Sediment dispersal and accretionary growth of the North Panama deformed belt

1995 ◽  
pp. 213-224 ◽  
Author(s):  
Donald L. Reed ◽  
Eli A. Silver
Keyword(s):  
Sediment Dispersal ◽  
The North

THE PERSISTENCE AND EFFECTS OF NON-WATER-BASED DRILLING FLUIDS ON AUSTRALIA'S NORTH WEST SHELF: PROGRESS FINDINGS FROM THREE SEABED SURVEYS

1999 ◽  
Vol 39 (1) ◽  
pp. 647 ◽  
Author(s):  
G.A. Oliver ◽  
S.J. Fisher
Keyword(s):  
Biological Effects ◽  
Drilling Fluids ◽  
Well Drilling ◽  
North West ◽  
Sediment Dispersal ◽  
Discharge Point ◽  
The North ◽  
Sediment Redistribution ◽  
Water Based ◽  
One Year

The effects and persistence of non-water-based drilling fluids discharged into the marine environment were investigated at three locations on Western Australia's North West Shelf (NWS), namely the North Rankin 4A' (NRA) drilling platform, the Wanaea–6 production well and the Lynx–la exploration well. For the multiple-well drilling operation at NRA, acute biological effects at the completion of drilling were restricted to within 400 m in the direction of the prevailing current. High total petroleum hydrocarbon (TPH) concentrations within the NRA cuttings pile persisted between 1991 and 1993. Away from the cuttings pile itself, a consistent downward trend in TPH concentrations was evident, indicating an approximate half-life of one year for surface sediments. Three years after the completion of drilling at Wanaea–6, biological effects appeared to be limited to within 100 m of the cuttings discharge point, with background concentrations of TPH and trace metals occurring near 1,200 m in the direction of the prevailing current. Sediment hydrocarbon concentrations greater than 1 mg/kg were found to be restricted to within 200 m of the cuttings discharge point. Dramatic reductions in TPH and barium concentrations occurred in the 12-month period between the completion of drilling and the follow- up survey at Lynx–la. The reductions are attributed to sediment dispersal mechanisms which appear to play a major role in reducing sediment TPH and trace metal concentrations in mid-shelf water depths (70–80 m) on the NWS. The installation and presence of subsea production facilities may result in sediment redistribution and changed dispersal mechanisms, complicating the interpretation of the presence of contaminants within sediments.

scholarly journals Detrital zircon record of magmatism and sediment dispersal across the North American Cordilleran arc system (28–48°N)

2021 ◽  
pp. 103734
Author(s):  
Theresa M. Schwartz ◽  
Kathleen D. Surpless ◽  
Joseph P. Colgan ◽  
Samuel A. Johnstone ◽  
Christopher S. Holm-Denoma
Keyword(s):  
North American ◽  
Detrital Zircon ◽  
Sediment Dispersal ◽  
The North

scholarly journals Early Pennsylvanian sediment routing to the Ouachita Basin (southeastern United States) and barriers to transcontinental sediment transport sourced from the Appalachian orogen based on detrital zircon U-Pb and Hf analysis

Geosphere ◽  
2021 ◽  
Author(s):  
Isaac J. Allred ◽  
Michael D. Blum
Keyword(s):  
United States ◽  
Detrital Zircon ◽  
Eastern United States ◽  
Ouachita Mountains ◽  
Sediment Dispersal ◽  
Continental Scale ◽  
The North ◽  
Sediment Routing ◽  
Proximal Site ◽  
Central United States

Carboniferous sediment dispersal from the Appalachian orogenic system (eastern United States) has become a topic of widespread interest. However, the actual pathways for continental-scale, east-to-west sediment transfer have not been documented. This study presents detrital zircon (DZ) U-Pb ages and Hf isotopic values from the Lower Pennsylvanian (Morrowan) Jackfork Group and Johns Valley Shale of the synorogenic Ouachita deepwater basin of Arkansas to document provenance and delineate the likely sediment-routing systems within the broader context of sediment dispersal across Laurentia. Twelve (12) DZ U-Pb age distributions are interpreted to indicate that sediments were derived from the Appalachians to the east and northeast, as well as the midcontinent region to the north. All samples display prominent ca. 500– 400 Ma, 1250–950 Ma, 1550–1300 Ma, and 1800–1600 Ma grains, consistent with ultimate derivation from the Appalachian, Grenville, Midcontinent, and Yavapai-Mazatzal provinces. DZ Hf values obtained from the Ouachita Basin are similar to published Hf values from Pennsylvanian samples in the Appalachian and Illinois Basins. Age distributions are generally consistent for seven samples collected from the Jackfork Group and Johns Valley Shale in the southern Ouachita Mountains through ~2400 m of stratigraphic section and are interpreted to indicate little change in provenance during the Morrowan in this part of the system. However, samples from the most northern and most source-proximal site in Little Rock, Arkansas, exhibit modest percentages of Appalachian ages and elevated contributions of Yavapai-Mazatzal ages when compared with samples collected farther to the south and west. We interpret differences between DZ signatures to indicate distinct sediment-routing pathways to the Ouachita Basin. We infer the strong Appalachian and Grenville signals to represent an axial system flowing through the Appalachian foredeep, whereas the more diverse signals represent a confluence of rivers from the northeast through the backbulge of southern Illinois and western Kentucky and from the north across the Arkoma shelf. Collectively, the Ouachita Basin represents a terminal sink for sediments derived from much of the eastern and central United States.

