Alaska coal geology, resources, and coalbed methane potential

Flores, Romeo M.; Stricker, Gary D.; Kinney, Scott A.

doi:10.3133/ds77

Cited by 26 publications

(13 citation statements)

References 20 publications

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“…The higher heat flow may be important for petroleum and coal maturation processes in modified forearc basins. The southern Alaska forearc basin system, for example, contains both petroleum and coal resources (Magoon, 1994;Wahrhaftig et al, 1994;Flores et al, 2004). Additional study of the stratigraphic record from other forearc basins that have experienced spreading ridge subduction is needed to fully document the effects of this process on basin development.…”

Section: Discussionmentioning

confidence: 99%

“…This basin is bounded by the Aleutian arc to the northwest and the Chugach accretionary prism to the southeast and is filled with Cenozoic nonmarine strata that are about 10,000 m thick (Fig. 16.3; Flores et al, 2004). Paleogene strata of the Cook Inlet forearc basin are about 2,500 m thick, whereas mainly Neogene strata are much thicker (7,500 m) and contain coal seams up to 15 m thick (Figs.…”

Section: Basin Development and Volcanism Around A Flat-slab Perimetermentioning

confidence: 99%

“…Upper Cretaceous-Cenozoic stratigraphy of sedimentary basins in south-central Alaska, and changes in subduction parameters along the southern margin of Alaska (1:Flores et al, 2004; 2, 3: Trop and Ridgway, 2007; 4: …”

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confidence: 99%

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Modification of Continental Forearc Basins by Flat‐Slab Subduction Processes: A Case Study from Southern Alaska

Ridgway

Trop

Finzel

2011

Tectonics of Sedimentary Basins

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Forearc basins are large sediment repositories that develop in the upper plate of convergent margins and are a direct response to subduction. These basins are part of the magmatic arc-forearc basin-accretionary prism "trinity" that defines the tectonic configuration of the upper plate along most subduction-related convergent margins. Many previous studies of forearc basins have explored the links between construction of magmatic arcs, exhumation of accretionary prisms, and sediment deposition in adjacent forearc basins. These studies provide an important framework for understanding firstorder tectonic processes recorded in forearc basins that are characterized by long-lived subduction of "normal" oceanic crust. Many convergent margins, however, are complicated by second-order subduction processes, such as flat-slab subduction of buoyant oceanic crust in the form of seamounts, spreading and aseismic ridges, and oceanic plateaus. These second-order processes can substantially modify the tectonic configuration of the upper plate both in time and space, and produce sedimentary basins that do not easily fit into the conventional magmatic arc-forearc basin-accretionary prism trinity.In this chapter, we discuss the modification of the southern Alaska forearc basin by Paleocene-Eocene subduction of a spreading ridge followed by OligoceneHolocene subduction of thick oceanic crust. This thick oceanic crust is currently being subducted beneath south-central Alaska and has an imaged maximum thickness of 30 km at the surface and 22 km at depth. Findings from southern Alaska suggest that forearc basins modified from flat-slab subduction processes may contain a sedimentary and volcanic stratigraphic record that differs substantially from typical forearc basins. Processes and sedimentary features that characterize modified forearc basins include the following: (1) flat-slab subduction of a buoyant, topographically elevated spreading ridge oriented subparallel to the margin prompts diachronous uplift of the forearc basin floor and exhumation of older marine forearc basin strata as the ridge is subducted. Passage of the spreading ridge leads to subsidence and renewed deposition of nonmarine sedimentary and volcanic strata that locally exceeds the thickness of the underlying marine strata. (2) Insertion of a slab window beneath the forearc basin during spreading ridge subduction produces local intrabasinal topographic highs with adjacent depocenters, as well as discrete volcanic centers within and adjacent to the forearc basin. (3) Flat-slab subduction of thick oceanic crust also results in surface uplift and exhumation of forearc basin sedimentary strata. However, the insertion of thick crust throughout the flat-slab region (i.e., lack of a slab window) inhibits subduction-related magmatism adjacent to the forearc basin. In the case of subduction of a >350-km-wide fragment of thick oceanic crust beneath south-central Alaska, exhumation of forearc basin strata located above the region of flat-slab subduction has prompted enhanced T...

