Middle and Late Eocene Great Australian Bight lithobiostratigraphy and stepwise evolution of the southern Australian continental margin

2003 ◽  
Vol 50 (1) ◽  
pp. 113-128 ◽  
Author(s):  
Q. Li ◽  
N. P. James ◽  
B. McGowran
Keyword(s):  
Continental Margin ◽  
Late Eocene ◽  
Great Australian Bight ◽  
Stepwise Evolution

The Upper Cretaceous foraminiferal record of IODP Site U1512 (Great Australian Bight, Indian Ocean)

2021 ◽  
Author(s):  
Erik Wolfgring ◽  
Michael A. Kaminski ◽  
Anna Waśkowska ◽  
Maria Rose Petrizzo ◽  
Eun Young Lee ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Ocean Circulation ◽  
Planktonic Foraminifera ◽  
Late Eocene ◽  
Foraminiferal Assemblage ◽  
Benthic Foraminiferal Assemblage ◽  
International Ocean Discovery Program ◽  
Foraminiferal Record ◽  
Great Australian Bight ◽  
Microfossil Assemblage

<p>Site U1512 was drilled during Expedition 369 of the International Ocean Discovery Program (IODP), which is located in the Great Australian Bight, southern Indian Ocean. It provides exceptional insights into the benthic foraminiferal biostratigraphy and paleoecology of a high southern latitude restricted marginal marine basin during the Late Cretaceous hot greenhouse climate and the rifting between Australia and Antarctica. The sedimentary sequence recovered at Site U1512 presents a rare record of a deep water agglutinated foraminifera (DWAF) community from the Southern High Latitudes. The Cretaceous record at Site U1512 covers the lower Turonian through Santonian (nannofossil zones UC8b to UC12/CC10b to CC16, <em>H. helvetica</em> to <em>Marginotruncana</em> spp. - <em>Planoheterohelix papula</em> - <em>Globotruncana linneana</em> planktonic foraminifera zones). Diverse benthic foraminiferal assemblages yield many new taxa that are yet to be described.</p><p>Agglutinated forms dominate the assemblage in most intervals. In lower to mid Turonian and Santonian strata, calcareous benthic as well as planktonic foraminifera are frequent. Abundant radiolaria are recovered from the mid Turonian, and they increase up-section and exceed 50% of the microfossil assemblage. We documented a diverse benthic foraminiferal assemblage consisting of 162 taxa (110 agglutinated and 52 calcareous). The most common taxa of the DWAF assemblage are tubular (i.e., <em>Kalamopsis grzybowskii,</em> <em>Bathysiphon</em> spp.) and planispiral forms (i.e., <em>Ammodiscus</em> spp., <em>Haplophragmoides</em> spp., <em>Buzasina</em> sp., <em>Labrospira</em> spp.).</p><p>The Turonian strata yield highly abundant <em>Bulbobaculites problematicus</em> and <em>Spiroplectammina navarroana</em>. The presence of the agglutinated foraminiferal marker taxa <em>Uvigerinammina jankoi</em> and <em>Bulbobaculites problematicus</em> provides a tie-point to the Tethyan DWAF biozonation of Geroch and Nowak (1984). The composition of foraminiferal assemblages and the increase in radiolaria abundance suggest unstable environmental conditions at Site U1512 during the early Turonian through Santonian. These characteristics refer to changes in bathymetry associated with changing ocean chemistry. Results of quantitative analyses of the benthic foraminiferal assemblages indicate a restricted paleoenvironmental regime, dictated by changes in paleobathymetry, unstable patterns in ocean circulation, and the discharge of a nearby river delta system.</p><p>References: Geroch, S., Nowak, K., 1984. Proposal of zonation for the Late Tithonian – late Eocene. based upon arenaceous Foraminifera from the Outer Carpathians, Poland, 225-239, In: Oertli, H.J. (Ed.), Benthos ´83; 2nd international 915 Symposium on Benthic Foraminifera, Pau (France) April 11-15, 1983, Elf Aquitaine, ESO REP and TOTAL CFP, Pau and Bordeaux.</p><p> </p>

