Tectonic Controls on Cenozoic Sedimentation in the North Island New Zealand

1988 ◽  
Vol 6 (2) ◽  
pp. 104-117
Author(s):  
K.B. Spörli
Keyword(s):  
East Coast ◽  
Fault System ◽  
Clockwise Rotation ◽  
The North ◽  
Alpine Fault ◽  
The Pacific ◽  
Pacific Side ◽  
Forearc Basins ◽  
Subduction System ◽  
Coast Region

Cenozoic deformation of the North Island was dominated by the “closure” of the Challenger Rift and the establishment of the presently active subduction system. The initiation of subduction-related volcanic chains and their subsequent migration influenced the source of clastic material deposited in the Neogene basins. Uplift patterns, shoreline and drainage configurations were governed by complex 3-D distortion of the transition between the Alpine Fault system in the south and the Hikurangi through subduction system in the north. Along the Pacific side of the island, in Northland, some “piggy back” basins were formed on allochthonous pockets of sediments involved in obduction of ocean floor rocks onto the North island. Clockwise rotation on the east coast region and alternate coupling and decoupling across the subduction thrust created short-lived forearc basins. Axial ranges, and derivation of gravels from them are younger than 1 m y B.P. A very young, still active cross structure due to oblique subduction led to the formation of South Taranaki Bight, caused differences in the width of the axial ranges along their length and may be the reason for the peculiar coastal indentation of Hawke Bay.

The discovery of a new sedimentary basin: offshore Raukumara, East Coast, North Island, New Zealand

2008 ◽  
Vol 48 (1) ◽  
pp. 53 ◽  
Author(s):  
Chris Uruski ◽  
Callum Kennedy ◽  
Rupert Sutherland ◽  
Vaughan Stagpoole ◽  
Stuart Henrys
Keyword(s):  
New Zealand ◽  
Oil And Gas ◽  
East Coast ◽  
Plate Boundary ◽  
Source Rocks ◽  
Fault System ◽  
Northern Coast ◽  
The South ◽  
Petroleum Potential ◽  
The North

The East Coast of North Island, New Zealand, is the site of subduction of the Pacific below the Australian plate, and, consequently, much of the basin is highly deformed. An exception is the Raukumara Sub-basin, which forms the northern end of the East Coast Basin and is relatively undeformed. It occupies a marine plain that extends to the north-northeast from the northern coast of the Raukumara Peninsula, reaching water depths of about 3,000 m, although much of the sub-basin lies within the 2,000 m isobath. The sub-basin is about 100 km across and has a roughly triangular plan, bounded by an east-west fault system in the south. It extends about 300 km to the northeast and is bounded to the east by the East Cape subduction ridge and to the west by the volcanic Kermadec Ridge. The northern seismic lines reveal a thickness of around 8 km increasing to 12–13 km in the south. Its stratigraphy consists of a fairly uniformly bedded basal section and an upper, more variable unit separated by a wedge of chaotically bedded material. In the absence of direct evidence from wells and samples, analogies are drawn with onshore geology, where older marine Cretaceous and Paleogene units are separated from a Neogene succession by an allochthonous series of thrust slices emplaced around the time of initiation of the modern plate boundary. The Raukumara Sub-basin is not easily classified. Its location is apparently that of a fore-arc basin along an ocean-to-ocean collision zone, although its sedimentary fill must have been derived chiefly from erosion of the New Zealand land mass. Its relative lack of deformation introduces questions about basin formation and petroleum potential. Although no commercial discoveries have been made in the East Coast Basin, known source rocks are of marine origin and are commonly oil prone, so there is good potential for oil as well as gas in the basin. New seismic data confirm the extent of the sub-basin and its considerable sedimentary thickness. The presence of potential trapping structures and direct hydrocarbon indicators suggest that the Raukumara Sub-basin may contain large volumes of oil and gas.

scholarly journals Observed Changes in Cyclone Activity in Canada and Their Relationships to Major Circulation Regimes

2006 ◽  
Vol 19 (6) ◽  
pp. 896-915 ◽  
Author(s):  
Xiaolan L. Wang ◽  
H. Wan ◽  
Val R. Swail
Keyword(s):  
Regression Analysis ◽  
Great Lakes ◽  
East Coast ◽  
Southern Oscillation ◽  
Linear Regression Analysis ◽  
Cyclone Activity ◽  
The North ◽  
The Pacific ◽  
Central Canada ◽  
The North Atlantic Oscillation