Silurian collision and sediment dispersal patterns in southern Britain

1990 ◽  
Vol 127 (6) ◽  
pp. 527-542 ◽  
Author(s):  
N. J. Soper ◽  
N. H. Woodcock
Keyword(s):  
Large Volume ◽  
High Volume ◽  
Dispersal Patterns ◽  
Polar Wander ◽  
Sediment Dispersal ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Anticlockwise Rotation ◽  
Laurentian Margin ◽  
First Time

AbstractThe evidence is reviewed for the timing of collision between the microcontinent of Eastern Avalonia (southern Britain and adjacent areas) and the Laurentian continent. Recent palaeomagnetic results placing Eastern Avalonia in a high (50°) southern latitude in mid Ordovician time are now consistent with faunal evidence for the first time. The resulting apparent polar wander path is evaluated and suggests that Eastern Avalonia detached itself from a southern peri-Gondwanan latitude in the early Ordovician, moved northwards, and approached Laurentia by the late Ordovician. Its western corner probably impinged on Laurentia in the early Silurian and it docked against the Laurentian margin during Silurian and early Devonian time with a component of anticlockwise rotation.This kinematic history is supported by a compilation of sediment dispersal patterns on Eastern Avalonia. A low-volume Ordovician and earliest Silurian supply from within the microcontinent was overwhelmed in late Llandovery time by a large volume of southwest-derived turbidites, probably from the uplifting impact zone to the west. This source was later augmented by a high-volume clastic supply to the north margin of the microcontinent. Eastward migration of this source through Wenlock and Ludlow time reflects the progressive anticlockwise docking of Eastern Avalonia against the Laurentian margin. The earliest sign of a large-volume supply from Baltica is in the late Wenlock, arguing against any earlier hard collision.

scholarly journals Sedimentation of the Kimmeridge Clay Formation in the Cleveland Basin (Yorkshire, UK)

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 977
Author(s):  
Elizabeth Atar ◽  
Andrew C. Aplin ◽  
Violaine Lamoureux-Var ◽  
Christian März ◽  
Thomas Wagner
Keyword(s):  
Environmental Conditions ◽  
Late Jurassic ◽  
Geochemical Data ◽  
Variable Environment ◽  
Thin Sections ◽  
Sediment Dispersal ◽  
The North ◽  
Depositional Processes ◽  
Petrographic Analyses ◽  
Clay Formation

Fine-grained sedimentary successions contain the most detailed record of past environmental conditions. High-resolution analyses of these successions yield important insights into sedimentary composition and depositional processes and are, therefore, required to contextualise and interpret geochemical data which are commonly used as palaeoclimate proxies. The Kimmeridge Clay Formation (KCF) is a 500 m-thick mudstone succession deposited throughout the North Sea in the Late Jurassic and records environmental conditions through this time. Here, we present petrographic analyses (on 36 thin sections) on a 50 m section of a KCF core from the Cleveland Basin (Yorkshire, UK) to investigate controls on sedimentation in this region during the Tithonian, Late Jurassic. Facies descriptions demonstrate that deposition took place in a hydrodynamically variable environment in which the sediment origins, sediment dispersal mechanisms, and redox conditions fluctuated on the scale of thousands of years. Petrographic analyses show that the sediment comprises marine (algal macerals, calcareous fossils), detrital (quartz, clay, feldspar), and diagenetic (dolomite and authigenic kaolinite) components and that several sediment dispersal mechanisms influenced deposition and facilitated both the supply and preservation of terrestrial and marine organic material. This work provides a framework for the interpretation of geochemical palaeoclimate proxies and reinforces the importance of looking at the rock when interpreting whole-rock geochemical data.

