Preliminary geologic map of the Mount Hayes quadrangle, eastern Alaska Range, Alaska

Nokleberg, Warren J.; Aleinikoff, John N.; Lange, Ian M.; Silva, S.R.; Miyaoka, R.T.; Schwab, Carl E.; Zehner, Richard E.; Bond, Gérard C.; Richter, D.H.; Smith, T.E.; Stout, J.H.

doi:10.3133/ofr92594

Cited by 34 publications

(50 citation statements)

References 13 publications

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“…However, the tectonic history and structural relation to the northern foothills fold-thrust belt and/or the Denali fault system remain unclear. Nokleberg et al (1992) provide additional map documentation of the McGinnis Glacier fault, and also map the Trident Glacier fault as displacing Nenana Gravel-like deposits, indicating Quaternary activity of this fault.…”

Section: Transition Zone Between the Western And Eastern Northern Foomentioning

confidence: 92%

“…Most geologic mapping of the northern foothills between the Wood and Delta rivers of the Alaska Range has been published at 1:250,000 scale (Csejtey et al, 1992;Nokleberg et al, 1992), and as a result, only captured some of the basic details of possible Quaternary deformation. What is clear from this previous mapping is that the major east-west-trending anticlines of the western northern foothills fold-thrust belt (Fig.…”

Section: Transition Zone Between the Western And Eastern Northern Foomentioning

confidence: 99%

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The Quaternary thrust system of the northern Alaska Range

Bemis¹,

Carver²,

Koehler³

2012

Geosphere

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Section: Transition Zone Between the Western And Eastern Northern Foomentioning

confidence: 92%

Section: Transition Zone Between the Western And Eastern Northern Foomentioning

confidence: 99%

The Quaternary thrust system of the northern Alaska Range

Bemis¹,

Carver²,

Koehler³

2012

Geosphere

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“…Cretaceous units of oceanic plateau provenance (Nokleberg et al, 1994) and complicated intrusive and extrusive igneous rocks of the Cantwell Formation (Nokleberg et al, 1992) which likely have higher seismic velocities than the Mesozoic sedimentary rocks.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Ten kilometer vertical Moho offset and shallow velocity contrast along the Denali fault zone from double-difference tomography, receiver functions, and fault zone head waves

et al. 2017

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Please cite this article as: A.A. Allam, V. Schulte-Pelkum, Y. Ben-Zion, C. Tape, N. Ruppert, Z.E. Ross , Ten kilometer vertical Moho offset and shallow velocity contrast along the Denali fault zone from double-difference tomography, receiver functions, and fault zone head waves, Tectonophysics (2017Tectonophysics ( ), doi: 10.1016Tectonophysics ( /j.tecto.2017 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T AbstractWe examine the structure of the Denali fault system in the crust and upper mantle using double-difference tomography, P-wave receiver functions, and analysis (spatial distribution and moveout) of fault zone head waves. The three methods have complementary sensitivity; tomography is sensitive to 3D seismic velocity structure but smooths sharp boundaries, receiver functions are sensitive to (quasi) horizontal interfaces, and fault zone head waves are sensitive to (quasi) vertical interfaces. The results indicate that the Mohorovičić discontinuity is vertically offset by 10 to 15km along the central 600km of the Denali fault in the imaged region, with the northern side having shallower Moho depths around 30km. An automated phase picker algorithm is used to identify ~1400 events that generate fault zone head waves only at near-fault stations.At shorter hypocentral distances head waves are observed at stations on the northern side of the fault, while longer propagation distances and deeper events produce head waves on the southern side. These results suggest a reversal of the velocity contrast polarity with depth, which we confirm by computing average 1D velocity models separately north and south of the fault. Using teleseismic events with M>=5.1, we obtain 31,400 P receiver functions and apply common- km to the north. To the east, this offset follows the Totschunda fault, which ruptured during the M7.9 2002 earthquake, rather than the Denali fault itself. The combined results suggest that the Denali fault zone separates two distinct crustal blocks, and that the Totschunda and Hines Creeks segments are important components of the fault and Cretaceous-aged suture zone structure.