Abstract This study assessed the climate and trend of cyclone activity in Canada using mainly the occurrence frequency of cyclone deepening events and deepening rates, which were derived from hourly mean sea level pressure data observed at 83 Canadian stations for up to 50 years (1953–2002). Trends in the frequency of cyclone activity were estimated by logistic regression analysis, and trends of seasonal extreme cyclone intensity, by linear regression analysis. The results of trend analysis show that, among the four seasons, winter cyclone activity has shown the most significant trends. It has become significantly more frequent, more durable, and stronger in the lower Canadian Arctic, but less frequent and weaker in the south, especially along the southeast and southwest coasts. Winter cyclone deepening rates have increased in the zone around 60°N but decreased in the Great Lakes area and southern Prairies–British Columbia. However, extreme winter cyclone activity seems to have experienced a weaker increase in northwest-central Canada but a stronger decline in the Great Lakes area and in southern Prairies. The results also show more frequent summer cyclone activity with slower deepening rates on the east coast, as well as less frequent cyclone activity with faster deepening rates in the Great Lakes area in autumn. Cyclone activity in Canada was found to be closely related to the North Atlantic Oscillation (NAO), the Pacific Decadal Oscillation (PDO), and El Niño–Southern Oscillation (ENSO). Overall, cyclone activity in Canada is most closely related to the NAO. The simultaneous NAO index explains about 44% (41%) of the winter (autumn) cyclone activity variance in the east coast, 31% of winter cyclone activity variance in the 60°–70°N zone, and 17% of autumn cyclone activity variance in the Great Lakes area. Also, in several regions (e.g., the east coast, the southwest, and the 60°–70°N zone) up to 15% of the seasonal cyclone activity variance can be explained by the NAO/PDO/ENSO index one–three seasons earlier, which is useful for seasonal forecasting.

Structural Characteristics and Mechanism of the Horsetail Structure in China Offshore Basins: Case Studies from Liaodong Bay Area, Bohai Bay Basin and Weixinan Area, Beibuwan Basin

2020 ◽  
Author(s):  
Jie Zhang ◽  
Zhiping Wu ◽  
Yanjun Cheng
Keyword(s):  
Structural Characteristics ◽  
Strike Slip ◽  
Pacific Plate ◽  
Strike Slip Fault ◽  
Bohai Bay ◽  
Liaodong Bay ◽  
Clockwise Rotation ◽  
Bay Area ◽  
The North ◽  
The Pacific

<p>The horsetail structure, also named brush structure, generally refers to a sets of secondary faults converged to the primary fault on the plane. Based on 2-D and 3-D seismic data, the structural characteristics, evolution and mechanism of the horsetail structure of Liaodong Bay area in Bohai Bay Basin and Weixinan area in Beibuwan Basin are analyzed. In the Liaodong Bay area, the primary fault of the horsetail structure is the NNE-striking branch fault of Tan-Lu strike-slip fault zone. The NE-striking secondary extensional faults converged to the primary strike-slip fault. Fault activity analysis shows that both the primary and secondary faults intensively activated during the third Member of the Shahejie Formation (42~38 Ma). In the Weixinan area, the NE-striking Weixinan fault is the primary fault of the horsetail structure, which is an extensional fault. A large amount of EW-striking secondary extensional faults converged to the primary NE-striking Weixinan fault. Fault activity analysis shows that NE-striking primary fault intensively activated during the second Member of the Liushagang Formation (48.6~40.4 Ma), whereas the EW-striking secondary faults intensively activated during the Weizhou Formation (33.9~23 Ma). The different structure and evolution of the horsetail structure in the Liaodong Bay area and Weixinan area are mainly resulted from the regional tectonic settings. About 42 Ma, the change of subduction direction of the Pacific plate and the India-Eurasian collision resulted in the right-lateral strike-slip movement of NNE-striking Tan-Lu fault and the formation of NE-striking extensional faults along the bend of the strike-slip fault, therefore, the horsetail structure of Liaodong Bay area formed. However, the formation of the horsetail structure of Weixinan area is related to the clockwise rotation of extension stress in the South China Sea (SCS): 1) During Paleocene to M. Eocene (65~37.8 Ma), the retreat of Pacific plate subduction zone resulted in the formation of NW-SE extensional stress field in the north margin of the SCS, NE-striking primary fault of horsetail structure formed; 2) During L. Eocene to E. Oligocene (37.8~28.4 Ma), the change of subduction direction of the Pacific plate and the India-Eurasian collision resulted in the clockwise rotation of extension direction from NW-SE to N-S in the north margin of the SCS, a large amount of EW-striking secondary faults of horsetail structure formed, and the horsetail structure was totally formed in the Weixinan area until this stage.</p>

