Cenozoic Geology Research Articles

The Andes

Dr C. M. Bell has provided the following Introduction to the published papers: The Andes have been described as typical of an orogenic belt produced by subduction of an oceanic plate beneath a continental margin. Models of Andean geological evolution are, however, commonly poorly constrained due to the limited amount of data available from this very large area. Much research has been directed towards specific problems such as the magmatic rocks, but knowledge and understanding of many other aspects of Andean geology are still in their infancy. The purpose of the meeting of 5 October was to encourage geologists currently working in the Andes to provide up-to-date accounts of research in progress. Consequently the resulting collection of papers covers a wide range of topics and geographical areas. A major problem of Andean geology is the relative inaccessibility of much of the published data. This results both from language barriers and the limited distribution of some South American publications. One of the aims of this set of papers is to provide access to aspects of this widely scattered and somewhat obscure literature. The authors of the first two papers both consider aspects of Andean subduction. Wortel highlights the fact that despite a relatively constant convergence rate along the length of South America the late Cenozoic geology shows distinct variations in seismicity, tectonics and magmatic activity. He considers that the main factor controlling these variations is the age of subducted lithosphere. A lesser factor is the subduction of aseismic ridges and seamount

Middle Paleozoic to Cenozoic geology and tectonic evolution of the northwestern Himalaya

Previously published data and data collected by the authors from the northwestern Himalaya are summarized and assessed. The account focuses on Kohistan and the Karakorum Range in Pakistan, and on Ladakh and the Zanskar Range in India. Five palaeotectonic units are recognized. From south to north these are: 1. (1) Palaeozoic-Eocene continental shelf sequence on the northern margin of the Indian continent; 2. (2) a Triassic-Jurassic continental slope sequence: the Lamayuru unit of the Indus zone and of the Spongtang klippe; 3. (3) the Cretaceous-Tertiary Kohistan-Ladakh magmatic arc, which includes the Kokistan sequence, the Ladakh batholith, the Dras unit, the Spongtang klippe, the Indus molasse unit and the Shyok zone; 4. (4) the Karakorum batholith: a late Tertiary zone of granitoid magmatism and metamorphism; 5. (5) a PalaeozoicMesozoic continental shelf and slope sequence deposited on the southern margin of an Asian continent. The following sequence of events is tentatively proposed: 1. (1) Permian-Carboniferous continental rifting; 2. (2) Triassic-Jurassic collapse of continental shelf, and formation of deep (oceanic?) basin; 3. (3) Cretaceous formation of Kohistan-Ladakh magmatic arc, in response to subduction from the south as ocean closed; 4. (4) late Cretaceous-Eocene emplacement of Kohistan arc and of thrust sheets of Indus zone (magmatic arc units and Lamayuru unit) southwards onto Indian continental margin, as India approached and collided with magmatic arc; 5. (5) silicic phases of Ladakh batholith (Palaeocene-Eocene) and Karakorum batholith (Miocene) may be related to subduction of oceanic basin between magmatic arc and Asian margin. Alternatively, they are late- and post-collisional products; 6. (6) the Shyok zone, between the Ladakh and Karakorum batholiths, was emplaced to the south in Oligocene or Miocene time; 7. (7) final collision between India, the magmatic arc and Asia in Oligocene-Miocene time was followed by continued crustal shortening which disrupted thrust units.

Late Mesozoic-Cenozoic geology of the Ross Sector, Antarctica (extended abstract)

Abstract Knowledge of the late Mesozoic and Cenozoic geology of Antarctica is still in its infancy, compared with that of other continents. While Precambrian-jurassic rocks are relatively well exposed in the highlands of the continent, the Cretaceous and Cenozoic rocks (except for the Antarctic Peninsula and Marie Byrd Land) are found near or below sea level and are often obscured by sheet and shelf ice. Geophysical evidence indicates that there are probably extensive areas of Cretaceous and Cenozoic sediments in the continental shelves, particularly around the Weddell and Ross seas. The most extensive studies carried out so far have been in the Ross Sector, where analysis of exposures and core material has provided important insights into the structure and history of the Ross Sea continental shelf and the Transantarctic Mountains. Early studies provided detailed accounts of glacial sediments and erosional features of the Transantarctic Mountains, glaciomarine sediments and palaeontology of coastal areas ...

