The Spieden Group: an anomalous piece of the Cordilleran paleogeographic puzzle

1981 ◽  
Vol 18 (11) ◽  
pp. 1694-1707 ◽  
Author(s):  
Samuel Y. Johnson
Keyword(s):  
Large Scale ◽  
Upper Jurassic ◽  
Alluvial Fan ◽  
San Juan ◽  
Island Formation ◽  
Shallow Marine ◽  
San Juan Islands ◽  
Structural Style ◽  
Lower Member ◽  
Volcanic Source

Spieden and Sentinel Islands, San Juan Islands, Washington, are underlain by the only known occurrence of the Spieden Group, composed of the Upper Jurassic (Oxfordian or Kimmeridgian) Spieden Bluff Formation and the Lower Cretaceous (Valanginian and Hauterivian and possibly younger) Sentinel Island Formation, separated by a disconformity.The 100 m thick Spieden Bluff Formation is subdivided into two members: (1) an 80 m thick lower member, consisting of 5 m of sandstone, siltstone, and tuff overlain by 75 m of volcanic breccia–conglomerate largely of debris flow (laharic?) origin; and (2) a 20 m thick upper member consisting of fossiliferous sandstone and siltstone deposited on a shallow marine slope. Sedimentologic, petrologic, and geochronologic data suggest that sediments of the Spieden Bluff Formation accumulated near an active volcanic source to the north contributing primarily andesite, dacite, and basaltic andesite.The 740 m thick Sentinel Island Formation is also subdivided into two members: (1) a 140 m thick lower member consisting of fossiliferous sandstone and siltstone deposited in a shallow marine environment; and (2) an unconformably overlying 600 m thick upper member consisting of volcanic conglomerate deposited as an alluvial fan. The source terrane for the Sentinel Island Formation was also primarily Upper Jurassic volcanic rocks and lay to the northeast.Rocks of equivalent age occur in the southern part of the San Juan Islands and in neighboring geologic provinces, but most of these correlative rocks differ from the Spieden in sedimentology, structural style, and metamorphism. Juxtaposition of the Spieden Group and these correlative rocks might have been accomplished by shortening and fragmentation of a regional convergent margin, by large-scale transport of allochthonous blocks, or by some combination of the two mechanisms.

Turonian (Upper Cretaceous) lithostratigraphy and biochronology, southern Gulf Islands, British Columbia, and northern San Juan Islands, Washington State

2005 ◽  
Vol 42 (11) ◽  
pp. 2001-2020 ◽  
Author(s):  
James W Haggart ◽  
Peter D Ward ◽  
William Orr
Keyword(s):  
British Columbia ◽  
Washington State ◽  
San Juan ◽  
Submarine Fan ◽  
Island Formation ◽  
Shallow Marine ◽  
San Juan Islands ◽  
Thrust System ◽  
Gulf Islands ◽  
Facies Succession

Clastic strata preserved on Sidney Island, Barnes Island, and adjacent islands of the southernmost Gulf Islands of British Columbia and the northern San Juan Islands of Washington State are assigned to new stratigraphic units: the Sidney Island Formation and the Barnes Island Formation. The Sidney Island Formation consists of basal conglomerate and sandstone that grades upward through planar-stratified sandstone into hummocky cross-stratified sandstone and siltstone, all of which are deposited in relatively shallow-marine environments. The Barnes Island Formation, in contrast, consists of deep-marine conglomerate, sandstone, and mudstone that was deposited in a submarine-fan setting. Mollusk fossils from the Sidney Island Formation are of Early to Middle Turonian age, whereas ammonites and foraminifers from the Barnes Island Formation indicate a Late Turonian age. The Sidney Island Formation thus records initial marine transgression and inundation of basement rocks, followed by basin deepening that is transitional to the deep-marine submarine-fan deposits of the Barnes Island Formation. Sidney Island Formation strata have been considered previously as derived from uplift along the nearby San Juan thrust system in mid-Cretaceous time. However, the shallow-marine strata are internally well organized, and the facies succession is persistent across the formation's outcrop area. In addition, the formation lacks the distinctive detrital metamorphic mineral assemblages that are characteristic of older rocks of the San Juan Islands. These observations suggest that strata of the Sidney Island Formation did not accumulate immediately adjacent to active thrusting but rather in a more distal setting relative to the thrust system.

