scholarly journals Mantle plumes and sequence stratigraphy; Late Maastrichtian- Early Paleocene of West Greenland

2001 ◽  
Vol 48 ◽  
pp. 189-207
Author(s):  
Gregers Dam
Keyword(s):  
Rapid Development ◽  
Flood Basalt ◽  
Mantle Plumes ◽  
Sea Level Changes ◽  
West Greenland ◽  
Sedimentary Sequences ◽  
The North ◽  
Early Paleocene ◽  
History Of ◽  
Sequence Boundaries

The sedimentary history of the upper Maastrichtian–Paleocene succession underneath the extensive Paleocene flood basalts in central West Greenland supports models for the generation of flood basalt provinces in response to rising, hot mantle plumes. The rise of the North Atlantic mantle plume was associated with deposition of at least three sedimentary sequences; each associated with incision of submarine canyons and valleys. Relative sea-level changes were caused by plumerelated tectonics and generation of sequence boundaries was in general associated with catastrophic sedimentation and very rapid development of sequences. As such the late Maastrichtian–early Paleocene sequences record a spectacular and significant but rare geological event.

Tremadocian (Lower Ordovician) sea-level changes and biotas on the Avalon microcontinent

2011 ◽  
Vol 85 (4) ◽  
pp. 678-694 ◽  
Author(s):  
ED Landing ◽  
Richard A. Fortey
Keyword(s):  
Sea Level ◽  
Sea Level Changes ◽  
Low Oxygen ◽  
Cape Breton Island ◽  
Lower Upper ◽  
The North ◽  
Cape Breton ◽  
Lower Ordovician ◽  
Bottom Waters ◽  
History Of

The Chesley Drive Group, an Upper Cambrian-Lower Ordovician mudstone-dominated unit, is part of the Ediacaran–Ordovician cover sequence on the North American part of the Avalon microcontinent. The upper Chesley Drive Group on McLeod Brook, Cape Breton Island (previously “McLeod Brook Formation”), has two lithofacies-specific Tremadocian biotas. An older low-diversity benthic assemblage (shallow burrowers, Bathysiphon, phosphatic brachiopods, asaphid trilobites) is in lower upper Tremadocian green-gray mudstone. This wave-influenced, slightly dysoxic facies has Bathysiphon–brachiopod shell lags in ripple troughs. The upper fauna (ca. 483 +/- 1 Ma) is in dysoxic-anoxic (d-a), unburrowed, dark gray-black, upper upper (but not uppermost) Tremadocian mudstone with a “mass kill” of the olenid Peltocare rotundifrons (Matthew)—a provincial trilobite in Avalonian North America that likely tolerated low oxygen bottom waters. Scandodus avalonensis Landing n. sp. and Lagenochitina aff. conifundus (Poumot), probable nektic elements and the first upper Tremadocian conodont and chitinozoan reported from Avalon, occur in diagenetic calcareous nodules in the dark gray-black mudstone. An upper Tremadocian transition from lower greenish to upper black mudstone is not exposed on McLeod Brook, but is comparable to a coeval green-black mudstone transition in Avalonian England. The successions suggest that late late Tremadocian (probable Baltic Hunnebergian Age) sea level was higher in Avalon than is suggested from successions on other paleocontinents. The Tremadocian sea-level history of Avalon was a shoaling-deepening-shoaling sequence from d-a black mudstone (lower Tremadocian), to dysoxic green mudstone (lower upper Tremadocian), and back to black mudstone (upper upper Tremadocian).Scandodus Lindström is emended, with the early species S. avalonensis Landing n. sp. assigned to the emended Family Protopanderodontidae. Triangulodus Van Wamel is considered a junior synonym of Scandodus. Peltocare rotundifrons is emended on the basis of complete specimens.