Mesozoic and Cenozoic Geology of Georgia Coastal Plain: ABSTRACT

Mesozoic and Cenozoic Geology of Georgia Coastal Plain: ABSTRACT

Mesozoic – early Cenozoic volcanism, plutonism, and mineralization in southern British Columbia: A plate tectonic synthesis

Three time–space profiles have been constructed using geologic data from British Columbia between 49° N and 56° N. They illustrate variations across the Cordillera, (1) in the stratigraphic and tectonic setting of volcanism, (2) in the age and modal type of granitoids, and (3) in the distribution and types of copper and lead deposits related to volcanic and plutonic rocks. These profiles provide the basis for a plate tectonic synthesis of the Mesozoic–Cenozoic geology, illustrated by six true-scale cross sections.The preferred model has, in the Triassic, two eastward-dipping subduction zones, giving rise to the copper-rich Karmutsen and Nicola–Takla volcanics respectively. After collision of the two volcanic belts by the Early Jurassic, a single eastward-dipping subduction zone remained active until the Eocene. Magmas produced by partial melting and fractionation of subducted lithosphere occurred across the western 300 km of the Cordillera, leading to thickening of the crust, and eventually to anatectic melting to generate large batholiths now containing pendants of volcanics. Jurassic and later geologic and metallogenic events across the eastern 500 km of the Cordillera are the results of an increased heat flux through inhomogeneous crust of varying thickness, comprised of relict ocean floor, continental margin sediments, older volcanics, and ancient cratonic basement. This results in patterns of metamorphism, volcanism, and plutonism which have no simple spatial relationship to the subduction zone.

Intraplate tectonics of the western North American plate

Fault-plane solutions, Cenozoic geology, and in-situ stress measurements are used to infer contemporary extension between subplates of the western North American plate. Intraplate, northwest extension is accommodated by strike-slip and oblique normal faulting along present-day seismic zones. Cenozoic volcanism, facilitated by regional extension above a subducting plate, may have spread radially outward from the northern Great Basin to form a continental triple junction with the principal arms: the central Great Basin, the Snake River Plain and a southeast-trending zone of rhyolite domes in the southern Columbia Plateau.

Cenozoic geology of the Yerington district, Nevada, and implications for the nature and origin of Basin and Range faulting

Research Article| February 01, 1977 Cenozoic geology of the Yerington district, Nevada, and implications for the nature and origin of Basin and Range faulting JOHN M. PROFFETT, JR. JOHN M. PROFFETT, JR. 1Anaconda Company, 1849 West North Temple, Salt Lake City, Utah 84116 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1977) 88 (2): 247–266. https://doi.org/10.1130/0016-7606(1977)88<247:CGOTYD>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation JOHN M. PROFFETT; Cenozoic geology of the Yerington district, Nevada, and implications for the nature and origin of Basin and Range faulting. GSA Bulletin 1977;; 88 (2): 247–266. doi: https://doi.org/10.1130/0016-7606(1977)88<247:CGOTYD>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract In the Yerington district, western Nevada, pre-Tertiary rocks are overlain by an Oligocene ignimbrite sequence and Miocene andesites. Basin and Range normal faulting began in Miocene time, as andesitic volcanism died out (17 to 18 m.y. ago), and has continued to the present. The faults dip east and are curved, concave upward, with net displacements in a nearly east-west direction. Movement on the curved faults has resulted in steep westward tilting of the Miocene andesites and of all older rocks. Alluvium and 8- to 11-m.y.-old basalt flows deposited during the period of faulting are tilted gently west. The oldest faults, which dipped steeply east when they were active, are now inactive and dip gently eastward as a result of westward tilting on other faults. Younger faults dip more steeply east, and the youngest faults, those responsible for present Basin and Range topography, are the steepest. More than 100 percent of east-west extension has taken place across the district because of normal faulting. The rate of extension was most rapid between 17 and 11 m.y. ago and was slower after 11 m.y. ago. The extension is deep seated rather than thin skinned and apparently involves thinning of the crust. Several theories of origin for Basin and Range structure can be rejected because of the field data at Yerington, and the theory that Basin and Range structure was caused by a continental spreading axis best fits the data. Basin and Range spreading seems to have been most active between the projections of the Mendocino and Murray fractures. It may have first started south of the Great Basin, when these fractures were farther south relative to the continent and when the oceanic spreading axis that had been between these fractures was interacting with the continent. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Influence of cenozoic geology on mass movement and sediment yield response to forest removal, North Westland, New Zealand