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Section: Discussionmentioning

confidence: 99%

Section: Basin Development and Volcanism Around A Flat-slab Perimetermentioning

confidence: 99%

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Modification of Continental Forearc Basins by Flat‐Slab Subduction Processes: A Case Study from Southern Alaska

Ridgway

Trop

Finzel

2011

Tectonics of Sedimentary Basins

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“…3; Magoon et al, 1976b;Wolfe and Tanai, 1980). This unit forms a sheet ~200 m thick across most of the basin, with a maximum thickness of ~845 m (Flores et al, 2004). The conglomerate and conglomeratic sandstone in this formation were deposited in fluvial and deltaic environments near the basin margins that graded into estuarine depositional systems along the basin center, similar to modern environments in the Cook Inlet basin (Kirschner and Lyon, 1973;Boss et al, 1976;Detterman et al, 1976;Hite, 1976;Magoon and Egbert, 1986).…”

Section: Cook Inlet Basin Stratigraphymentioning

confidence: 99%

Provenance signature of changing plate boundary conditions along a convergent margin: Detrital record of spreading-ridge and flat-slab subduction processes, Cenozoic forearc basins, Alaska

2015

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Cenozoic strata from forearc basins in southern Alaska record deposition related to two different types of shallow subduction: Paleocene-Eocene spreading-ridge subduction and Oligocene-Recent oceanic plateau subduction. We use detrital zircon geochronology (n = 1368) and clast composition of conglomerate (n = 1068) to reconstruct the upper plate response to these two subduction events as recorded in forearc basin strata and modern river sediment. Following spreading-ridge subduction, the presence of Precambrian and Paleozoic detrital zircon ages in middle Eocene-lower Miocene arc-margin strata and Early Cretaceous ages in lower Miocene accretionary prism-margin strata indicates that sediment was transported to the basin from older terranes in interior Alaska and from the exhumed eastern part of the Cretaceous forearc system, respectively. By middle-late Miocene time, diminished abundances of these populations reflect shallow subduction of an oceanic plateau and associated exhumation that resulted in an overall contraction of the catchment area for the forearc depositional system.In the southern Alaska forearc basin system, upper plate processes associated with subduction of a spreading ridge resulted in an abrupt increase in the diversity of detrital zircon ages that reflect new sediment sources from far inboard regions. The detrital zircon signatures from strata deposited during oceanic plateau subduction record exhumation of the region above the flat slab, with the youngest detrital zircon population reflecting the last period of major arc activity prior to inser-tion of the flat slab. This study provides a foundation for new tectonic and provenance models of forearc basins that have been modified by shallow subduction processes, and may help to facilitate the use of U-Pb dating of detrital zircons to better understand basins that formed under changing geodynamic plate boundary conditions. ., 2015, Provenance signature of changing plate boundary conditions along a convergent margin: Detrital record of spreading-ridge and flat-slab subduction processes, Cenozoic forearc basins, Alaska: Geosphere, v. 11, no. 3,

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“…In 2007, the BGR made yet another upward revision, increasing world hard coal resources by 68% and lignite resources by 36%. This was explained by the addition of newly measured, indicated, inferred, and hypothetical coal resources in Alaska identified by a USGS study [79].…”

Section: Historical Supply Assessmentsmentioning

confidence: 99%

Global coal production outlooks based on a logistic model

Höök

Zittel

Schindler

et al. 2010

Fuel

160

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A small number of nations control the vast majority of the world's coal reserves. The geologically available amounts of coal are vast, but geological availability is not enough to ensure future production since economics and restrictions also play an important role. Historical trends in reserve and resource assessments can provide some insight about future coal supply and provide reasonable limits for modelling. This study uses a logistic model to create long-term outlooks for global coal production. A global peak in coal production can be expected between 2020 and 2050, depending on estimates of recoverable volumes. This is also compared with other forecasts. The overall conclusion is that the global coal production could reach a maximum level much sooner than most observers expect.

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Alaska coal geology, resources, and coalbed methane potential

Cited by 26 publications

References 20 publications

Modification of Continental Forearc Basins by Flat‐Slab Subduction Processes: A Case Study from Southern Alaska

Modification of Continental Forearc Basins by Flat‐Slab Subduction Processes: A Case Study from Southern Alaska

Provenance signature of changing plate boundary conditions along a convergent margin: Detrital record of spreading-ridge and flat-slab subduction processes, Cenozoic forearc basins, Alaska

Global coal production outlooks based on a logistic model

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