Mesozoic erosion rates in northern New England

Research Article| January 01, 1980 Mesozoic erosion rates in northern New England JOHN T. DOHERTY; JOHN T. DOHERTY 1Weston Geophysical Corporation, Westboro, Massachusetts 01581 Search for other works by this author on: GSW Google Scholar JOHN B. LYONS JOHN B. LYONS 2Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire 03755 Search for other works by this author on: GSW Google Scholar Author and Article Information JOHN T. DOHERTY 1Weston Geophysical Corporation, Westboro, Massachusetts 01581 JOHN B. LYONS 2Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire 03755 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1980) 91 (1): 16–20. https://doi.org/10.1130/0016-7606(1980)91<16:MERINN>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation JOHN T. DOHERTY, JOHN B. LYONS; Mesozoic erosion rates in northern New England. GSA Bulletin 1980;; 91 (1): 16–20. doi: https://doi.org/10.1130/0016-7606(1980)91<16:MERINN>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Ten stocks of the White Mountain Plutonic-Volcanic Series in New Hampshire have been sampled, and have yielded material for nine apatite and six zircon fission-track dates. The zircon ages (λ = 6.85 × 10−17 y−1) are slightly younger than isotopic ages (chiefly K-Ar) which have been previously determined on these same intrusives, but the apatite ages are considerably younger, averaging about 55% of isotopic age for intrusives older than 130 m.y., and 85% of isotopic age for intrusives younger than 130 m.y.The differences between zircon and apatite ages have been used in conjunction with heat-conduction theory to show that 180 m.y. ago ambient wallrock temperatures of White Mountain intrusives (at the present erosion level) were ∼ 170 to 200°C. For intrusives 115 m.y. old, ambient wallrock temperatures were about 100°C. These numbers, assuming a 25 to 30 °C/km geothermal gradient, translate to depths of emplacement of ∼ 3 to 3.6 km (115 m.y.) and ∼ 5.3 to 7.6 km (180 m.y.), and indicate an average erosion rate, since Jurassic time, of 1 km per 32 m.y. (0.031 mm/yr). Jurassic isobaric surfaces are now tilted northeastward at an approximate gradient of 0.012 to 0.015 km per kilometre, Cretaceous isobaric surfaces at 0.007 to 0.008 km per kilometre and Devonian isobaric surfaces at an approximate gradient of 0.039 km per kilometre. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.