Clear-felling of beech-podocarp-hardwood forests and their replacement withP. radiata plantations on steep, dissected hill country underlain by massive, late-Tertiary sandstone and siltstone has resulted in an increase in denudation rate from c. 100 m3/km2/a to c. 4000 m3/km2/a. Landslide densities increased from 1/km2 to 20/km2. Forest operations of this nature on topographically similar areas underlain by late-Pleistocene and early-Pleistocene gravels have been followed by less-severe increases in mass-movement. Analyses of slope stability using the infinite slope model indicate that slopes greater than 25° underlain by late-Tertiary sandstone are unstable when saturated, unless additional shear strength is provided by a network of tree roots. Principal causes of this instability are 1) the impermeable sandstone promotes regolith saturation during moderatesized rainstorms (1 – 2 yr return period), 2) the sandstone surface is smooth, planar, coated with an allophane-rich organic clay layer, and is rarely pentrated by tree roots; shear strength at the regolith-sandstone interface is low.

Late Cenozoic Geology of the Payson Basin, Gila County, Arizona

Late Cenozoic Geology of the Payson Basin, Gila County, Arizona

Eustatic and Climatic History of the Adelaide Area South Australia: A Discussion

W. T. Ward's paper (1965) contains many statements about the late Cenozoic geology of the Willunga and Noarlunga basins that we believe are incorrect. The investigation of this complex area is a useful contribution, and the attempted synthesis of geology, geomorphology, and pedology is praiseworthy, but we consider that Ward has ignored important field evidence and has achieved a reconstruction of events that is not in accord with the facts. Our own investigations in South Australia are not so advanced that we can explain and

Late Cenozoic Geology of Hindu Canyon, Arizona

Late Cenozoic Geology of Hindu Canyon, Arizona

Cenozoic Stratigraphy and Structural Geology, Northeast Yellowstone National Park, Wyoming and Montana

Cenozoic eruptive rocks and terrestrial sediments were deposited on a structurally complex basement of Precambrian, Paleozoic, and Mesozoic rocks in the Yellowstone Park region. Eruption of lower Cenozoic andesitic breccias and tuffs appears o t have been cyclic, for the pyroclastic rocks become more mafic up-section with an increase in the relative abundance of breccia beds and decrease in tuff units. As each cycle proceeded, less silicic and more mafic material was ejected. The writer suggests that the cycles represent periodic tapping and drawing off of an upper, volatile-rich fraction of the source magma. A major hiatus separates the lower Cenozoic rocks from upper Cenozoic rhyolites and associated rocks in northern Yellowstone Park which are believed to be Pliocene and younger. At least five phases of deformation can be recognized in the map area: (1) Precambrian metamorphism, (2) Lancian to early Eocene Laramide folding and faulting, (3) middle Eocene fracturing and normal faulting, (4) post-middle Eocene prelate(?) Pliocene normal faulting, and (5) post-late(?) Pliocene normal faulting of rhyolitic welded tuffs.

