Northern Terrane Research Articles

The Denali fault system and the tectonic development of Southern Alaska

The Denali fault system forms an arc, convex to the north, across southern Alaska. In the central Alaska Range, the system consists of a northern Hines Creek strand and a southern McKinley strand, up to 30 km apart. The Hines Creek fault may preserve a record of the early history of the fault system. Strong contrasts between juxtaposed lower Paleozoic rocks appear to require large dextral strike-slip or a combination of dipslip and strike-slip displacements along this fault. Thus the fault system may mark a reactivated suture zone between continental rocks to the north and a late Paleozoic island arc to the south, as suggested by Richter and Jones (1973). Major movements on the Hines Creek fault ceased by the Late Cretaceous, but local dip-slip movements continued into the Cenozoic. The McKinley fault is an active dextral strike-slip fault with a mean Holocene displacement rate of 1–2 cm/y. Post-Late Cretaceous dextral offset on this fault is probably at least 30 km and possibly as great as 400 km. Patterns of early Tertiary folding and reverse faulting indicate that the McKinley fault was active at that time and suggest that this fault developed shortly after strike-slip activity ceased on the Hines Creek fault. Oligocene — middle Miocene tectonic stability and late Miocene—Pliocene uplift of crustal blocks may reflect periods of quiescence and activity, on the McKinley fault. The two strands of the Denali fault divide the central Alaska Range into northern, central, and southern terranes. During the Paleozoic—Mesozoic there is evidence for at least two episodes of compressive deformation in the northern terrane, four in the central terrane, and two in the southern. During each, the axis of maximum compressive strain was subhorizontal and about north—south. This pattern suggests a Paleozoic and Mesozoic setting dominated by plate convergence, despite the possible large pre-Late Cretaceous lateral movement on the Hines Creek fault. The Cenozoic pattern of faulting and folding appears compatible with a plate tectonic model of (1) rapid northward movement of the Pacific plate relative to Alaska during the early Tertiary; (2) slow northwestward movement of the Pacific plate during the Oligicene and (3) rapid northwestward movement of the Pacific plate from the end of the Oligocene to the present.

Structural geology of the Nenana River segment of the Denali fault system, central Alaska Range

Research Article| September 01, 1977 Structural geology of the Nenana River segment of the Denali fault system, central Alaska Range ROBERT G. HICKMAN; ROBERT G. HICKMAN 1Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 95706 Search for other works by this author on: GSW Google Scholar CAMPBELL CRADDOCK; CAMPBELL CRADDOCK 1Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 95706 Search for other works by this author on: GSW Google Scholar KIRK W. SHERWOOD KIRK W. SHERWOOD 1Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 95706 Search for other works by this author on: GSW Google Scholar Author and Article Information ROBERT G. HICKMAN 1Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 95706 CAMPBELL CRADDOCK 1Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 95706 KIRK W. SHERWOOD 1Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 95706 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1977) 88 (9): 1217–1230. https://doi.org/10.1130/0016-7606(1977)88<1217:SGOTNR>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 MailTo Tools Icon Tools Get Permissions Search Site Citation ROBERT G. HICKMAN, CAMPBELL CRADDOCK, KIRK W. SHERWOOD; Structural geology of the Nenana River segment of the Denali fault system, central Alaska Range. GSA Bulletin 1977;; 88 (9): 1217–1230. doi: https://doi.org/10.1130/0016-7606(1977)88<1217:SGOTNR>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 The Denali fault system, one of the major tectonic elements of southern Alaska, forms an arc 2,100 km long across southern Alaska. In the central Alaska Range, the system consists of a northern Hines Creek strand and a southern McKinley strand, 30 km apart, which divide the area into northern, central, and southern terranes. There is evidence for at least two episodes of deformation in the northern terrane, four in the central, and two in the southern during Paleozoic and Mesozoic time. During each, the inferred axis of maximum compressive strain was subhorizontal and about north-south, but the direction shifted to north-northwest–south-southeast during a late Paleocene–Eocene folding episode. Tectonic stability during Oligocene–middle Miocene time was followed by differential uplift of crustal blocks during late Miocene–Pliocene time.The Hines Creek fault may preserve a record of the early history of the fault system. Strong contrasts between lower and middle Paleozoic rocks juxtaposed along the fault suggest large dextral strike-slip displacement, but major convergent movement cannot be ruled out. Movement throughout the Hines Creek fault ceased by middle Cretaceous time, but local dip-slip movements continued into the Cenozoic era. The McKinley fault is an active dextral strike-slip fault, with Cenozoic offset of probably at least 30 km and possibly much greater. Mean Holocene displacement rates are 1 to 2 cm/yr. These rates would produce a 30-km offset in 1.5 to 3.0 m.y., or a 400-km offset in 20 to 40 m.y.The Denali fault may be part of a transform fault system connecting the Juan de Fuca Ridge and the landward extension of the Aleutian subduction zone. However, it is more likely that the fault forms the northern boundary of a small lithospheric plate caught between the Pacific and American plates. 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.