Late Cretaceous Early Eocene Research Articles

Cenozoic history of the Bering Sea and its northwestern margin

Tectonic reconstructions based on the geodynamic analysis of geologic, paleomagnetic, structural and kinematic data of Cenozoic age from the western Bering Sea region are proposed in the present paper. The most active tectonic and magmatic processes took place in the Komandorsky segment of the Bering Sea, exemplified by the Late Cretaceous–Early Eocene Olutorsky Arc and Eocene–Oligocene Govena–Karaginsky Arc, which was built on the structures of the Olutorsky Arc. A model of the complex collision of these two arcs with the paleocontinental margin, which considers rotations of the geological blocks from the various structural zones of the western margin of the Bering Sea in the horizontal plane (paleomagnetic data), was proposed by the authors. According to this model the collision of the flanks of the Olutorsky and Govena–Karaginsky arcs took place in the Eocene, before the collision of the central parts in the Miocene.

Break-up of the Greater Indo-Australian Continent and accretion of blocks framing South and East Asia

The Tibetan and ‘Sibumasu’ continental blocks rifted apart from the northern margin of Gondwanan Indo-Australia during the Permo-Carboniferous whereas, the IndoBurma-Andamans (IBA), Sikuleh, Lolotoi micro-continents did so during the Late Jurassic. This continental margin experienced glacial or cool conditions during the Permo-Carboniferous. The Tibetan and Sibumasu blocks drifted northward during mid-late Permian initiating opening of the Neo-Tethys. The arm of the Palaeo-Tethys located to the north of these blocks closed as these blocks were accreted to the South China and Indochina blocks which had separated from the same Gondwanan margin during early Palaeozoic. All these blocks were amalgamated to form the Cathaysialand. The Sibumasu block was accreted to the Indochina block, and the Tibetan Changtang block to Eurasia during the late Permian-mid Triassic. Contemporaneously Mesozoic Neo-Tethys expanded between the Indian, Lhasa and Changtang blocks. The Indian and Australian continents separated during the Cretaceous leading to the opening up of the Indian Ocean and closing of the Tethyan ocean. The Palaeo- and Neo-Tethyan sutures in Tibet, Yunnan, Myanmar, Laos-Thailand and Vietnam reveal the complex opening and closing history of the Tethys. IBA rotated clockwise from its earlier E-W orientation, because of dextral transcurrent fault movements which ensured faster northward movement of the Indian plate relative to Australia during late Cretaceous-early Eocene. Contemporaneous to India-Tibet terminal collision during early-mid Eocene there was thloeiitic-alkalic foreland volcanism (Abor and equivalents) at the leading edge of the Indian continent. Sustained post-collisional movement of the Indian plate, caused southward propagation of the Himalayan crystalline and frontal foreland thrust sheets. It also produced E-W trending folds and thrusts even in distal Central Indian Ocean areas as well as a clockwise rotation of the amalgamated SE Asian Cathaysian composite block. Dislocations of the 90 °E Ridge, indicate that the main compression occurred during early Eocene which was followed by movement since late Miocene. The ophiolite trail on IBA does not represent the eastern suture of the Indian continent. As a result of Late Oligocene oblique terminal collision between Sibumasu and 1BA, Mesozoic early Eocene ophiolites. their mid-Eocene cover and trench sediments occur as klippen on IBA. Oblique convergence between IBA and the Indian plate in turn produced an active subduction regime along the western margin of the Indo-Burma mobile belt and the Andaman-Java trench. The activity produced Neogcne-Quaternary volcanism. dextral strike-slip movement in Central Burma-Andaman-Sumatran region, and opened up the Andaman sea. Northward, the Shillong massif, representing NE prolongation of the Indian sub-continent, is technically juxtaposed against the northern end of IBA. The collision of these blocks might have uplifted the Shillong massif during Mio-Pliocene. Far eastward, the convergence was orthogonal between the Australian continent and the Indonesian Arc resulting emplacement of the Lolotoi continental rocks. Maubissi exotic blocks and ophiolitic rocks as nappe over the Timor shelf which possibly remained attached to the Australian continent.