Cenozoic Geology of the Colorado Plateau with Respect to Uinta Basin, Utah

Cenozoic Geology of the Colorado Plateau with Respect to Uinta Basin, Utah

Pliocene Stratigraphy of the Northern End of the Kitakami Mountains, Northeastern Japan:Cenozoic Geology of the Northern Margin of the Kitakami Mountains, II

Pliocene Stratigraphy of the Northern End of the Kitakami Mountains, Northeastern Japan:Cenozoic Geology of the Northern Margin of the Kitakami Mountains, II

LATE CENOZOIC GEOLOGY OF THE LOWER COLUMBIA RIVER VALLEY, OREGON AND WASHINGTON

Research Article| January 01, 1952 LATE CENOZOIC GEOLOGY OF THE LOWER COLUMBIA RIVER VALLEY, OREGON AND WASHINGTON W. D LOWRY; W. D LOWRY VIRGINIA POLYTECHNIC INSTITUTE, BLACKSBURG, VA.; UNIVERSITY OF OREGON, EUGENE, OREGON. Search for other works by this author on: GSW Google Scholar E. M BALDWIN E. M BALDWIN VIRGINIA POLYTECHNIC INSTITUTE, BLACKSBURG, VA.; UNIVERSITY OF OREGON, EUGENE, OREGON. Search for other works by this author on: GSW Google Scholar Author and Article Information W. D LOWRY VIRGINIA POLYTECHNIC INSTITUTE, BLACKSBURG, VA.; UNIVERSITY OF OREGON, EUGENE, OREGON. E. M BALDWIN VIRGINIA POLYTECHNIC INSTITUTE, BLACKSBURG, VA.; UNIVERSITY OF OREGON, EUGENE, OREGON. Publisher: Geological Society of America Received: 30 Jan 1951 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1952, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1952) 63 (1): 1–24. https://doi.org/10.1130/0016-7606(1952)63[1:LCGOTL]2.0.CO;2 Article history Received: 30 Jan 1951 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation W. D LOWRY, E. M BALDWIN; LATE CENOZOIC GEOLOGY OF THE LOWER COLUMBIA RIVER VALLEY, OREGON AND WASHINGTON. GSA Bulletin 1952;; 63 (1): 1–24. doi: https://doi.org/10.1130/0016-7606(1952)63[1:LCGOTL]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Late Cenozoic formations in the lower Columbia River drainage basin constitute one of the best records of the terrestrial history of Western North America. The main events within the Cascade Mountains and westward to the Pacific Ocean, which culminated in the Cascadian Revolution, are: Columbia River basaltic lavas were erupted from fissures during the middle Miocene upon a low-lying terrain of older Cenozoic sedimentary and volcanic rocks. Marine sediments of the Astoria formation were deposited just prior to extrusion in what is now the seaward part of the valley. The flows interfinger with beds which in general overlie the marine members of the Astoria formation.Limonite beds and associated clastic sediments were deposited in depressions locally developed on the lava plain.Additional lavas were extruded in the bog areas and perhaps on other parts of the lava plain.While the Columbia River basaltic terrain lay near sea level, the uppermost basalt was extensively laterized to ferruginous bauxite. The Columbia River had established essentially its present course at or near the margin of the lava plain, but erosion prior to deformation was of little consequence.Northerly trending open folds were produced in the basalt with those near the axis of the Cascade Range showing the greatest effect of the compression. Contemporaneously, anticlinal highs were modified by erosion and the lower part of the Troutdale formation was deposited in downwarps along the Columbia River while similar sediments were laid down in tributary valleys. Intercalated pyroclastics and flows herald the start of widespread Cascade volcanism. Basic lavas and pyroclastics were erupted from numerous vents including the major cones. All these events probably took place in the first half of the Pliocene.Additional sediments were deposited as sea level rose in later Pliocene time. Most of the present valley areas were covered with fluviatile sediments and the rivers established their present courses on or from such fills. Most of the Cascade volcanic activity had apparently taken place before the Portland Hills silt member of the Troutdale was deposited in the late (?) Pliocene time.Differential uplift began in late (?) Pliocene time and has continued to the present. The cutting of the Columbia River Gorge is the result of uplift which near the axis of the Cascade Range has been more than 2500 feet. Uplift in the Coast Range has been somewhat less.Downcutting by the Columbia River during the (?) early Wisconsin, as a result of a eustatic lowering of sea level, amounted to approximately 600 feet. Deposition of the Portland gravels with their glacial erratics and contemporaneous sediments occurred with the ensuing rise in sea level.Subsequent uplift in the Portland area has amounted to about 400 feet. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Preliminary Observations on the Cenozoic Geology of Yunnan*