Cenozoic sea-level and cryospheric evolution from deep-sea geochemical and continental margin records

2020 ◽  
Author(s):  
Kenneth Miller ◽  
James Browning ◽  
W. John Schmelz ◽  
Robert Kopp ◽  
Gregory Mountain ◽  
...  
Keyword(s):  
Sea Level ◽  
Continental Margin ◽  
Ice Sheets ◽  
Late Eocene ◽  
Temperature Record ◽  
Early Eocene ◽  
Last Deglaciation ◽  
Sea Level Changes ◽  
Bottom Water Temperature ◽  
Continental Scale

<p>Cenozoic (past ~66 Myr) sea-level history reflects temperature changes and cryospheric evolution of the Earth from essentially ice-free conditions in the Early Eocene to bipolar ice sheets in the Quaternary. We derived a global mean sea level (GMSL) estimate for the Cenozoic using a new astronomically calibrated Pacific benthic foraminiferal δ<sup>18</sup>O splice from published records and a 2 Myr-smoothed Pacific bottom water temperature record based on published benthic foraminiferal Mg/Ca data. Our GMSL estimates are similar to sea-level estimates derived from “backstripping” (progressively accounting for compaction, loading and thermal subsidence) of cores from the mid-Atlantic U.S. continental margin. Peak global warmth, elevated GMSL, high CO<sub>2</sub>, and largely ice-free conditions occurred during the Early Eocene “Hothouse.” During the Middle-Late Eocene “Cool Greenhouse,” small ice sheets associated with lower atmospheric CO<sub>2</sub> drove sea-level changes. Continental-scale ice sheets began in the Oligocene “Icehouse” (ca. 34 Ma), a permanent East Antarctic ice sheet began in the middle Middle Miocene (ca. 12.8 Ma), and full, bipolar glaciation began in the Quaternary (ca. 2.55 Ma). The Last Glacial Maximum (20-27 ka) was the largest lowering of GMSL (~130 m) of the Mesozoic-Cenozoic and GMSL rise during last deglaciation (ca. 19-10 ka) exceeded 40-45 mm/yr.  Sea-level rise progressively slowed from 10 ka to 2 ka and was then at stillstand until late 19<sup>th</sup> to early 20<sup>th</sup> century when rates began to rise. Despite large uncertainties in proxies, our study reaffirms that throughout the Cenozoic, high long-term (10<sup>7</sup>-year scale) CO<sub>2</sub> was associated with warm climates and high sea levels.  However, sea level-change was dominated by periodic, astronomically controlled (10’s kyr-Myr scale) Milankovitch variations superimposed upon longer-term changes driven by CO<sub>2</sub>.</p>

Sequence stratigraphy of a Mesozoic carbonate platform-to-basin system in western Sicily

2009 ◽  
Vol 1 (3) ◽  
Author(s):  
Luca Basilone
Keyword(s):  
Continental Margin ◽  
Carbonate Platform ◽  
Late Eocene ◽  
Late Triassic ◽  
Sedimentary Evolution ◽  
Subaerial Exposure ◽  
Platform Margin ◽  
Western Sicily ◽  
Physical Stratigraphy ◽  
Basin System