ARCHAEAN SEDIMENTARY ROCKS OF NORTH SPIRIT LAKE AREA, NORTHWESTERN ONTARIO

1965 ◽  
Vol 2 (6) ◽  
pp. 622-647 ◽  
Author(s):  
J. A. Donaldson ◽  
G. D. Jackson
Keyword(s):  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Sole Source ◽  
Lake Area ◽  
Red Lake ◽  
Sedimentary Sequences ◽  
The North ◽  
Northwestern Ontario ◽  
History Of ◽  
Granitoid Rocks

Archaean sedimentary rocks of the North Spirit Lake area show little evidence of having been derived predominantly from associated Archaean volcanic rocks. Instead, compositions of the sediments reflect significant sedimentary and (or) granitoid provenance. A remarkably high content of clastic quartz in thick units of sandstone and conglomerate suggests either reworking of older quartzose sediments, or reduction of the labile constituents in quartz-rich granitoid rocks through prolonged weathering and rigorous transport. Observations for other sedimentary sequences in the region between Red Lake and Lansdowne House suggest that the North Spirit sediments are not unique in the Superior Province. Quartzose sandstones commonly are regarded as atypical of the Archaean, but such rocks arc abundant in northwestern Ontario. Frameworks of many Archaean greywackes actually are richer in quartz than typical greywackes from numerous Proterozoic and Phanerozoic sequences.The concept of rapidly rising volcanic arcs as the sole source of Archaean sedimentary detritus is rejected for the North Spirit area. The volcanies, rather than representing relicts of protocontinents, probably record events removed from initial volcanism in the history of the earth by one or more orogenic cycles. Major unconformities may therefore exist not only between sedimentary and volcanic units, but also between these units and older granitoid rocks.

scholarly journals Holocene sea-level change and estuary infill in North West Nelson, central New Zealand

The Holocene ◽  
2021 ◽  
pp. 095968362110604
Author(s):  
David M Kennedy ◽  
Beth V Risdon ◽  
Josephine LD Woods
Keyword(s):  
New Zealand ◽  
Sea Level ◽  
Central Basin ◽  
Marine Transgression ◽  
The Holocene ◽  
North West ◽  
Sedimentary Sequences ◽  
The North ◽  
History Of ◽  
Holocene Sea Level

The sedimentary sequences found within estuaries in the north west Nelson region of central New Zealand are investigated in order to quantify the timing of the end of the Post Glacial Marine Transgression. This region has been identified as being relatively stable in terms of vertical tectonic movement during the Holocene, but is yet to yield any reconstructions of eustatic sea level. In this study, we investigate the Holocene infill of a barrier estuary (Parapara Inlet) through sedimentological analysis and radiocarbon dating of 18 vibracores up to 4.2 m in length. It is found that the estuary infilled through a combination of lateral flood tide and fluvial delta progradation as well as vertical central basin infill. The central basin infilled at a consistent rate of 0.4 mm/year in both the mid (7.0–6.0 ka) and late-Holocene (2.5–1.5 ka). By the time of early human (Maori) settlement (c. 1 ka), the estuary surface was at low intertidal elevations with sediment being transported from the fluvial to tidal delta. A discernible change in sedimentation rates could not be associated with Maori settlement; however, infill rates increased to at least 12.5 mm/year in the past 150 years due hydraulic sluicing associated with mining. The sedimentary history of Parapara Inlet is compared to nearby Whanganui Inlet, d’Urville Island and Nelson to establish the character of regional Holocene sea level movement. It is found that relative sea level reached modern elevations between 8 and 7 ka in the region. The similarity between sea level curves for the end of the post glacial marine transgression (PMT) to other tectonically stable sites in northern New Zealand suggests that this curve can now be considered a true eustatic signal for the New Zealand archipelago.

scholarly journals Depositional environment of the Branch Sandstone and correlative sequences: Late Cretaceous changes in relative sea level in the East Coast Basin of New Zealand

2021 ◽  
Author(s):  
◽  
Lisa McCarthy
Keyword(s):  
Sea Level ◽  
East Coast ◽  
Depositional Environments ◽  
Passive Margin ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Sea Level Fluctuations ◽  
The North ◽  
Tasman Sea ◽  
History Of

