2002
DOI: 10.1029/2000tc001270
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Mechanisms and timing of exhumation of collision‐related metamorphic rocks, southern Brooks Range, Alaska: Insights from 40Ar/39Ar thermochronology

Abstract: [1] New 40 Ar/ 39 Ar thermochronologic data document the spatial distribution of cooling ages and rates across a metamorphic culmination in the south central Brooks Range, providing important constraints on the timing and processes responsible for exhumation of deep-seated metamorphic rocks. The data indicate widespread episodic exhumation-related cooling, with short-lived events in the mid-Albian to early Cenomanian and Paleocene to Eocene. Hornblende ages indicate that cooling from the metamorphic peak bega… Show more

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Cited by 16 publications
(22 citation statements)
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References 41 publications
(96 reference statements)
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“…Precipitation estimates for the PCF ranged between 500 to 1500mm/yr (Spicer & Parrish 1990). Globally, there is evidence for two warming events in the Maastrichtian (Li & Keller 1998;Barrera & Savin 1999;Nordt et al 2003;Wilf et al 2003) that may overlap with the timing of the PCF deposition. The older of these two warming events occurred between 69.5 and 68.5 Ma and is associated with increases in atmospheric pCO 2 concentrations of 1000-1200 ppmv (Nordt et al 2003).…”
Section: Palaeoclimatic Palaeoenvironmental Setting and Faunamentioning
confidence: 99%
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“…Precipitation estimates for the PCF ranged between 500 to 1500mm/yr (Spicer & Parrish 1990). Globally, there is evidence for two warming events in the Maastrichtian (Li & Keller 1998;Barrera & Savin 1999;Nordt et al 2003;Wilf et al 2003) that may overlap with the timing of the PCF deposition. The older of these two warming events occurred between 69.5 and 68.5 Ma and is associated with increases in atmospheric pCO 2 concentrations of 1000-1200 ppmv (Nordt et al 2003).…”
Section: Palaeoclimatic Palaeoenvironmental Setting and Faunamentioning
confidence: 99%
“…The palaeo-latitude of Cretaceous rocks in this area is thought to be between 828 and 858N (Witte et al 1987;Besse & Courtillot 1991;Rich et al 2002;. Ash layers in the vicinity of the Liscomb Bonebed returned weighted mean K - Ar and 40 Ar/ 39 Ar ages of 69.1 + 0.3 Ma (Conrad et al 1990) and 69.2 + 0.5 Ma (Flaig 2010), which is consistent with an Early Maastrichtian age (Maastrichtian ¼ 70.6-65.5 Ma, ICS 2010 Geologic Time Scale) suggested by palynological data (Frederiksen 1990;Fiorillo et al 2010a, b;Flaig et al 2013).…”
Section: Geological and Tectonic Settingmentioning
confidence: 99%
“…Just north of the Schist Belt lies the Central Belt, which contains rocks of similar age and affinity but which are less penetratively deformed and which appear to have experienced lower pressures during metamorphism (Till et al, ; Figure ). The boundary between the Schist and Central Belt is poorly defined in most places and has been interpreted as a zone of top‐to‐the‐north thrust faulting (e.g., Moore et al, ; Patrick et al, ; Till, ; Till et al, ; Till & Snee, ), a zone of top‐to‐the‐south back thrusting (e.g., Vogl et al, ), or as a strain gradient north of which the younger extensional foliation is no longer dominant (Christiansen & Snee, ; Law et al, ; Little et al, ). To its south, the Schist Belt is structurally overlain by less resistant, lower grade rocks of the Greywacke‐Phyllite belt , which are in turn structurally overlain by normal fault‐bound fragments of the Devonian‐Jurassic Angayucham oceanic terrane and/or Cretaceous Yukon‐Koyukuk Basin sediments (e.g., Box, ; Carlson, ; Gottschalk & Oldow, ; Miller & Hudson, ; Moore et al, , ; Oldow et al, ; Patton Jr. et al, , ; Figure ).…”
Section: Geological Settingmentioning
confidence: 99%
“…These yield mostly Cretaceous ages (~140–100 Ma) but are often characterized by complex 40 Ar/ 39 Ar step‐heating spectra. Such complexity may reflect variable thermally induced diffusive argon loss, a mixture of mica ages or phases, and/or inclusion of excess 40 Ar, thereby rendering geological interpretations uncertain and leading to a wide diversity of tectonic models (Blythe et al, , ; Box, ; Brosge & Reiser, ; Christiansen & Snee, ; Dillon et al, ; Dinklage, ; Gottschalk, ; Gottschalk & Oldow, ; Gottschalk & Snee, ; Little et al, ; Nelson & Grybeck, ; Patton Jr. et al, ; Silberman et al, ; Till, , ; Till et al, ; Till & Snee, ; Toro et al, , ; Turner et al, ; Vogl, ; Vogl et al, ). The difficulty interpreting 40 Ar/ 39 Ar white mica ages with respect to the age of fabric development has added to the disagreement about the metamorphic and structural evolution of the Brooks Range and thus to the relative overlap of structural events occurring in the hinterland compared to those documented at higher structural levels.…”
Section: Geological Settingmentioning
confidence: 99%
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