scholarly journals LONG TERM MORPHOLOGICAL EVOLUTION OF THE GOLD COAST SEAWAY: HISTORICAL AND NUMERICAL ANALYSIS

2012 ◽  
Vol 1 (33) ◽  
pp. 28 ◽  
Author(s):  
Mahnaz Sedigh ◽  
Rodger Tomlinson ◽  
Aliasghar Golshani ◽  
Nick Cartwright
Keyword(s):  
East Coast ◽  
Morphological Evolution ◽  
Gold Coast ◽  
Shoreline Erosion ◽  
Tidal Inlets ◽  
The North ◽  
Beach Width ◽  
The Pacific ◽  
The Pacific Ocean

The Gold Coast Seaway is one of two main tidal inlets located on the Australian East coast at a longitude of 27°56’10S and a latitude of 153°25’60E linking an intra-coastal waterway known as The Broadwater with the Pacific Ocean.. The reasons for construction of the Gold Coast Seaway and the associated sand by-passing system in the 1980s were stabilising the entrance, maintaining a safe navigable channel, preventing shoreline erosion to the north and maintaining an adequate beach width to the south.

scholarly journals Analisis Pertumbuhan Dan Persebaran Penduduk Provinsi Sumatera Utara Berdasarkan Hasil Sensus Penduduk Tahun 2010

2014 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Mbina Pinem
Keyword(s):  
Population Growth ◽  
West Coast ◽  
East Coast ◽  
Secondary Data ◽  
The West ◽  
The North ◽  
Spatial Approach ◽  
North Sumatra ◽  
Coast Region

This research porposes to understand growth and spread of population in Province of North Sumatra. The method used here is decriptive analysis of secondary data with the spatial approach. Whereas the object of research are the number of population, the population growth, and spread of population of North Sumatra Province based on 2010 census of Indonesian pupulation. The outcome of research represents that the population growth of Province of North Sumatra from 2000 to 2010 average of 1,22 percent per year. Then, the highest population growth found in Regency of Middle Tapanuli (2,46 percent), followed by Regency of Karo (2,17 percent), and South Tapanuli Regency (2,12 percent). Meanwhile the lowest population growth found in Siantar Town (-029 percent) and followed by Toba Samosir Regency (0,38 percent) and Simalungun Regency (-0,46 percent). As the spread of pupulation in the North Sumatra Province is not prevalent, as the settlements spreads nearly 62,87 percent on the east coast region, whereas only 3,05 percent on the west coast, and the rest 4,85 percent on the Nias Islands.

scholarly journals Neotectonics, Kinematics, and Evolution of the Vernon, Awatere, and Cloudy Faults of the Marlborough Fault System, New Zealand

2021 ◽  
Author(s):  
◽  
Timothy David Bartholomew
Keyword(s):  
Late Quaternary ◽  
Normal Component ◽  
Slip Rate ◽  
Vertical Axis ◽  
Fault System ◽  
Clockwise Rotation ◽  
The North ◽  
Fault Network ◽  
Seismic Lines ◽  
Good Agreement