Stratigraphy, depositional setting, and tectonic significance of the clastic cover to the Fidalgo Ophiolite, San Juan Islands, Washington

1988 ◽  
Vol 25 (3) ◽  
pp. 417-432 ◽  
Author(s):  
John Garver
Keyword(s):  
Sedimentary Cover ◽  
Hanging Wall ◽  
Upper Jurassic ◽  
San Juan ◽  
Island Formation ◽  
San Juan Islands ◽  
The North ◽  
Tectonic Significance ◽  
Tectonically Active ◽  
Depositional Setting

The San Juan Islands of northwest Washington State comprise a diverse assemblage of Paleozoic and Mesozoic terranes amalgamated during a regional Cretaceous orogenic event. Detailed tectono-stratigraphy of the sedimentary cover to the Fidalgo Complex indicates the presence of several stratigraphically distinct units, which are described and formalized in this paper. The Fidalgo Complex and its sedimentary cover are the structurally highest rocks in the San Juan thrust system.The Fidalgo Complex is a highly disrupted Middle to Upper Jurassic ophiolite with arc-related intrusives, volcanics, and sediments. The Trump unit is an informally named sequence of siliceous sediments, volcanic graywacke, and minor volcanics that occurs at the stratigraphically highest portion of the Fidalgo Complex. Complex facies, lithologies, and provenance indicate that deposition of this Oxfordian(?) to upper Tithonian unit occurred in an arc-proximal setting.The upper Tithonian and younger Lummi Group (elevated here) lies depositionally above the Fidalgo Complex; locally the contact is an angular unconformity. The James Island Formation (new) is designated as a lower unit of the Lummi Group in the Decatur Island area. The chert-rich volcaniclastic sediments of the James Island Formation, locally containing ophiolitic debris, represent submarine-fan deposition within a tectonically active basin where basement blocks were uplifted along fault scarps.Middle Cretaceous thrusting and lawsonite–prehnite–aragonite metamorphism predated deposition of the Obstruction Formation (new), which is inferred to unconformably overlie the Lummi Group – Fidalgo Complex. Metamorphism postdated the late Albian, as rocks of this age are metamorphosed. The Obstruction Formation (?Cenomanian–Turonian) does not have metamorphic lawsonite–prehnite–aragonite, which are characteristic of underlying terranes in the San Juan Islands. Instead, the Obstruction Formation contains clasts derived from underlying metamorphosed terranes in the San Juan Islands; some clasts show these high-pressure, low-temperature metamorphic minerals. The Obstruction Formation probably represents synthrusting sedimentation that occurred after the San Juan terranes were metamorphosed and rapidly brought to the surface by continued thrusting over a hanging-wall obstruction. Thrusting was most likely driven by the accretion of Wrangellia against the North American margin.

Diagenesis of the shallow marine Fulmar Formation in the Central North Sea

Clay Minerals ◽  
1986 ◽  
Vol 21 (4) ◽  
pp. 537-564 ◽  
Author(s):  
D. J. Stewart
Keyword(s):  
Clay Mineral ◽  
North Sea ◽  
Large Scale ◽  
Shear Zones ◽  
Upper Jurassic ◽  
Burial Diagenesis ◽  
Secondary Porosity ◽  
Shallow Marine ◽  
History Of ◽  
Central North Sea

AbstractThe diagenetic history of the Upper Jurassic Fulmar Formation of the Central North Sea is described with emphasis on the Fulmar Field. The Fulmar Formation was deposited on a variably subsiding shallow-marine shelf under the influence of halokinetic and fault movements. The sediments are extensively bio-destratified although large-scale cross-bedding is locally preserved. The dominant mechanism of deposition is thought to have been storm-generated currents. Soft-sediment deformation structures are common and are attributed to syn- and post-depositional dewatering of the sandstones. The dewatering was associated with fractures and shear zones which reflect tectonic instability resulting from periodic salt withdrawal and/or graben fault movements. The dewatering may have been initiated by repacking of the sediments during earth movements or by the gradual build-up and sudden release of overpressures due to compaction and/or clay mineral dehydration during rapid burial at the end of the Cretaceous. The formation is composed of arkosic sandstone of similar composition to Triassic sandstones from which it was probably derived. The sandstones also contain limited amounts of marine biogenic debris including sponge solenasters, bivalve shells, rare ammonites and belemnites. Initial diagenesis began with an environment-related phase during which quartz and feldspar overgrowths and chalcedony and calcite cements were precipitated. These cements appear to form concretions adjacent to local concentrations of sponge debris and shell debris, respectively, and were disturbed after their formation by fracturing and dewatering. This was followed by an early burial stage of diagenesis which resulted in extensive dolomite cementation and minor clay mineral authigenesis (illite and chlorite). The last phase of mineral growth was probably pyrite. During early burial diagenesis, secondary porosity after feldspar and/or carbonate was produced, although the exact timing is not clear. The lack of both stylolitic developments and extensive illitization indicates that the late burial diagenesis stage was never reached, although sufficient clay diagenesis occurred to destroy all traces of mixed-layer illite-smectite (present in some shallower wells). The main control on reservoir behaviour is primary depositional fabric. Diagenesis only overprints these controls. Locally-cemented fracture sets act as baffles to fluid flow, but they are not extensive and the reservoir acts as one unit.