The NE Atlantic margin; implications of late Mesozoic and Cenozoic events for hydrocarbon prospectivity

The study takes in the entire NE Atlantic margin (NEAM) but emphasizes the sparsely drilled More and Voring Basins. A network of Permo-Triassic and Jurassic basins was strongly overprinted by younger extensional episodes. At least three phases are probable--early Cretaceous, mid-Cretaceous and latest Cretaceous-early Eocene--between the late Jurassic and break-up. Substantial thicknesses of Cretaceous and Cenozoic strata along the margin have focused exploration interest on the late Cretaceous and Paleocene intervals as easily drillable targets. Reservoirs within these intervals were deposited as gravity-driven sand incursions into an overwhelmingly mud-prone environment. Sand pulses of Albian-Coniacian, Santonian-early Campanian and Paleocene age occur widely, and can be tied to the tectonic episodes. Vertical migration of hydrocarbons from known Jurassic source rocks is proven west of Shetlands, but in many parts of the margin remigration from intermediate reservoirs would be required to charge the shallower plays. Failing this, prospectivity will hinge on the presence of frontier source rocks, with best possibilities at Barremian, Aptian-Albian, Cenomanian-Turonian and Paleocene levels. Potential hydrocarbon traps were formed by pre-breakup extensional faulting and by post-breakup compression.

Long-term sediment accumulation in the Middle Jurassic–early Eocene Cordilleran retroarc foreland-basin system

Research Article| July 01, 1996 Long-term sediment accumulation in the Middle Jurassic–early Eocene Cordilleran retroarc foreland-basin system P. G. DeCelles; P. G. DeCelles 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar B. S. Currie B. S. Currie 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar Geology (1996) 24 (7): 591–594. https://doi.org/10.1130/0091-7613(1996)024<0591:LTSAIT>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation P. G. DeCelles, B. S. Currie; Long-term sediment accumulation in the Middle Jurassic–early Eocene Cordilleran retroarc foreland-basin system. Geology 1996;; 24 (7): 591–594. doi: https://doi.org/10.1130/0091-7613(1996)024<0591:LTSAIT>2.3.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 SocietyGeology Search Advanced Search Abstract The late Middle Jurassic–early Eocene (∼ 120 m.y.) sediment-accumulation history of the Cordilleran foreland basin in northern Utah exhibits a sigmoidal pattern on a rate vs. time plot, with moderate rates of accumulation during late Middle Jurassic, very low net rates during Late Jurassic–earliest Cretaceous, increasingly rapid rates during Early-middle Cretaceous, and low rates during Late Cretaceous–early Eocene time. This pattern is consistent with deposition in a prograding foreland-basin system that comprised integrated back-bulge, forebulge, foredeep, and wedge-top depozones. The upper Middle Jurassic represents the back-bulge depozone; the Upper Jurassic was deposited on the eastern flank of a flexural forebulge; the basal Cretaceous unconformity is the result of eastward migration of the forebulge; the thick, Lower-middle Cretaceous succession represents the foredeep depozone; and the Upper Cretaceous–early Eocene embodies the syndepositionally deformed wedge-top depozone. Previous models that explain Middle-Late Jurassic stratigraphic patterns in terms of foredeep subsidence (alone) and a Late Jurassic hiatus in crustal shortening in the Cordilleran orogen are shown to be neither necessary nor supported by evidence from the Cordilleran hinterland. 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.

Post-Laramide (Oligocene) uplift in the Wind River Range, Wyoming

In late Oligocene time, the crest of the Wind River Range was uplifted from an erosion surface that formed during Laramide (Late Cretaceous-early Eocene) deformation. This uplift created the highest peaks in the Wyoming foreland and is indicated by rejuvenation of the range as a sediment source and by the physiography of the peaks. Differential movement of basement blocks in the core of the range is identified by apatite fission-track data. We distinguish this deformation from earlier Laramide compression and Neogene normal faulting and speculate that it occurred when Precambrian shear zones were reactivated in response to local flexural stress in the Laramide subsidence-uplift couple.

The palaeorotation of the troodos microplate, cyprus, in the late mesozoic-early cenozoic plate tectonic framework of the Eastern Mediterranean

The Troodos ophiolite formed during the Late Cretaceous (Turonian) in a spreading setting above a northerly-dipping subduction zone. Palaeomagnetic data establish that the ophiolite experienced a 90° anticlockwise palaeorotation that occurred during the Late Cretaceous-Early Eocene interval During this period, the ophiolite was stranded adjacent to a generally south-facing continental margin, the remnants of which are preserved in south-west Cyprus (Mamonia Complex), southern Cyprus (Moni melange) and in northern Cyprus (Kyrenia Range). A review of field evidence from these Mesozoic basin margin units shows that strike-slip played a critical role in their Late Cretaceous-Early Tertiary deformation while magnetic and gravity surveys support the existence of major lineaments preserved at depth beneath these areas. Thus, in agreement with available palaeomagnetic data from mainland Turkey and Africa, the rotated crustal unit is believed to be relatively small with its boundaries probably located in the vicinity of Cyprus. In the favoured palaeorotation model, a small supra-subduction zone oceanic crustal unit was rotated about a pole located close to the exposed ophiolite complex. Fragments of the northern continental margin became attached to the rotating microplate along strike-slip lineaments and were then carried southward to their present position. In the light of the regional tectonic setting, it was probably the oblique consumption of crust beneath the ophiolite and/or a collision outside the present area of Cyprus that provided the necessary driving force for the palaeorotation.