<p>The coastal Awatere, Vernon, and Cloudy faults are bent and mutually intersecting, forming a complexly deforming dextral-oblique fault network. To try to explain the kinematic, paleoseismic and evolutionary complexities of this network, I present the results of an investigation into the rates, timing, and direction of slip on the faults within the network; which bifurcate eastwards from the central Awatere fault at the northeast end of the Marlborough Fault System. Displacements of dated and nondated late Quaternary features by the three faults were measured both onshore and offshore, constraining the kinematics of the fault network. The Vernon fault oddly maintains a dextral-reverse structure although it varies over 90° in strike and the Cloudy and coastal Awatere faults change from nearly pure strike slip to having a normal component eastwards. These data indicate that the fault-bounded blocks between the coastal Awatere, Vernon and Cloudy faults are rotating anticlockwise about a vertical axis relative to the block to the north of the fault system. Slip-rate data also indicate that of the 6 ± 1 mm/yr of slip on the central Awatere Fault, 1.1 ± 0.6 mm/yr has been partitioned ENE onto the coastal Awatere Fault and <4.9 mm/yr has been partitioned NNE onto the Vernon Fault. A slip-rate shortage in the splays of the Vernon Fault in the Vernon Hills is caused by a combination of unsighted faults and rotation of smaller splay-bounded blocks within the Vernon Hills. Paleoseismic records on the Vernon Fault were analysed onshore in a trench and offshore on seismic lines, with the records in good agreement. 3-5 earthquakes are recognised at different sites, with the last earthquake occurring 3.3 ka and a mean recurrence interval of 3-4 ka on the Vernon Fault. When combined with the paleseismic records from the Awatere and Cloudy faults I find that separate faults ruptured at similar times, suggesting a connectivity of the faults, as separate faults could mutually rupture during one earthquake or an earthquake could subsequently trigger an earthquake on a nearby fault. Finally I present the finite slip of geologic units and use these data as well as the late Quaternary slip data to describe the evolution of the fault network. I propose that the fault network at the NE end of the Awatere fault has stepped northwards into several splays, caused by clockwise rotation of the NE tips of the Marlborough faults.</p>

scholarly journals THE INTRAPLATE VOLCANO-TECTONIC ACTIVITY IN NORTH-EASTERN AND SOUTH SECTORS OF THE PACIFIC LITHOSPHERIC PLATES WITH THE CONNECTION OF THE CHANGE OF ITS RELATIVE MOTION

2021 ◽  
Vol 49 (4) ◽  
pp. 102-127
Author(s):  
E. G. Mirlin ◽  
T. I. Lygina ◽  
E. I. Chesalova
Keyword(s):  
Relative Motion ◽  
Sedimentary Cover ◽  
Oceanic Lithosphere ◽  
Pacific Plate ◽  
Fault System ◽  
Tectonic Activity ◽  
The North ◽  
The Pacific ◽  
North Eastern ◽  
Absolute Age

The analysis of altimetric data in combination with bathymetry and gravimetry materials in the north-eastern and southern sectors of the Pacific Ocean, as well as detailed data on the underwater relief, the structure of the sedimentary cover, the composition and absolute age of basalts obtained within the area of domestic geological exploration for ferromanganese nodules (the Clarion-Clipperton zone) is carried out. Structural trends formed by local cone-shaped local structures of presumably volcanic nature, grouped along transform faults belonging to various stages of the kinematics of the Pacific Plate, have been traced in the structure of the oceanic lithosphere at various scale levels. The first trend corresponds to the extension of the fault system corresponding to the spreading system on the crest of the East Pacific rise before the restructuring of its planned geometry in the Paleocene-Eocene, the second coincides with their extension after the change in the relative movement of the Pacific Plate. The trends are characterized by planned disagreement, and an increase in the number of seamounts is observed in the areas of their intersection. Within the area of detailed studies, obvious signs of volcanic-tectonic activity were revealed: high dissection of the underwater relief, hills of different heights with steep slopes, whose volcanic nature is confirmed by differentiated basalts raised from their slopes, the absolute age of which indicates the multistage outpourings that occurred in an intraplate environment. The angular velocity of rotation of the spreading axis and the linear velocity of its advance with changes in the kinematics of the Pacific plate are estimated and possible reasons for changes in its relative motion are considered. An improved scheme of adaptation of the spreading zone to a change in the direction of relative plate movement is proposed, acc0ording to which an essential factor of intraplate volcanic-tectonic activity is the relaxation of stresses in the plate caused by external influence on it.

New geophysical data from the northern Cordillera: preliminary interpretations and implications for the tectonics and deep geology

1994 ◽  
Vol 31 (6) ◽  
pp. 891-904 ◽  
Author(s):  
C. Lowe ◽  
R. B. Horner ◽  
J. K. Mortensen ◽  
S. T. Johnston ◽  
C. F. Roots
Keyword(s):  
Gravity Data ◽  
Field Studies ◽  
Geophysical Data ◽  
Fault System ◽  
Tectonic Activity ◽  
Denali Fault ◽  
The North ◽  
The Pacific ◽  
Proterozoic Basement ◽  
Seismic Sections