<p>The Branch Sandstone is located within an overall transgressive, marine sedimentary succession in Marlborough, on the East Coast of New Zealand’s South Island. It has previously been interpreted as an anomalous sedimentary unit that was inferred to indicate abrupt and dramatic shallowing. The development of a presumed short-lived regressive deposit was thought to reflect a change in relative sea level, which had significant implications for the geological history of the Marlborough region, and regionally for the East Coast Basin.  The distribution and lithology of Branch Sandstone is described in detail from outcrop studies at Branch Stream, and through the compilation of existing regional data. Two approximately correlative sections from the East Coast of the North Island (Tangaruhe Stream and Angora Stream) are also examined to provide regional context. Depositional environments were interpreted using sedimentology and palynology, and age control was developed from dinoflagellate biostratigraphy. Data derived from these methods were combined with the work of previous authors to establish depositional models for each section which were then interpreted in the context of relative sea level fluctuations.  At Branch Stream, Branch Sandstone is interpreted as a shelfal marine sandstone, that disconformably overlies Herring Formation. The Branch Sandstone is interpreted as a more distal deposit than uppermost Herring Formation, whilst the disconformity is suggested to have developed during a fall in relative sea level. At Branch Stream, higher frequency tectonic or eustatic sea-level changes can therefore be distinguished within a passive margin sedimentary sequence, where sedimentation broadly reflects subsidence following rifting of the Tasman Sea. Development of a long-lived disconformity at Tangaruhe Stream and deposition of sediment gravity flow deposits at Angora Stream occurred at similar times to the fall in relative sea level documented at the top of the Herring Formation at Branch Stream. These features may reflect a basin-wide relative sea-level event, that coincides with global records of eustatic sea level fall.</p>

Evolution des reseaux hydrographiques au contact Cevennes-Grands Causses meridionaux; consequences sur l'evaluation de la surrection tectonique

2001 ◽  
Vol 172 (5) ◽  
pp. 549-562 ◽  
Author(s):  
Hubert Camus
Keyword(s):  
Network Evolution ◽  
River Network ◽  
Driving Mechanism ◽  
Sea Level Changes ◽  
Massif Central ◽  
The North ◽  
Vertical Incision ◽  
History Of ◽  
Surrounding Areas ◽  
The Hill

Abstract The Mediterranean catchment of the Cevennes (S. France) presents deep incision of the river network (fig. 1 and 2). Combined geomorphology and analyses of the residual sedimentary formations allows to reconstruct a complex history of river network evolution, including capture of tributaries of the Herault River (fig. 1, 2 and 3). The history of uplift of the upstream drainage area could be estimated from the provenance studies of the fluvial and karstic deposits, however river incision is also controlled sea-level changes and differential erosion, which makes reconstruction more complex. Allochthonous clasts types: Analyses of allochthonous deposits on the Grands Causses surface reveals different origin for sediments from the hill top and the Airoles valley (fig. 4 b), which was previously unrecognised. Facies 1 is found on the highest points of the Grands Causses surface (well sorted rounded quartz pebbles in red shale matrix) it corresponds to a weathered residual sediments (dismantling of an ancient cover). Facies 2 is found on the slope of the Airoles Valley (fig. 7). It consists of alluvial crystalline poorly sorted clasts with outsized clasts (up to 50 cm) of quartz-vein, schists in a matrix of shales and sand (weathered granite). Between the hill tops and the Airoles Valley, karstic network presents a sediment fill with clasts reworked from facies 1 and facies 2 (fig. 6). Airoles valley model; an example of diachronic formation of drainage network: The Airoles dry valley stretches on the Grands Causses from the north (700 m) to the south into the present thalweg line of the Vis canyon (500 m) (fig. 1b & 3). Crystalline deposits witness an ancient catchment in the Cevennes. Presently, the catchment in the crystalline basement is disconnected and captured by the Arre River flowing eastwards (fig. 3 & 4a). The profile of the Airoles abandoned valley connects with the present Vis Canyon, therefore, at the time of capture, incision of the Vis canyon had reached its present altitude (fig. 4a). The geomorphologic evolution of this area took place in three stages (fig. 8). 1) The Grands Causses acted as piedmont for the crystalline highlands of the Massif Central (fig. 8A). A latter karstic evolution (tropical climate) allowed the weathered residual sediments (facies 1) (fig. 8A). 2) Incision of the Vis karstic canyon implies that the Herault incision and terraces (facies 2) (fig. 8B) of the Airoles valley occurred during this stage. 3) The Arre valley head propagates westward by regressive erosion and finally captured the Airoles river crystalline catchment (fig. 8C). Consequence for the Cevennes uplift and hydrographic network development: Although the values of present vertical incision in the Vis canyon and in the Arre valley are similar, but they achieved at different time. In addition, the narrow and deep canyon of the Vis is due to vertical incision from the karstic surface of the Grands Causses, whereas the Arre wide valley results from (a younger) lateral slopes retreat from a low Herault base-level. The Vis karstic canyon developed in a similar way to the major karstic canyons of both Mediterranean and Atlantic catchment (i.e. Tarn). This rules out a Messinian Mediterranean desiccation as incision driving mechanism and suggests tectonic uplift of the Cevennes and surrounding areas. The Tarn being already incised by 13 My [Ambert, 1990], it implies a Miocene age for the incision. Conclusion: The amplitude of the vertical incision cannot therefore be used in a simple way to interpret the uplift history of the basement. Consequently, geomorphologic analysis appears to be a prerequisite to distinguish the part played by each factor, and to select the site of uplift measurement.

