Alleghanian orogen
44
Citation
220
Reference
10
Related Paper
Citation Trend
Abstract:
Includes 14 chapters on the Appalachian orogen, 15 of the Ouachita orogen, and a chapter on the connection between them beneath the eastern Gulf Coastal Plain. The Appalachian chapters synthesize the geologic development of the orogen by tectonostratigraphic intervals (pre-orogenic, Taconic, Acadian, Alleghanian, and post-Alleghanian), and also treat Paleozoic paleontologic control, regional geophysics, thermal history of the crystalline terranes, parts of the orogen buried beneath the Atlantic and eastern Gulf coastal plains, regional geomorphology, mineral and energy resources; an integration chapter also is included. The Ouachita chapters cover physical stratigraphy and biostratigraphy of the Paleozoic rocks, structural geology, a synthesis of the subsurface geology beneath the western Gulf Coastal Plain, a review of the mineral and energy resources, regional geophysics, and a tectonic synthesis. Twelve excellent plates provide four-color geologic maps, structural cross sections, tectonic syntheses, and geophysical maps; a black-and-white synthesis of Appalachian mineral deposits, and a reflection seismic cross section.Keywords:
Mineral resource classification
Geologic map
The Kootenay Arc in northeastern Washington and southeastern British Columbia contains the transition between autochthonous Upper Proterozoic to lower Paleozoic miogeoclinal strata and outboard Paleozoic to Mesozoic eugeoclinal terranes of uncertain paleogeographic affinity. To better understand the nature of this transition, U–Pb detrital zircon geochronologic studies were carried out on Upper Proterozic and lower Paleozoic sedimentary units in the Kootenay Arc, including miogeoclinal strata of the Horsethief Creek and Hamill groups and eugeoclinal strata of the Broadview and Ajax formations (Lardeau Group) and Daisy Formation (Covada Group). The results indicate that all units sampled are derived from source terranes of ~1.7 to 2.7 Ga, with notable populations of 1.76–1.85, 1.9–2.1, and 2.5–2.7 Ga zircons. These results are consistent with derivation of both the miogeoclinal and lower Paleozoic eugeoclinal units from adjacent portions of the southern Alberta craton. This extends the western limit of supracrustal rocks of known North American affinity, formed approximately in situ in the southern Canadian Cordillera, to outboard of the lower Paleozoic eugeoclinal strata in the Kootenay Arc.
Geochronology
Continental arc
Island arc
Cite
Citations (26)
Rocks of the eastern Klamath terrane (Redding section) in northern California record deposition, magmatism, and tectonism in an island-arc setting. Volcanism and sedimentation persisted for more than 220 m.y., spanning Devonian to Middle Jurassic time, and yielding thick successions of water-laid volcanic debris and lavas, with interstratified carbonate and clastic sequences. This study focuses on the upper Paleozoic rocks within the section. The oldest rocks studied, within the Upper Devonian(?) and Mississippian Brag-don Formation, contain epiclastic debris that was deposited in a submarine-fan setting. Sandstone compositions indicate that quartzose sedimentary and metasedimentary rocks formed the source area for epiclastic debris and that volcanism persisted throughout sedimentation. Transitional shallow-water facies in the upper part of the Bragdon interfinger with the overlying Baird Formation, which contains abundant volcanic debris. Volcanogenic shelf and strandline deposits characterize the lower part of the formation, and volcaniclastic turbidites characterize the upper part. The Baird Formation is locally interfingered with the overlying Lower Permian McCloud Limestone, which records two stages of Early Permian carbonate platform development: early Wolfcampian and late Wolfcampian to early Leonardian. Only the younger of the two platforms is present within the study area, and it contains more distal facies than those preserved to the south. The strata contain abundant fusulinids and corals which provide age constraints for carbonate-platform development and form the basis for regional biogeographic correlation. The time-transgressive Upper Permian Bollibokka Group (Nosoni and Dekkas Formations) succeeds the McCloud Limestone, comprising thick sequences of volcanogenic debris, intercalated lava, and, in the upper part, lenses of shallow-water limestone. The Upper Permian strata reflect volcanism and rapid subsidence within the are. All upper Paleozoic units were intruded by small gabbroic bodies and diabase dikes which may be partly cogenetic with Upper Permian basalts in the upper Dekkas Formation. The upper Paleozoic succession records local pulses of magmatism and variable subsidence rates within the eastern Klamath arc. Mississippian epiclastic rocks reflect uplift of the volcanic-arc basement, which contained rocks similar to those now exposed in the adjacent Yreka terrane or Shoo Fly Complex. Pulses in volcanism were restricted to mid-Carboniferous and Late Permian time. Diminished volcanism during the Early Permian allowed development of carbonate platforms. Rapid fluctuations of sedimentation and sub-sidence rates; pronounced lateral facies and age variations; accumulation of thick, volcanic-debris aprons during episodic volcanism; and sporadic persistence of volcanism during apparent lulls characterized deposition within this succession and are common processes in modern volcanic arcs. The stratigraphic record is composed predominantly of volcanogenic rocks and lesser carbonates, reflecting events and processes within the arc itself. Evidence for nearby basins or landmasses is sparse. The Mississippian epiclastic rocks, however, which were derived from the arc basement, reflect an ultimate sialic crustal source. Comparison of volcanic-arc evolution with the late Paleozoic evolution of continental margin and basinal rocks to the east indicates possible paleogeo-graphic ties between the eastern Klamath volcanic arc and rocks of the Golconda allochthon or the North American continent.