Sediment routing evolution in the North Alpine Foreland Basin, Austria: interplay of transverse and longitudinal sediment dispersal

2017 ◽  
Vol 30 (3) ◽  
pp. 426-447 ◽  
Author(s):  
Glenn R. Sharman ◽  
Stephen M. Hubbard ◽  
Jacob A. Covault ◽  
Ralph Hinsch ◽  
Hans-Gert Linzer ◽  
...  
Keyword(s):  
Foreland Basin ◽  
Sediment Dispersal ◽  
The North ◽  
Sediment Routing ◽  
North Alpine Foreland Basin ◽  
Alpine Foreland ◽  
Alpine Foreland Basin

scholarly journals Palinspastic restoration of an exhumed deepwater system: A workflow to improve paleogeographic reconstructions

2015 ◽  
Vol 3 (4) ◽  
pp. SAA71-SAA87 ◽  
Author(s):  
Allan L. Spikings ◽  
David M. Hodgson ◽  
Douglas A. Paton ◽  
Yvonne T. Spychala
Keyword(s):  
Cross Sections ◽  
Regional Scale ◽  
Three Dimensional ◽  
Dispersal Patterns ◽  
Lower Paleozoic ◽  
Sediment Dispersal ◽  
Karoo Basin ◽  
The North ◽  
Thrust Tectonics ◽  
Palinspastic Restoration

The Permian Laingsburg depocenter, Karoo Basin, South Africa, is the focus of sedimentological and stratigraphic research as an exhumed analog for offshore hydrocarbon reservoirs in deepwater basins. Thin-skinned thrust tectonics during the Permo-Triassic Cape Orogeny result in postdepositional deformation of the Permian basin fill. Regional-scale cross sections reveal two structural domains: a southern domain in the Laingsburg depocenter comprising 8–11-km wavelength north-verging fault-propagation folding, driven by buried low-angle ([Formula: see text]) reverse faults that coalesce at depth as part of a megadetachment below the Lower Paleozoic Cape Supergroup; and a northern domain to the north of the Laingsburg depocenter of short-wavelength, low-amplitude, asymmetrical folding facilitated by a detachment within the Permian Ecca Group. Five detailed structural cross sections permit the palinspastic restoration, and a calculation of the amount of shortening, across a [Formula: see text] area in the Laingsburg depocenter. Average shortening across the study area is −16.9% (5.8 km), and it decreases south to north. Shortening estimates from the Upper Ecca Group increase from 4.3 km near Matjiesfontein in the west to 10.4 km near Prince Albert in the east. Three-dimensional restorations of stratigraphic surfaces are consistent with these figures (−17%), and they allow paleogeographic and isopach thickness maps to be resorted to their configuration at the time of deposition. Structural restoration can be routinely used in outcrop studies to improve the accuracy of dimensions (e.g., volumetrics) and reconstructions (e.g., sediment dispersal patterns) derived from ancient sedimentary systems. The workflow presented here will add value to exhumed basin analogs by presenting prekinematic configurations at the frontal margins of fold-thrust belts.

Investor-State Dispute Settlement under NAFTA Chapter 11: The Shape of Things to Come?

1998 ◽  
Vol 35 ◽  
pp. 263-290
Author(s):  
J. Anthony VanDuzer
Keyword(s):  
Free Trade Agreement ◽  
Dispute Settlement ◽  
Trade Agreement ◽  
Minimum Standards ◽  
The North ◽  
State Behaviour ◽  
Nafta Chapter 11 ◽  
To Come ◽  
The Right

SummaryRecently, there has been a proliferation of international agreements imposing minimum standards on states in respect of their treatment of foreign investors and allowing investors to initiate dispute settlement proceedings where a state violates these standards. Of greatest significance to Canada is Chapter 11 of the North American Free Trade Agreement, which provides both standards for state behaviour and the right to initiate binding arbitration. Since 1996, four cases have been brought under Chapter 11. This note describes the Chapter 11 process and suggests some of the issues that may arise as it is increasingly resorted to by investors.

Long-term Cyclic Variations of Prominences, Green and Red Coronae over Solar Cycles

2000 ◽  
Vol 179 ◽  
pp. 201-204
Author(s):  
Vojtech Rušin ◽  
Milan Minarovjech ◽  
Milan Rybanský
Keyword(s):  
Emission Lines ◽  
High Latitudes ◽  
Green Line ◽  
Solar Cycles ◽  
The South ◽  
Coronal Emission ◽  
Local Maxima ◽  
The North ◽  
Cyclic Variations

AbstractLong-term cyclic variations in the distribution of prominences and intensities of green (530.3 nm) and red (637.4 nm) coronal emission lines over solar cycles 18–23 are presented. Polar prominence branches will reach the poles at different epochs in cycle 23: the north branch at the beginning in 2002 and the south branch a year later (2003), respectively. The local maxima of intensities in the green line show both poleward- and equatorward-migrating branches. The poleward branches will reach the poles around cycle maxima like prominences, while the equatorward branches show a duration of 18 years and will end in cycle minima (2007). The red corona shows mostly equatorward branches. The possibility that these branches begin to develop at high latitudes in the preceding cycles cannot be excluded.

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