scholarly journals Mainland versus Island Adaptation: Paleobiogeography of Sunda Shelf Primates Revisited

2020 ◽  
Author(s):  
Halmi Insani ◽  
Masanaru Takai
Keyword(s):  
Homo Erectus ◽  
Sea Level Changes ◽  
Sunda Shelf ◽  
The North ◽  
Biogeographical Distribution ◽  
Paleoclimatic Changes ◽  
Wide Range ◽  
History Of ◽  
Dispersal Events ◽  
Human Primate

Southeast Asian primates appear to be one of the most successful mammals in the dynamic paleoclimatic changes since at least 1 mya. Human and non-human primates reflect the complex history of a wide range of ecological and geographic variation, which presents to be the source of different systematics and biogeographic models. The past combinative effects of geographic factors (latitude, bathymetric barrier, and duration of island isolation), periodic sea level changes, and the contribution of human and/or non-human primate interaction are crucial subjects in studying the north-to-south, which is from continental to archipelago of Sunda Shelf, dispersal events and phylogeographic analysis of human and non-human primates. Cranial size and shape difference between Homo erectus in mainland and island displays peculiarity on the effect of insularity. Data analyses on cranial landmarks of three non-human primate genera provide more clear resolution to reconstruct the complete scenario, whereby insular primates are dispersed and adapted to their present biogeographical distribution.

scholarly journals North Atlantic marine biogenic silica accumulation through the early-to-mid Paleogene: implications for ocean circulation and silicate weathering feedback

2021 ◽  
Author(s):  
Jakub Witkowski ◽  
Karolina Bryłka ◽  
Steven M. Bohaty ◽  
Elżbieta Mydłowska ◽  
Donald E. Penman ◽  
...  
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Biogenic Silica ◽  
Middle Eocene ◽  
Nutrient Supply ◽  
Silicate Weathering ◽  
The North ◽  
Early Paleocene ◽  
History Of ◽  
The North Atlantic