Sedimentation
Cite
Citations (31)
Margin (machine learning)
Cite
Citations (19)
Devonian
Laurasia
Red beds
Outcrop
Cite
Citations (21)
Basement
Geologic map
Orogeny
Cite
Citations (39)
Research Article| October 01, 1997 Paleomagnetism of Paleozoic strata of the Alexander terrane, southeastern Alaska Robert F. Butler; Robert F. Butler 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar George E. Gehrels; George E. Gehrels 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar David R. Bazard David R. Bazard 2Science Department, College of the Redwoods, Eureka, California 95501 Search for other works by this author on: GSW Google Scholar Author and Article Information Robert F. Butler 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 George E. Gehrels 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 David R. Bazard 2Science Department, College of the Redwoods, Eureka, California 95501 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1997) 109 (10): 1372–1388. https://doi.org/10.1130/0016-7606(1997)109<1372:POPSOT>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Robert F. Butler, George E. Gehrels, David R. Bazard; Paleomagnetism of Paleozoic strata of the Alexander terrane, southeastern Alaska. GSA Bulletin 1997;; 109 (10): 1372–1388. doi: https://doi.org/10.1130/0016-7606(1997)109<1372:POPSOT>2.3.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 Paleomagnetic samples were collected from 180 sites (sedimentary horizons or igneous flows) in nine Paleozoic formations of the Alexander terrane on or near Prince of Wales Island in southeastern Alaska. Analysis of samples collected from 68 sites within 2 stratigraphic sections of red sedimentary rocks from the Lower Devonian Karheen Formation allows determination of a characteristic component with unblocking temperatures between 550 °C and 680 °C in many samples. Site-mean characteristic directions from 29 sites pass fold and reversal tests and define polarity zones correlative between the two stratigraphic sections. These paleomagnetic data indicate an Early Devonian paleolatitude of 14° ± 4° (north or south). Geochronologic analysis of detrital zircon grains from the Karheen Formation requires that the Alexander terrane was adjacent to a continent with crust distributed within 1.6–1.8 Ga and 1.45–1.6 Ga age intervals. Early Paleozoic locations as part of the Australian paleo-Pacific margin of Gondwana or the Scandinavian margin of Baltica are consistent with the paleomagnetic, geologic, and geochronologic data, and available paleontologic data favor the Baltica paleoposition. The Lower Permian Halleck Formation volcanic rocks contain a stable paleomagnetism indicating a paleolatitude of approximately 25°N, consistent with the 25°N–30°N Permian paleolatitudes determined from three other formations of the Alexander-Wrangellia terranes. The 10°–20° paleolatitudes determined from numerous paleomagnetic studies of Late Triassic igneous rocks from Alexander-Wrangellia are almost certainly Northern Hemisphere paleolatitudes. Available evidence indicates: (1) early Paleozoic development of the Alexander terrane as a volcanic arc without significant incorporation of continental crust; (2) mid-Paleozoic juxtaposition with a continent containing 1.6–1.8 Ga and 1.45–1.6 Ga crust, probably the Scandinavian margin of Baltica; (3) rifting from that margin in Devonian time followed by tectonic transport to 25°–30° latitude in the northern paleo-Pacific by Permian time; and (4) southward motion to a Late Triassic paleolatitude of 10°–20° followed by accretion to North America with subsequent dispersal of fragments from northern Oregon to southern Alaska.The Ordovician Descon Formation, Silurian Heceta Limestone, Devonian Port Refugio Formation, and Pennsylvanian Ladrones Formation did not yield primary magnetizations. Upper Paleozoic carbonate rocks and siliciclastic strata of the Devonian Wadleigh Limestone and the Mississippian Peratrovich and Pennsylvanian Klawak Formations have characteristic magnetizations that are complex and, in part, demonstrably secondary. Rock-magnetic investigations of the Peratrovich Formation and the Wadleigh Limestone reveal wasp-waisted hysteresis loops with parameters closely matching those of other carbonate rocks known to have undergone chemical remagnetization. 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.
George (robot)
Cite
Citations (51)
飛騨外縁帯九頭竜周-伊勢川上流地域の中部古生界は,炭酸塩粒子に富む凝灰質砕屑岩からなる影路層(新称),砕屑岩を主体とする子馬巣谷層(新称)および主に石灰岩からなる上穴馬層(再定義)に区分できる.放散虫化石に基づき,影路層の年代は前期シルル紀の前期,子馬巣谷層は後期シルル紀~前期デボン紀の後期である.上穴馬層は福地層との対比から前期デボン紀である.飛騨外縁帯の他地域の中部古生界との対比から,これら各層は年代,岩相および岩相層序の組み合わせにおいて福地-一重ヶ根地域の中部古生界と類似し,本郷-荒城川および楢谷地域の中部古生界とは相違点が多いといえる.また,九頭竜周-伊勢川上流地域の下部デボン系には,ほぼ同時代の浅海相と深海~半深海相が存在することが明らかになった.こうした同時異相の存在は,飛騨外縁帯中部古生界の岩相層序の差異が,分化した堆積盆で形成されたことに起因する可能性があることを示す.
Cite
Citations (24)
The Paleozoic geologic history of Nevada can be viewed in terms of tectonic domains derived from the newly interpreted digital geologic map of Nevada. These domains reveal that Paleozoic tectonic events were shaped by complex interactions between the continental margin in Nevada and accreted terranes outboard of the margin.
Margin (machine learning)
Continental Margin
Geologic map
Passive margin
Cite
Citations (24)