Sequence-Based Lithofacies Paleogeography and Sandbody Distribution

2014 ◽  
Vol 608-609 ◽  
pp. 1071-1078
Author(s):  
An Ran Liu ◽  
Xiao Bin Wu ◽  
Jun Ren Hu
Keyword(s):  
Large Scale ◽  
Upper Jurassic ◽  
Alluvial Fan ◽  
Middle Section ◽  
Medium Term ◽  
Front Edge ◽  
Western Sichuan ◽  
Fan Delta ◽  
Western Sichuan Depression ◽  
Sand Bodies

Guided by the high-resolution sequence stratigraphy theories, the authors divided the Upper Jurassic Penglaizhen Formation in the middle section of western Sichuan depression of china into 2 long-term sequences (L1-L2) and 4 medium-term sequences (M1-M4) through comprehensive study of outcrops, coring, logging and seismic data. Sequence-based lithofacies and paleogeographic maps of Upper Jurassic Penglaizhen Formation were compiled by medium-term sequences as mapping units. The results showed that the front edge of Longmenshan developed with large-scale alluvial fans, fan delta sediment was a fan-delta group overlapped by several fan deltas at front edge of Longmenshan in period M1-M4.The dominated type of sedimentary system in middle section of western Sichuan depression was fan delta - shallow lake sediment in period M1-M2, alluvial fan was only changed in size and location; sand bodies were mainly distributed in front edge of Longmenshan and the Zhongjiang-Deyang region; In period M3-M4, it is changed into a large area of fan delta plain sediment with thick sand and big scale, sand bodies were mainly distributed in the Pixian-Wenjiang-Dayi area.

scholarly journals Regional Structural Style of the Central and Southern Oman Mountains: Jebel Akhdar, Saih Hatat, and the Northern Ghaba Basin

GeoArabia ◽  
1998 ◽  
Vol 3 (4) ◽  
pp. 475-490 ◽  
Author(s):  
Van S. Mount ◽  
Roderick I.S. Crawford ◽  
Steven C. Bergman
Keyword(s):  
Large Scale ◽  
Carbonate Platform ◽  
Great Distance ◽  
Reverse Fault ◽  
High Angle ◽  
Shallow Marine ◽  
Oman Mountains ◽  
Structural Style ◽  
Central Platform ◽  
Deformation Event

ABSTRACT Three quantitative regional transects across the Saih Hatat and Jebel Akhdar anticlines in the Central and Southern Oman Mountains and the Northern Ghaba Basin have been constructed based on surface, well and seismic data. Interpreted large-scale structural geometries suggest that the Saih Hatat and Jebel Akhdar anticlines are basement-involved compressional structures, underlain by north-dipping, high-angle, blind, reverse faults located beneath their southern limbs. A compressional deformation event initiated in the Oligocene (constrained by apatite fission track data) involving the high-angle reverse faults is interpreted in which pre-Permian strata and Permian-through-Lower Cretaceous strata, exposed in the Saih Hatat and Jebel Akhdar anticlines, were parautochthonous - uplifted over the underlying reverse faults, and not displaced a great distance laterally. The allochthonous Hawasina and Sumeini sedimentary rocks and the Semail Ophiolite complex are interpreted to have been emplaced onto the carbonate platform during the Late Cretaceous, and have subsequently been parautochthonous during the Tertiary deformation. The upper portion of the pre-Permian section in the Ghaba Basin consists predominantly of a thick (>4 kilometers) sequence of Cambrian-through-Silurian, predominantly non-marine to shallow-marine, clastics of the Haima Supergroup. In contrast, out of the Ghaba Basin proper in the Central Platform or Musallim High region, the Haima Supergroup is generally less than 2 kilometers thick, and interpreted to thin to the north. The fundamental difference in pre-Permian strata exposed in the Saih Hatat and Jebel Akhdar Anticline windows is the thick (>3.4 kilometers) section of Ordovician age, shallow-marine strata (Amdeh Formation) present in the Saih Hatat Anticline, but absent in the Jebel Akhdar Anticline. In our interpretation, the shallow-marine clastics exposed in the Saih Hatat Anticline represent the northern extension of the Early Paleozoic Ghaba Basin, which have been uplifted over a high-angle reverse fault in the Early Tertiary deformation event. The cross-section through Jebel Akhdar is located to the northwest of the Ghaba Salt Basin, along the Musallim High. In this area the thickness of the Ordovician strata deposited is interpreted to be less than in the Ghaba Basin. The Ordovician section is not present in the Jebel Akhdar structure - the thinned section likely eroded in a Late Paleozoic deformation event.