Implications of pre-mesozoic orogeny in the geological evolution of the Himalaya and Indo-Gangetic Plains

An integrated geological analysis of the Himalaya and Indo-Gangetic Plains demonstrates that the Great Vindhyan Basin incorporating large parts of these morphotectonic units were uplifted into an uneven landmass due to the Pre-Mesozoic orogenic cycle. This uneven landmass was eroded off largely during a considerable part of the Devonian and Carboniferous thereby causing partial absence of sedimentary sequences of these periods except in parts of the Tethys Himalaya. The Late Paleozoic epeirogenic movements brought about renewed sedimentation in the Lesser and Tethys Himalayas in the Krol and Tethys Basins, respectively, which was terminated by the Himalayan Orogeny during Late Cretaceous—Early Eocene.

Transport Pressure Mark Mechanisms in the Late Cretaceous-Early Eocene Conglomerates, Northwestern Wyoming

In spite of rather intensive investigation into the origin of the Harebell (Late Cretaceous), Pinyon (Paleocene) and Pass Peak (Early Eocene) conglomerates in Jackson Hole and adjacent areas certain critical questions remain unanswered. The great thickness, coarseness and lateral extent imply an ancient source of considerable size and relief relatively near to present day Jackson Hole. Evidence for such a source is, however, equivocal and previous workers do not agree on its location. An even more perplexing question concerns the mechanisms by which such a huge volume of cobbles and boulders was transported from the source, wherever it was, to its depositional site. Such a system implies the existence of ancient alluvial fans on a scale unknown in modern environments.

Structural Evolution of the Honduras Continental Margin and the Sea Floor South of the Western Cayman Trough

The interpretation of 2,500 km of seismic-reflection profiles and its synthesis with the results of previous work reveal a four-stage development for the Honduras continental margin since late Mesozoic time. Late Cretaceous–early Eocene orogenesis deformed basement rocks and pre-orogenic units offshore Honduras. Following subsidence during middle Tertiary time, postorogenic units I and II blanketed the eroded preorogenic rocks, creating a distinct angular unconformity. The widespread distribution and uniform thickness of the postorogenic sediments suggest deposition during a tectonically quiescent period. Pliocene time marked the onset of block-faulting activity which fragmented the crust into irregular ridges and basins in northern Central America and along the Honduras continental margin and the western Cayman Trough. The continental shelf and slope of Honduras have been prograding since the Miocene Epoch; turbidites are now filling the proximal fault basins offshore Honduras. Assuming that regional tectonism and continental margin development are relatable to lithospheric plate interactions, the deformed preorogenic units are interpreted as having been buckled by convergent plate motions during Late Cretaceous–early Eocene time. Plate slippage may have lapsed during middle Tertiary time, as inferred from the nature of the postorogenic units. This phase of plate passivism was terminated during Pliocene time by block-faulting activity, which presumably represents the resumption of plate motions along the Cayman Trough that have persisted to the present in the northwestern Caribbean.

The Balkanids as an Instance of Back-Arc Thrust Belt: Possible Relation with the Hellenids

The Late Cretaceous calc-alkaline and Late Cretaceous–early Eocene alkaline (shoshonitic) magmatism of Srednogora in the Balkan chain of Bulgaria are interpreted as associated with an ancient active continental margin of Cordilleran (Andean) type. A tectonic evolution of back-arc thrust-belt type agrees, for the Balkanids, with the lack of large overthrust, ophiolite and radio-larite rock-type, eumiogeosyncline in this area. The distribution of magmatism from the Mesozoic to the Recent and the tectonic evolution of the Balkanic-Hellenic area suggest a discontinuous southward Tertiary migration of an arc-trench system away from the southwestern edge of the Rhodope massic to its present location in the eastern Mediterranean.

Continental Drift, IV: The Caribbean "Plate"