Preliminary Observations on the Cenozoic Geology of Yunnan^*

Geology and Archæology in South-Eastern Asia

IN another column of this issue of NATURE (see p. 275) there appears a communication from Dr. H. de Terra, Dr. H. L. Movius and Father Teilhard de Chardin of far-reaching significance for the study of early man in Eastern Asia. The investigations of the joint Yale-Cambridge expedition to northern India, of which Dr. de Terra was leader, having established by the examination of the quaternary deposits a detailed subdivision of the Ice Age in that region, it was hoped that a like investigation of the quaternary gravels of the Irrawaddy Valley, in view of their central situation, might afford evidence for the integration of the cenozoic geology of southern China with that of India. Inferentially, it is obvious, such an integration would be of crucial value in establishing the chronological relation of the evidences of early man in the two regions. In 1937 an expedition under the joint auspices of the Academy of Sciences of Philadelphia and the Peabody Museum of Harvard University, with Dr. de Terra again as leader, entered upon the investigation of the quaternary deposits of the Irrawaddy. Not only was the expedition successful in establishing the resemblance of the Irrawaddy terrace system with that found in north-west India, while the soil records indicate the impact of corresponding climatic cycles, apparently superimposed on cyclic diastrophic processes, but it was also able, thanks to the co-operation of P. Teilhard de Chardin, the distinguished authority on the quaternary geology of China, to demonstrate as sufficiently assured the possibility that the late cenozoic history of the whole of the south-central Asiatic mass will be covered ultimately by a single stratigraphic and physiographic scheme. At the same time the subsequent visit of the expedition to Java made evident that the quaternary of that area differs in many respects from that of the mainland and that direct correlation will be less readily available there than was anticipated.

Cenozoic Geology of the Wenho‐Ssushui District of Central Shantung*

1. Syclinal warping at the end of the Cretaceous time?(Phase Ⅲ of Yenshan Movement?).Intermont sedimentation.Deposition of the lower and middle portions of the Kuanchuang Series during the Eocene(and early Oligocene?)time. 2. Block-faulting and progressive tilting during the late Oligocene time(Nanling Movement).Accumulation of the bajada breccias in con- nection with the faulting and the inauguration of the Tanghsien consequent drainage system. 3. Tanghsien to full maturity during the Miocene time. 4. Prolonged period of chemical weathering.Fossil soils with manganese-iron pisolites and karst surfaces formed(Pliocene). 5. Deposition of gravels(Late Pliocene?). 6. Z erosion of moderate dissection followed by the accumula- tion of the Concretionary Reddish Loams (Lower Pleis cene). 7. Chingshui dissection along old lines,followed by the deposition of brownish-gray loams and loess of the Malan epoch(Upper Pleistocene). 8. Present cycle of and deposition.

Topography and Cenozoic Geology in Corean Peninsula (2)

Topography and Cenozoic Geology in Corean Peninsula (2)

Topography and Cenozoic Geology in Corean Peninsula. (I)

Topography and Cenozoic Geology in Corean Peninsula. (I)