AbstractSequence stratigraphic studies of the Triassic through Paleogene carbonate successions of platform, slope and basin in western Sicily (Palermo and Termini Imerese Mountains) have identified a sedimentary cyclicity mostly caused by relative oscillations of sea level. The stratigraphic successions of the Imerese and Panormide palaeogeographic domains of the southern Tethyan continental margin were studied with physical-stratigraphy and facies analysis to reconstruct the sedimentary evolution of this platform-to-basin system.The Imerese Basin is characterized by a carbonate and siliceous-calcareous succession, 1200–1400m thick, Late Triassic to Eocene in age. The strata display a typical example of a carbonate platform margin, characterized by resedimented facies with progradational stacking patterns. The Panormide Carbonate Platform is characterized by a carbonate succession, 1000–1200 m thick, Late Triassic to Late Eocene, mostly consisting of shallow-water facies with periodic subaerial exposure.The cyclic arrangement has been obtained by the study of the stratigraphic signatures (unconformities, facies sequences, erosional surfaces and stratal geometries) found in the slope successions. The recognized pattern has been compared with coeval facies of the shelf. This correlation provided evidence of sedimentary evolution, influenced by progradation and backstepping of the shelf deposits.The stratigraphic architecture of the platform-to-basin system is characterized by four major transgressive/regressive cycles during the late Triassic to late Eocene.These cycles, framed in a chronostratigraphic chart, allows the correlation of the investigated shelf-to-basin system with the geological evolution of the African continental margin during the Mesozoic, showing tectono-eustatic cycles. The first cycle, encompassing the late Triassic to early Jurassic, appears to be related to the late syn-rift stage of the continental margin evolution. The following three cycles, spanning from the Jurassic to Eocene, can be related to the post-rift evolution and to thermal subsidence changes.

Continental margin of the Great Australian Bight

1970 ◽  
Vol 8 (1) ◽  
pp. 31-58 ◽  
Author(s):  
John R. Conolly ◽  
Alan Flavelle ◽  
Robert S. Dietz
Keyword(s):  
Continental Margin ◽  
Great Australian Bight

Tectonics and Depositional History of the Continental Margin Off Vancouver Island, British Columbia

1972 ◽  
Vol 9 (3) ◽  
pp. 280-296 ◽  
Author(s):  
D. L. Tiffin ◽  
B. E. B. Cameron ◽  
J. W. Murray
Keyword(s):  
Continental Margin ◽  
Deep Water ◽  
Depositional Environment ◽  
Marked Change ◽  
Vancouver Island ◽  
Late Eocene ◽  
Transform Faults ◽  
Depositional History ◽  
Seismic Profiling ◽  
History Of

Sampling and seismic profiling in the Tofino Basin west of Vancouver Island show there is a thick sequence of Tertiary rocks ranging in age from late Eocene to Pliocene. The rocks are mainly mudstones containing abundant foraminifera indicating a bathyal depositional environment throughout most of the Tertiary. Subsequent uplift has exposed the deep water sediments on the shelf over much of the area. Eocene-Oligocene sediments occur in a belt along the inner shelf, while Miocene and Pliocene rocks lie seaward of this. Pliocene rocks form a regressive sequence overlapping the older Tertiary, with the greatest thickness in the south.At least two major periods of deformation resulted in faulting, folding, and diapirism on the continental shelf. Deformational patterns show a marked change from north to south. North of Brooks Peninsula sediments are undeformed by folding but are truncated by faulting along the steep continental slope. The Kyuquot Uplift south of Brooks Peninsula exposes Eocene-Oligocene sediments across the shelf. Farther south Mio-Pliocene sediments unconformably overlie the uplift. Folding increases southward culminating in an area of diapirism off Nootka Sound. Elongate diapirs trend parallel or subparallel to the coastline.Tectonic features on the shelf and slope appear to be related to present and earlier configurations of nearby offshore spreading centers, plates, and transform faults. Crustal plate movements may have been responsible for the observed shelf and slope deformations.

Subsurface basement, structure, stratigraphy, and timing of regional tectonic events affecting the Guajira margin of northern Colombia

2020 ◽  
Vol 8 (4) ◽  
pp. ST69-ST105
Author(s):  
Eleine Vence ◽  
Paul Mann
Keyword(s):  
Continental Margin ◽  
Late Eocene ◽  
Seismic Facies ◽  
Tectonic Events ◽  
Regional Tectonic ◽  
Basin Formation ◽  
The Caribbean ◽  
Basement High ◽  
Marine Seismic ◽  
Sea Fan