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“…All rocks located south of the Hines Creek fault are considered part of the Alaska Range. Geology from Beikman (1994), Csejtey et al (1992), and Nokleberg et al (1992). warming and cooling events that have been documented throughout the northern Pacific region in both nonmarine and marine environments (e.g., Wolfe et al 1966;Miller et al 1987;Barron and Baldauf 1990;White and Ager 1994;Wolfe 1994;White et al 1997). The extensive floristic record of the Healy Creek basin permits estimates of changes in mean annual temperature and precipitation during deposition of the Usibelli Group .…”

Section: Introductionmentioning

confidence: 99%

Petrology and provenance of the Neogene Usibelli Group and Nenana Gravel; implications for the denudation history of the central Alaska Range

Ridgway

Trop

Jones

1999

Journal of Sedimentary Research

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Neogene basins exposed along the north-central flank of the Alaska Range record the geologic development of the highest mountain range in North America. Strata from these basins consist of the Miocene Usibelli Group (ϳ 600 m thick) and the Pliocene Nenana Gravel (ϳ 1000 m thick). Petrographic analyses of 54 sandstone thin sections and 36 conglomerate clast counts from one of these basins, the Healy Creek basin, delineate two distinct petrofacies. A stratigraphically older, quartz-rich petrofacies defines the Healy Creek, Suntrana, and Lignite Creek Formations of the Usibelli Group. A stratigraphically younger, lithic-rich petrofacies defines the Nenana Gravel. Sandstones of the lower petrofacies are characterized by a dominance of quartz (Q 60 F 27 L 12 ; Qm 33 F 28 Lt 39 ) and a high proportion of polycrystalline quartz (Qp 68 Lvm 21 Lsm 11 ). Schist and quartz clasts are common in conglomerates from this petrofacies. Imbricated conglomerate clasts and planar cross-stratification indicate southward to southwestward paleoflow for this quartz-rich petrofacies. Relative to the lower petrofacies, sandstones of the upper petrofacies are defined by a dominance of lithic fragments (Q 39 F 19 L 43 ; Qm 16 F 21 Lt 63 ), a lower proportion of polycrystalline quartz, and a higher proportion of volcanic lithic fragments (Qp 37 Lvm 55 Lsm 8 ). Conglomerate clast compositions in this petrofacies consist mainly of sedimentary and igneous clasts. This lithicrich petrofacies is dominated by northward paleocurrent indicators. The compositional and paleocurrent data of the Usibelli Group and Nenana Gravel suggest a regional paleodrainage reversal from southward-flowing fluvial systems transporting sediment from the quartzrich, metamorphic Yukon-Tanana terrane, to northward-flowing fluvial systems transporting sedimentary and igneous detritus from the growing Alaska Range.Superimposed on the first-order tectonic signal are second-order compositional differences. These differences may be related to a combination of factors but appear to be consistent with well documented changes in paleoclimate. For example, sandstones deposited during the warmest and wettest paleoclimates are characterized by a relative enrichment in quartz, especially polycrystalline quartz (Healy Creek Formation, Q 81 F 16 L 3 , Qp 93 Lvm 3 Lsm 4 ; Suntrana Formation, Q 61 F 25 L 14 , Qp 66 Lvm 25 Lsm 9 ). Sandstones deposited during cooler and drier climates, in contrast, have lower proportions of quartz and higher proportions of feldspar and lithic fragments (Lignite Creek Formation, Q 45 F 33 L 14 , Qp 56 Lvm 28 Lsm 17 ). Our analysis cannot account for all the possible influences on sandstone compositions during deposition of the Usibelli Group, but we contend that the apparent correlation between sandstone composition and changes in paleoclimate suggest that climatic modification of sandstone composition may have been significant.

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Preliminary geologic map of the Mount Hayes quadrangle, eastern Alaska Range, Alaska

Cited by 34 publications

References 13 publications

The Quaternary thrust system of the northern Alaska Range

The Quaternary thrust system of the northern Alaska Range

Ten kilometer vertical Moho offset and shallow velocity contrast along the Denali fault zone from double-difference tomography, receiver functions, and fault zone head waves

Petrology and provenance of the Neogene Usibelli Group and Nenana Gravel; implications for the denudation history of the central Alaska Range

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