Sequence stratigraphy of source and reservoir rocks in the Upper Permian and Jurassic of Jameson Land, East Greenland

1998 ◽  
pp. 43-54 ◽  
Author(s):  
Lars Stemmerik ◽  
Gregers Dam ◽  
Nanna Noe-Nygaard ◽  
Stefan Piasecki ◽  
Finn Surlyk
Keyword(s):  
Sequence Stratigraphy ◽  
Middle Jurassic ◽  
Sedimentary Basins ◽  
Upper Jurassic ◽  
Oil Field ◽  
Source Rocks ◽  
Upper Permian ◽  
Shallow Marine ◽  
East Greenland ◽  
Reservoir Rocks

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stemmerik, L., Dam, G., Noe-Nygaard, N., Piasecki, S., & Surlyk, F. (1998). Sequence stratigraphy of source and reservoir rocks in the Upper Permian and Jurassic of Jameson Land, East Greenland. Geology of Greenland Survey Bulletin, 180, 43-54. https://doi.org/10.34194/ggub.v180.5085 _______________ Approximately half of the hydrocarbons discovered in the North Atlantic petroleum provinces are found in sandstones of latest Triassic – Jurassic age with the Middle Jurassic Brent Group, and its correlatives, being the economically most important reservoir unit accounting for approximately 25% of the reserves. Hydrocarbons in these reservoirs are generated mainly from the Upper Jurassic Kimmeridge Clay and its correlatives with additional contributions from Middle Jurassic coal, Lower Jurassic marine shales and Devonian lacustrine shales. Equivalents to these deeply buried rocks crop out in the well-exposed sedimentary basins of East Greenland where more detailed studies are possible and these basins are frequently used for analogue studies (Fig. 1). Investigations in East Greenland have documented four major organic-rich shale units which are potential source rocks for hydrocarbons. They include marine shales of the Upper Permian Ravnefjeld Formation (Fig. 2), the Middle Jurassic Sortehat Formation and the Upper Jurassic Hareelv Formation (Fig. 4) and lacustrine shales of the uppermost Triassic – lowermost Jurassic Kap Stewart Group (Fig. 3; Surlyk et al. 1986b; Dam & Christiansen 1990; Christiansen et al. 1992, 1993; Dam et al. 1995; Krabbe 1996). Potential reservoir units include Upper Permian shallow marine platform and build-up carbonates of the Wegener Halvø Formation, lacustrine sandstones of the Rhaetian–Sinemurian Kap Stewart Group and marine sandstones of the Pliensbachian–Aalenian Neill Klinter Group, the Upper Bajocian – Callovian Pelion Formation and Upper Oxfordian – Kimmeridgian Hareelv Formation (Figs 2–4; Christiansen et al. 1992). The Jurassic sandstones of Jameson Land are well known as excellent analogues for hydrocarbon reservoirs in the northern North Sea and offshore mid-Norway. The best documented examples are the turbidite sands of the Hareelv Formation as an analogue for the Magnus oil field and the many Paleogene oil and gas fields, the shallow marine Pelion Formation as an analogue for the Brent Group in the Viking Graben and correlative Garn Group of the Norwegian Shelf, the Neill Klinter Group as an analogue for the Tilje, Ror, Ile and Not Formations and the Kap Stewart Group for the Åre Formation (Surlyk 1987, 1991; Dam & Surlyk 1995; Dam et al. 1995; Surlyk & Noe-Nygaard 1995; Engkilde & Surlyk in press). The presence of pre-Late Jurassic source rocks in Jameson Land suggests the presence of correlative source rocks offshore mid-Norway where the Upper Jurassic source rocks are not sufficiently deeply buried to generate hydrocarbons. The Upper Permian Ravnefjeld Formation in particular provides a useful source rock analogue both there and in more distant areas such as the Barents Sea. The present paper is a summary of a research project supported by the Danish Ministry of Environment and Energy (Piasecki et al. 1994). The aim of the project is to improve our understanding of the distribution of source and reservoir rocks by the application of sequence stratigraphy to the basin analysis. We have focused on the Upper Permian and uppermost Triassic– Jurassic successions where the presence of source and reservoir rocks are well documented from previous studies. Field work during the summer of 1993 included biostratigraphic, sedimentological and sequence stratigraphic studies of selected time slices and was supplemented by drilling of 11 shallow cores (Piasecki et al. 1994). The results so far arising from this work are collected in Piasecki et al. (1997), and the present summary highlights the petroleum-related implications.

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