Abstract. The Paleogene history of biogenic opal accumulation in the North Atlantic provides insight into both the evolution of deep-water circulation in the Atlantic basin, and weathering responses to major climate shifts. However, existing records are compromised by low temporal resolution and/or stratigraphic discontinuities. In order to address this problem, we present a multi-site, high-resolution record of biogenic silica (bioSiO2) accumulation from Blake Nose (ODP Leg 171B, western North Atlantic) spanning the early Paleocene through late Eocene time interval (~65‒34 Ma). This record represents the longest single-locality history of marine bioSiO2 burial compiled to date and offers a unique perspective into changes in bioSiO2 fluxes through the early-to-mid Paleogene extreme greenhouse interval and subsequent period of long-term cooling. Blake Nose bioSiO2 fluxes display prominent fluctuations that we attribute to variations in sub-thermocline nutrient supply via cyclonic eddies associated with the Gulf Stream. Whereas few constraints are available on the bioSiO2 flux pulses peaking in the early Paleocene and early Eocene, a middle Eocene interval of elevated bioSiO2 flux between ~46 and 42 Ma is proposed to reflect nutrient enrichment due to invigorated overturning circulation following an early onset of Northern Component Water export from the Norwegian-Greenland Sea at ~49 Ma. Comparison of our North Atlantic record against published Pacific bioSiO2 flux records indicates a diminished nutrient supply to the Atlantic between ~42 and 38 Ma, interpreted as a response to weakening of the overturning circulation. Subsequently, a deep-water circulation regime favoring limited bioSiO2 burial in Atlantic and enhanced bioSiO2 burial in the Pacific was established after ~38 Ma, likely in association with a further invigoration of deep-water export from the North Atlantic. We also observe that Blake Nose bioSiO2 fluxes through the middle Eocene cooling interval (~48 to 34 Ma) are consistently higher than background fluxes throughout the late Paleocene‒early Eocene interval of intense greenhouse warmth. This observation is consistent with a temporally variable rather than constant silicate weathering feedback strength model for the Paleogene, which would instead predict that marine bioSiO2 burial should peak during periods of extreme warming.

The west Greenland cod fishery

Polar Record ◽  
1966 ◽  
Vol 13 (82) ◽  
pp. 23-28
Author(s):  
D. J. Garrod
Keyword(s):  
North Atlantic ◽  
General Pattern ◽  
The West ◽  
West Greenland ◽  
Fishery Resources ◽  
The North ◽  
History Of ◽  
The North Atlantic ◽  
Post War

The conception of the sea as an unlimited reservoir of fish is now outdated. The post-war history of the fishery resources of the north Atlantic has shown that stocks can be depleted to a level where the catching rates are no longer an economical proposition, and the general pattern of expansion has been to move farther afield to grounds where the catches are sufficiently improved to offset the greater steaming time, and hence running costs, involved.

The sea as a dynamic and hybrid landscape

2011 ◽  
Author(s):  
Robert Van de Noort
Keyword(s):  
North Sea ◽  
Late Glacial ◽  
Sea Level Changes ◽  
The North ◽  
History Of Research ◽  
Research Activities ◽  
Dynamic Landscape ◽  
History Of ◽  
The North Sea ◽  
The 19Th Century

Since the last glacial maximum, some 22,000 years ago, the North Sea basin has undergone many transformational changes. Largely covered by ice at the beginning of the period, it became successively an arctic-like tundra, a ‘park-like’ landscape of extended grassland with shrubs and trees, a tundra again, and a plain with light woodland cover that was submerged eventually by the expanding North Sea (Coles 1998: 69–75). As the North Sea rose, over the last 5,000 years, to within a few metres of its current level, the interior of the sea did not alter significantly apart from changes in tidal patterns and depth. But on the periphery of the North Sea basin, the slighter sea-level changes added to the effects of marine and alluvial sedimentation and erosion and produced, regionally, periods of marine transgression—when the influence of the sea moved landwards—and marine regression, resulting in the opposite effect. The North Sea, throughout its history, has been the dynamic landscape par excellence. The history of research into the North Sea basin goes back to the 19th century, and will be discussed further below, but it was Bryony Coles’ article ‘Doggerland: a speculative survey’ (1998), which first raised the profile of the Late-glacial and early Holocene archaeology of the North Sea and inspired many of the current research activities, especially those relating to the southern North Sea basin. The renewed interest in the Mesolithic and Neolithic archaeology of the North Sea has made some significant advances, and holds the promise of even greater returns once the high-resolution reconstructions of the North Sea Plain are integrated with the archaeological finds. A series of publications has recently presented new archaeological sites. New finds from trawler fishing along the various banks in the North Sea, and from the margins (e.g. Flemming 2004; Waddington and Pedersen 2007), as well as the use of SCUBA technology (e.g. in Fisher 1995), will be discussed below. This chapter offers brief overviews of the history of North Sea research, the creation of the North Sea, and the archaeological evidence of human activity in the period from about 10,000 to 2000 cal bc.

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