We have combined previous data from Mesozoic-Cenozoic outcrops in the Guajira Peninsula of northern Colombia with regional gravity, bathymetric, and seismic interpretations to demonstrate the existence of a 280 km long western extension of the Great Arc of the Caribbean (GAC) along the continental margin of Colombia. Seismic data reveal an 80–100 km wide domal-shaped basement high that exhibits internal chaotic seismic facies. This elongate and domal-shaped structure extends 1800 km from the Aves Ridge in the Caribbean Sea to the study area in offshore Colombia. The western extension of the GAC in Colombia and western Venezuela is buried by 700–3000 m of continental margin sedimentary rocks as a result of the GAC colliding earlier with the Colombian margin (Cretaceous-early Paleogene collision) than its subaerially exposed eastern extension along the Leeward Antilles ridge (late Paleogene-Neogene). Our compilation of geologic information from the entire GAC reveals that GAC magmatism occurred from 128 to 74 Ma with magmatism ages progressively younger toward the east. Six upper Eocene to recent marine seismic sequences overlying the domal basement high of the GAC have been mapped by our analysis of 2400 km of seismic lines and 12 well logs. Based on subsurface mapping correlated with well-log information and onland geology in the Guajira Peninsula, these six sequences record four major deformational events: (1) late Eocene rifting in an east–west direction produced half-grabens in the northern part of the area, (2) Oligocene transtension in the southern part of the area expressed by right-lateral Oligocene strike-slip faulting and extensional basin formation, (3) early-middle Miocene transtension, and (4) late Miocene-early Pliocene Andean uplift accompanied by rapid erosion and clastic infilling of offshore basins by the Magdalena delta and deep-sea fan. The significance of this basin framework is discussed for known and inferred hydrocarbon systems.

Evolution of the Pacific Margin, Vancouver Island, and adjacent regions

1977 ◽  
Vol 14 (9) ◽  
pp. 2062-2085 ◽  
Author(s):  
J. E. Muller
Keyword(s):  
Subduction Zone ◽  
Continental Margin ◽  
Upper Jurassic ◽  
Vancouver Island ◽  
Late Eocene ◽  
Volcanic Arc ◽  
Late Mesozoic ◽  
Clastic Sediments ◽  
The Pacific ◽  
Uplift And Erosion

The tectonic–stratigraphic evolution of Vancouver Island, a part of the Insular Belt, is reviewed as it relates to the other major tectonic belts recognized in the western Cordillera of Canada and the adjacent United States. The Pacific Belt, recognized south of the international border, is also identified in the west and south of the island. Oldest rocks of the Insular Belt are a late Paleozoic volcanic arc terrane and a crystalline 'basement' that is probably pre-Devonian. A thick Upper Triassic succession of tholeiitic pillow lavas and flows, overlain by carbonate–clastic sediments, rests in part on the Paleozoic. Elsewhere the tholeiite may represent oceanic floor, perhaps formed when the Insular Belt was fragmented and rifted off the continental margin far to the south. Above it the Early Jurassic volcanic arc with related batholiths may have been aligned with a similar terrane in the Intermontane Belt before the two belts assumed parallel positions in late Mesozoic time. An Upper Jurassic – Lower Cretaceous westward thickening clastic wedge indicates uplift and erosion of the volcanic arc in late Mesozoic time. Further west the 'inner Pacific Belt' of Jura-Cretaceous elastics and chert represent slope and trench deposits that have been deformed to mélange or converted to schist. They are coeval and homologous to Franciscan and Chugach Terranes and probably mark the late Mesozoic trench and subduction zone along the continental margin. The Coast Plutonic Belt represents the related volcanic arc, and pre-Cretaceous Insular Belt rocks, unconformably overlain by Cretaceous clastic sediments, represent the arc–trench gap and fore-arc basin. Until Late Cretaceous time convergence of the Insular and Pacific Belts occurred along San Juan Fault. In early Tertiary time Eocene oceanic basalt (Outer Pacific Belt) and Jura-Cretaceous metasediments (Inner Pacific Belt) converged by under-thrusting and (or) strike–slip faulting along Leech River Fault. In Late Eocene time the trench and subduction zone shifted westward to the present core zone of the Olympic Mountains and shifted again in Miocene time to its present position.

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