Timing of Acadian deformation in northeastern Maine
Journal Article
·
· Geology; (United States)
/sup 40/Ar//sup 39/Ar ages determined for 24 mineral separates from the Pleasant Lake, Hunt Ridge, and Cochrane Lake plutons bear on the timing of the main phase of the Acadian orogeny in northern Maine. Six hornblende samples and one clinopyroxene sample have only minor disturbances in their release spectra. The increments with concordant ages form overlapping plateaus at 403 +/- 4 Ma. Many of the biotite samples have discordant release spectra. The average of their total gas ages is 400 +/- 6 Ma. Calculated closure temperatures for the hornblendes and biotites are 550/sup 0/C and approximately 350/sup 0/C, respectively. The difference between closure temperatures and concordancy in ages demonstrates that the plutons cooled very rapidly upon emplacement. Therefore, the /sup 40/Ar//sup 39/Ar ages date both the time of argon retention in the minerals and the time of emplacement of the plutons. The best estimate for their time of emplacement is the average of the combined ages of the micas, hornblendes, and clinopyroxene, 402 +/- 6 Ma. The plutons are undeformed and crosscut upright, open, Acadian folds in the Carys Mills, Smyrna Mills, and Madrid(.) Formations. The age of the Pleasant Lake, Hunt Ridge, and Cochrane Lake plutons therefore places a lower limit of 402 +/- 6 Ma on the time of Acadian folding in northern Maine.
- Research Organization:
- Univ. of Maine, Orono (USA)
- OSTI ID:
- 5340399
- Journal Information:
- Geology; (United States), Journal Name: Geology; (United States) Vol. 15:1; ISSN GLGYB
- Country of Publication:
- United States
- Language:
- English
Similar Records
Rb-Sr whole-rock and /sup 40/Ar//sup 39/Ar mineral ages of the Hartland stock, south-central Maine: a post-Acadian representative of the New Hampshire Plutonic series
The eastern limit of Acadian high grade metamorphism in northern New England: Implications for the location of the Acadian Suture''
Preliminary fission track ages for samples from western Maine: Implications for the low temperature thermal history of the region
Journal Article
·
Thu Dec 31 23:00:00 EST 1981
· Am. J. Sci.; (United States)
·
OSTI ID:5130406
The eastern limit of Acadian high grade metamorphism in northern New England: Implications for the location of the Acadian Suture''
Conference
·
Sun Feb 28 23:00:00 EST 1993
· Geological Society of America, Abstracts with Programs; (United States)
·
OSTI ID:5579280
Preliminary fission track ages for samples from western Maine: Implications for the low temperature thermal history of the region
Conference
·
Tue Dec 31 23:00:00 EST 1991
· Geological Society of America, Abstracts with Programs; (United States)
·
OSTI ID:5589337
Related Subjects
58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
AGE ESTIMATION
AMPHIBOLE
ARGON 39
ARGON 40
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOTITE
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FEDERAL REGION I
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
HORNBLENDE
IGNEOUS ROCKS
ISOTOPE DATING
ISOTOPES
LIGHT NUCLEI
MAINE
MICA
MINERALS
NORTH AMERICA
NUCLEI
PLUTONIC ROCKS
RADIOISOTOPES
ROCKS
SILICATE MINERALS
STABLE ISOTOPES
USA
YEARS LIVING RADIOISOTOPES
580100* -- Geology & Hydrology-- (-1989)
AGE ESTIMATION
AMPHIBOLE
ARGON 39
ARGON 40
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOTITE
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FEDERAL REGION I
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
HORNBLENDE
IGNEOUS ROCKS
ISOTOPE DATING
ISOTOPES
LIGHT NUCLEI
MAINE
MICA
MINERALS
NORTH AMERICA
NUCLEI
PLUTONIC ROCKS
RADIOISOTOPES
ROCKS
SILICATE MINERALS
STABLE ISOTOPES
USA
YEARS LIVING RADIOISOTOPES