In this paper we analyze recently acquired geophysical data from the northern Cordillera and their relation to the mapped geology. A prominent gravity high (> −45 mGal (1 Gal = 1 cm/s2)) coincides with a magnetic low and an aseismic region in west-central Yukon where the underlying geology is dominated by quartzo-feldspathic rocks having moderate densities. Extension (~15%), magmatic underplating, and accretion of the anomalous region onto oceanic crust are three possible explanations.Magnetic, gravity, and seismicity data all show significant differences in the physical state of the crust on either side of the Tintina Fault and, together with geological data indicating large offset, suggest it was once a major crustal-scale strike-slip fault. The new gravity data also delineate an arcuate zone of steep gradients (up to 1.4 mGal/km) in the miogeocline, which may correlate with a west-dipping Proterozoic basement ramp mapped on deep seismic sections farther to the north and a transition from thin (east) to thick sediment cover (west). Seismicity data show that current tectonic activity is concentrated along the Pacific – North America plate margin in southwestern Yukon and adjacent Alaska and, although there is a marked decrease in activity inland of this margin, notable concentrations occur along the Denali Fault System and in the eastern miogeocline. There is a distinct absence of earthquakes in parts of the Selwyn Basin and in the northern Yukon–Tanana Terrane. Limited field studies suggest activity is confined to the upper 10–15 km of the crust.

SOME ASPECTS OF HILL COUNTRY FARMING ON THE EAST COAST

1984 ◽  
pp. 44-47
Author(s):  
J.W.S. Williams
Keyword(s):  
East Coast ◽  
The South ◽  
Personal View ◽  
The West ◽  
Hill Country ◽  
The North ◽  
Pros And Cons ◽  
Coast Region

The following is my personal view on what it is to be a European meat and wool farmer in the East Cape region. Many of my comments while applying in general to hill country in the whole of the Poverty Bay/East Coast region, are more specific to the area between Cape Runaway in the north, Gisborne City in the south, The Raukumara Range in the west, and the Coastline in the east. The total area is 830,000 hectares, and of this class 7 country (locally known as Category 2 and 3) makes up 45%. Class 8, or Category 4 land, has been excluded from the total area. I will refer to my own property as a typical example of this country, giving some of the pros and cons of farming this land.

scholarly journals Previsão Climática e de Ciclos Climáticos para o Estado do Ceará (Climate Prediction and Climate Cycles for the State of Ceará)

2013 ◽  
Vol 6 (4) ◽  
pp. 959
Author(s):  
Djane Fonseca Da Silva ◽  
Iuri Moreira Costa ◽  
Antônio Edgar Mateus ◽  
Aline Bezerra de Sousa
Keyword(s):  
Wavelet Analysis ◽  
Central Region ◽  
Pacific Decadal Oscillation ◽  
East Coast ◽  
The State ◽  
Metropolitan Region ◽  
Maximum Rainfall ◽  
The Pacific ◽  
Geographical Regions ◽  
Coast Region

Através das Análises de Ondeletas, concluiu-se que todas as oito macrorregiões do estado do Ceará sofrem influencia das variações e escalas sazonais, interanuais e decadais. Comprovou-se que sazonalidade, ENOS, Dipólo do Atlântico, Ciclo de manchas solares e Oscilação Decadal do Pacífico influenciam as precipitações no estado do Ceará. Assim, foi possível prever os máximos de precipitação para cada região: Região de Baturité, em 2016, 2020-2022; na Região Metropolitana de Fortaleza, em 2014 e 2024; na Região Sertão Central, em 2024; na Região Litoral Leste/Jaguaribe, em 2024 e 2027; na Região Cariri/Centro Sul, em 2018 e 2020; na Região Sertão dos Inhamuns, em 2015; na Região Litoral Oeste em 2028 e para Região Sobral/Ibiapaba, em 2030. A B S T R A C T Through Wavelet analysis, was concluded that all eight geographical regions of the state of Ceará suffer influences of variations and seasonal scales, interannual and decadal. Proved that seasonality, ENSO, Atlantic dipole, cycle of sunspots and the Pacific Decadal Oscillation influence rainfall in the state of Ceará. Thus was possible to predict the maximum rainfall for each region: Region Baturite, 2016, 2020-2022, in the Metropolitan Region of Fortaleza, in 2014 and 2024, the Sertão Central Region, in 2024, in the East Coast Region / Jaguaribe in 2024 and 2027; Cariri Region/South Centre in 2018 and 2020, the Region of Sertão Inhamuns in 2015; West Coast Region in 2028 and Sobral / Ibiapaba in 2030. Keywords: Pacific Decadal Oscillation, ENSO, Wavelet Analysis

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