Late-orogenic backfolding and extension in the Brooks Range collisional orogen, northern Alaska

Vogl, James J.

doi:10.1016/s0191-8141(01)00155-9

Cited by 16 publications

(22 citation statements)

References 58 publications

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“…D 1 involved north directed deformation that produced a pervasive foliation that is generally parallel to the lithologic layering along the transect. This event, which includes formation of most of the north directed fold‐thrust belt, probably spanned most of the Cretaceous and may have ended in the Aptian Vogl [2002]. The post‐D 1 structural history of the Brooks Range has been more highly debated.…”

Section: Structure and Metamorphism Of The Study Areamentioning

confidence: 99%

“…The post‐D 1 structural history of the Brooks Range has been more highly debated. Recent structural mapping by Vogl [2002] has shed light on this history and is summarized as follows. Porphyroblasts overgrow the D 1 foliation in the deepest levels of the NGS zone (kyanite, chloritoid, or albite) and in the NEA zone (garnet, biotite, or chloritoid), indicating post‐D 1 heating.…”

Section: Structure and Metamorphism Of The Study Areamentioning

confidence: 99%

“…He described south side down extensional shear bands, as well as shallowly south dipping S 2 crenulation cleavages, which are locally axial‐planar to north‐vergent folds. Vogl [2002] suggested that the vergence reversal between the north and south flanks of the culmination delineate the regional‐scale south closing backfold (Figure 3a).…”

Section: Structure and Metamorphism Of The Study Areamentioning

confidence: 99%

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

2002

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[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 began at 105 -103 Ma across the epidoteamphibolite facies core of the culmination. Mica ages, however, increase southward from $90 Ma to $100 Ma, indicating that average cooling rates increased southward. Thermal modeling suggests that Albian cooling is the result of a short-lived exhumation event that ended by the early Cenomanian, and that exhumation rates were between $1 and 8 mm/yr, with higher rates toward the south. The southward increase in cooling/exhumation rates is attributed to a southward increase in the component of tectonic exhumation by normal faulting on the south flank of the range. Rapid erosion, which is recorded by thick molasse deposits in flanking basins that are coeval with rapid cooling, may have been aided by surface uplift in the footwall of these faults. The northward younging of mica ages may not be explained by a simple core complex model involving metamorphic rocks being progressively dragged out from beneath an extensional fault. The overall spatial distribution of metamorphic zones and cooling ages/rates is best explained by a two-step process: (1) a brief episode of extensional faulting producing a regional northward tilt with superimposed doming during the AlbianCenomanian and (2) relative uplift of the core during renewed Tertiary contraction, which enhanced the domal geometry. Diffusion-domain modeling of K-feldspar data indicates a period of little or no cooling that spanned much of the Late Cretaceous followed by rapid increase in cooling rates in the Paleocene to Eocene. Increased Tertiary cooling rates are attributed to renewed contraction leading to surface uplift and erosion.

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Section: Structure and Metamorphism Of The Study Areamentioning

confidence: 99%

Section: Structure and Metamorphism Of The Study Areamentioning

confidence: 99%

Section: Structure and Metamorphism Of The Study Areamentioning

confidence: 99%

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

2002

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“…Till and others (2008a) report that gneissic textures are particularly common where the unit is closest to metaplutonic rocks of the Arrigetch Peaks and Mount Igikpak orthogneiss (unit Dogn). Mafic rocks within the unit contain assemblages of the albite-epidote-amphibolite facies (Dusel- Bacon and others, 1989;Vogl, 2002); exposures west of the major orthogneiss bodies appear to be lower in grade (Nelson and Grybeck, 1980;Toro, 1998). Unit may, in part, represent a higher metamorphic grade equivalent of a number of units of the Brooks Range, including S_bs, Dbf, Degh, D_cs, and |<aqm.…”

Section: Devonian To Proterozoicmentioning

confidence: 99%

Geologic map of Alaska

Wilson¹

2015

Scientific Investigations Map

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“…Mull, oral commun., 2007). Large-magnitude Early to mid-Cretaceous extension of the overthickened orogen along shallow dipping, top-to-south normal faults has been documented in the southern Brooks Range (for example, Miller and Hudson, 1991;Blythe and others, 1996;Vogl, 2002;Vogl and others, 2002), but younger, top-to-north extensional collapse that could account for normal displacement of the Gilead succession on the north edge of the range has never been recognized. Alternatively, the missing Lower Cretaceous units could be absent due to local non-deposition or may have been removed by erosion (Schenk and Bird, 1993) or mass wasting before deposition of the Gilead sandstone.…”

Section: Structure Of the Gilead Syncline And Gilead Creek Traversesmentioning

confidence: 99%

Stratigraphic and structural investigations in the Ivishak River and Gilead Creek areas: Progress during 2007

Decker¹,

Wartes²,

Wallace³

et al.

Preliminary Results of Recent Geologic Field Investigations in the Brooks Range Foothills and North Slope, Alaska

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Contractional deformation of foreland basin deposits adjacent to the northeast-southwest-trending mountain front in the east-central Brooks Range foothills exposes rock units of Albian to Late Cretaceous age that are largely concealed in the subsurface to the west and removed by erosion to the east. The informally named Gilead sandstone and overlying units in this area provide valuable insights into depositional systems active during the early and middle phases of foreland basin evolution, as well as an opportunity to study their responses to subsequent Brookian deformation. Systematic traverses of the Ivishak River, Gilead syncline, and Gilead Creek yield ubiquitous evidence of sediment gravity flow depositional processes in both the highly amalgamated sandstones and the intervening, finer-grained and thinner-bedded intervals throughout the Gilead sandstone, Seabee-equivalent strata, and the overlying Canning Formation. The amalgamated sandstone facies association of the Gilead succession contains many characteristics of hyperpycnal flow deposits, and submarine channels are locally preserved. Much of the unit may represent east-or northeast-flowing axial foredeep channel belt deposits. Sediment gravity flow sandstones in the upper parts of the Gilead unit that contain possible wave-influenced sedimentary structures may have been deposited south of the foredeep in shallower orogenic wedge-top, upper slope, or ramp settings. The Gilead sandstone has previously been interpreted to belong to a far-traveled allochthon, but we have found no compelling structural evidence to support this interpretation. Instead, observations appear consistent with lower Brookian strata at Gilead syncline forming the passive roof of a triangle zone duplex containing structurally thickened Valanginian and older strata. The Gilead sandstone itself is more strongly deformed on strike to the west at the Ivishak River. Transverse tear and rotational faults may account for the alongstrike compartmentalization of deformation. These preliminary interpretations require further scrutiny and the incorporation of pending analytical results from samples collected during these investigations.

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Late-orogenic backfolding and extension in the Brooks Range collisional orogen, northern Alaska

Cited by 16 publications

References 58 publications

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

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

Geologic map of Alaska

Stratigraphic and structural investigations in the Ivishak River and Gilead Creek areas: Progress during 2007

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Late-orogenic backfolding and extension in the Brooks Range collisional orogen, northern Alaska

Cited by 16 publications

References 58 publications

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

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

Geologic map of Alaska

Stratigraphic and structural investigations in the Ivishak River and Gilead Creek areas: Progress during 2007

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Product

Resources

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

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