According to "the new global tectonics," the Caribbean Sea and the marginal lands surrounding it comprise one "lithosphere plate." Its eastern margin includes the Barbados Ridge, Lesser Antilles arc, and Aves Ridge; the western margin is composed of Central America and the Middle America Trench. These two margins are interpreted as subduction zones by "new global tectonics" advocates. The northern and southern margins are the alleged North Caribbean and South Caribbean faults, respectively. According to recent JOIDES drilling data, the Caribbean "plate" may be underlain by Late Cretaceous (75-85 m.y.) basaltic crust, and therefore is younger than both the Americas plate on the north, east, and south and the Cocos plate on the west. From this, some workers have inferred that the Caribbean formed by sea-floor spreading which separated North and South America. However, there is no spreading center in the Caribbean. Moreover, geologic and seismic data prove that the proposed North Caribbean and South Caribbean faults do not exist. La Désirade is a Jurassic or older island east of the Lesser Antilles. Barbados Ridge is an aseismic, pre-Late Jurassic salient of South America (that is, part of the so-called Americas plate) that parallels and lies just east of the alleged Lesser Antilles subduction zone. The stratigraphic units of Barbados are correlat-able with those of northern South America. Structural trends on Barbados strike east-northeast, are Late Cretaceous-early Eocene, and parallel those of South America. These facts show that the position of Barbados with respect to that of South America has not changed for more than 140 m.y. Yet "the new global tectonics" require that La Desirade and the Barbados Ridge must have been subducted more than 70 m.y. ago. On the basis of the facts presented here, the so-called Caribbean plate and the regions surrounding it have held the same positions relative to one another since pre-Jurassic (probably pre-Paleozoic) time. "The new global tectonics," therefore, are not applicable in the Caribbean area.

Stratigraphy of Late Cretaceous-Early Eocene, Seno Skyring--Strait of Magellan Area, Magallanes Province, Chile

Five surface sections and one subsurface section of Late Cretaceous--early Tertiary sedimentary rocks were studied in the Punta Arenas-Strait of Magellan area, southern Chile. The rocks range in age from middle Maestrichtian to early Eocene and consist of the following formations from base to top: Santa Ana Beds, Rio Blanco, Carrera, Chorrillo Chico, San Jorge, and Agua Fresca (eastern Brunswick Peninsula area); and Fuentes, Rocallosa, Chorrillo Chico, San Jorge, and Agua Fresca (Seno Skyring area). The Cretaceous-Tertiary boundary is in the Chorrillo Chico Formation which covers the entire area. The rocks studied are varieties of graywacke, siltstone, and argillite. Heavy-mineral studies indicate a varied source area including silicic plutons, metamorphic and gneissic rocks, and some volcanic terrane. Lithologic, paleoecologic, and geochemical data show that the transition from middle Maestrichtian to early Eocene was gradual. Generally, the depth of water in which the stratigraphic units were deposited decreased continually through time. Geochemical element analyses were made in an attempt to correlate the pre-Chorrillo Chico units in the Seno Skyring and Brunswick Peninsula areas. The study was limited and the results were not decisive. However, evidence was found to support correlation of the middle Rocallosa Formation with the Carrera Formation. The results obtained warrant further geochemical studies to aid correlation in the area. All evidence collected indicates that, before deposition of the Chorrillo Chico Formation, the Late Cretaceous basin in this area was bisected by a northeast-southwest-trending topographic ridge. Because of the presence of this ridge, the sedimentation histories in the northwestern and southeastern parts of the area differ, and units deposited on either side of the ridge are difficult to correlate.

Laramide igneous sequence and differentiation in the Front Range, Colorado

Research Article| January 01, 1938 Laramide igneous sequence and differentiation in the Front Range, Colorado T. S. LOVERING; T. S. LOVERING Search for other works by this author on: GSW Google Scholar E. N. GODDARD E. N. GODDARD Search for other works by this author on: GSW Google Scholar Author and Article Information T. S. LOVERING E. N. GODDARD Publisher: Geological Society of America Received: 22 Jul 1937 First Online: 02 Mar 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 1938 Geological Society of America GSA Bulletin (1938) 49 (1): 35–68. https://doi.org/10.1130/GSAB-49-35 Article history Received: 22 Jul 1937 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 T. S. LOVERING, E. N. GODDARD; Laramide igneous sequence and differentiation in the Front Range, Colorado. GSA Bulletin 1938;; 49 (1): 35–68. doi: https://doi.org/10.1130/GSAB-49-35 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 INTRODUCTIONGENERAL FEATURESThe Laramide1 (late Cretaceous—early Eocene) igneous rocks or “porphyries” of the Front Range are largely confined to a belt about 15 miles wide that extends diagonally across the pre-Cambrian core of the range, from Breckenridge northeast to Lyons (Fig. 1). The intrusives show a wide variety both of composition and of form. Dikes are abundant throughout the porphyry belt, but stocks are concentrated along the northwest side, and sills are almost confined to the sediments bordering the pre-Cambrian near Breckenridge and between Lyons and Boulder. South of Boulder, late Cretaceous surface flows and a few dikes and sheets occur near Golden. Co-extensive with the porphyry belt are important ore deposits of lead-silver, gold, gold-telluride, tungsten, and fluorspar.Many contributions have been made on local problems of petrology and petrography, and a few papers dealing with some of the broader regional aspects have been published, notably the . . . 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.