonvolcanic Newfoundland passive margin. ODP 210‐1276 (45.41°N, 44.79°W) intersects two sills: an older, upper sill and a younger, lower sill that are believed to correspond to the high amplitude ‘U‐reflector’ observed across the Newfoundland Basin. A compilation of previous work collectively provides; (1) emplacement depth constraints, (2) vitrinite reflectance data and (3) 40 Ar/ 39 Ar dates. Collectively, these data sets provide a unique opportunity to model the conductive cooling of the sills and how they affect thermal maturity of the sedimentary sequence. A finite differences method was used to model the cooling of the sills, with the model outputs then being entered into the EASY %R o vitrinite reflectance model. The modelled maturation profile for ODP 210‐1276 shows a significant but localized effect on sediment maturity as a result of the intrusions. Our results suggest that even on nonvolcanic margins, intrusive magmatism can significantly influence the thermal evolution in the vicinity of igneous intrusions. In addition, the presence of widespread sills on nonvolcanic passive margins such as offshore Newfoundland may be indicative of regional‐scale thermal perturbations that should be considered in source rock maturation studies.