Initiation and evolution of forearc basins in the Central Myanmar Depression

2019 ◽  
Vol 132 (5-6) ◽  
pp. 1066-1082 ◽  
Author(s):  
Fulong Cai ◽  
Lin Ding ◽  
Qinghai Zhang ◽  
Devon A. Orme ◽  
Honghong Wei ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Upper Cretaceous ◽  
Upper Triassic ◽  
Forearc Basin ◽  
The West ◽  
Zircon Age ◽  
Shallow Marine ◽  
Western Margin ◽  
Forearc Basins ◽  
Structural High

Abstract The forearc basin in Myanmar is significant in understanding the development of continental forearc basins. We present stratigraphic, sandstone petrographic, and U-Pb detrital data from Upper Cretaceous–Eocene strata of Chindwin and Minbu sub-basins in the Central Myanmar Depression. The Upper Cretaceous lower Kabaw Formation consists of turbiditic conglomerate, sandstone, and mudstone in the Minbu sub-basin. The composition of conglomerates are mainly schist and subordinate quartz. Prominent detrital zircon age probability peaks are between 260 and 223 Ma, similar with that of Upper Triassic Pane Chaung turbidites and Kanpetlet schist on the West Burma plate. In the upper Kabaw Formation, turbiditic volcanic-rich sandstones have major age populations ranging from 103 to 70 Ma in both Minbu and Chindwin sub-basins. The Paleocene slope environment Paunggyi Formation, which overlies the Kabaw Formation, mainly consists of conglomerate, sandstone, mudstone, and tuff beds in the Minbu sub-basin. In contrast, the Paunggyi Formation in the Chindwin sub-basin is composed of sandstone and mudstone; major detrital zircon age populations from the Paunggyi Formation are between 100 and 60 Ma. Eocene strata in both basins are composed mainly of shallow marine to delta sandstone and mudstone. Major detrital zircon age populations are 100–36 Ma and 600–500 Ma. The Late Cretaceous–Eocene ages from Upper Cretaceous–Eocene strata overlap with igneous crystallization ages from the Western Myanmar Arc. We propose that the Chindwin and Minbu sub-basins developed as parts of a forearc basin along the west flank of Western Myanmar Arc (present coordinate). The forearc basin initiated in Albian time atop the continental West Burma plate due to the formation of a structural high along the western margin of West Burma plate.

Apercu geologique sur les collines de Boutenac (Aude)

1962 ◽  
Vol S7-IV (3) ◽  
pp. 362-379
Author(s):  
Alain Combes
Keyword(s):  
Upper Cretaceous ◽  
Upper Triassic ◽  
Normal Faulting ◽  
The West ◽  
Southern France ◽  
Sandy Limestone

Abstract The Boutenac hills in the northeastern Corbieres region of southern France, are part of the autochthonous foreland of the eastern Corbieres nappe. They are an isolated massif between the Paleozoic formations of the Alaric mountain on the west, and the Jurassic and Cretaceous formations of the Fontfroide chain on the east, entirely surrounded by alluvium. Structurally, they comprise Mesozoic formations on the east thrust over the Eocene on the west, on a fault that is the prolongation of the Saint Chinian frontal fault to the northeast. The Mesozoic formations comprise upper (?) Triassic shale and dolomite, sandy limestone, dolomite, and limestone; Jurassic red sandstones and shales; and upper Cretaceous transgressive clastics. The Eocene is limestone and marl overlain by continental conglomerate and molasse, transgressive on the west upon the Alaric Paleozoics. Folding and thrust and normal faulting are important in the structure.

scholarly journals The U-Pb detrital zircon signature of West Antarctic ice stream tills in the Ross embayment, with implications for Last Glacial Maximum ice flow reconstructions

2014 ◽  
Vol 26 (6) ◽  
pp. 687-697 ◽  
Author(s):  
Kathy J. Licht ◽  
Andrea J. Hennessy ◽  
Bethany M. Welke
Keyword(s):  
Last Glacial Maximum ◽  
Detrital Zircon ◽  
Ross Sea ◽  
Ice Sheet ◽  
Glacial Maximum ◽  
Ice Streams ◽  
The West ◽  
Zircon Age ◽  
Last Glacial ◽  
West Antarctic

AbstractGlacial till samples collected from beneath the Bindschadler and Kamb ice streams have a distinct U-Pb detrital zircon signature that allows them to be identified in Ross Sea tills. These two sites contain a population of Cretaceous grains 100–110 Ma that have not been found in East Antarctic tills. Additionally, Bindschadler and Kamb ice streams have an abundance of Ordovician grains (450–475 Ma) and a cluster of ages 330–370 Ma, which are much less common in the remainder of the sample set. These tracers of a West Antarctic provenance are also found east of 180° longitude in eastern Ross Sea tills deposited during the last glacial maximum (LGM). Whillans Ice Stream (WIS), considered part of the West Antarctic Ice Sheet but partially originating in East Antarctica, lacks these distinctive signatures. Its U-Pb zircon age population is dominated by grains 500–550 Ma indicating derivation from Granite Harbour Intrusive rocks common along the Transantarctic Mountains, making it indistinguishable from East Antarctic tills. The U-Pb zircon age distribution found in WIS till is most similar to tills from the west-central Ross Sea. These data provide new specific targets for ice sheet models and can be applied to pre-LGM deposits in the Ross Sea.

scholarly journals Project Westmar, A shallow marine geophysical survey on the West Greenland continental shelf

1979 ◽  
Vol 87 ◽  
pp. 1-29
Author(s):  
C.P Brett ◽  
E.F.K Zarudzki
Keyword(s):  
Continental Shelf ◽  
Geophysical Survey ◽  
The West ◽  
Shallow Marine ◽  
Western Margin ◽  
Sea Floor ◽  
West Greenland ◽  
Maximum Water ◽  
Shelf Margin ◽  
Morphological Relationship

An extensive shallow geophysical survey has been carried out on the West Greenland continental shelf between 64° and 69°30'N. Preliminary interpretation of the data reveals that between 64° and 67°30'N at least, the entire shelf was glaciated to its western margin during the Pleistocene, the glaciation processes leaving a variable (< 20-200 m thick) cover on the Tertiary sedimentary wedge underlying the shelf. A morphological relationship exists between the degree of sea floor roughness and the types of glaciation forms. The distribution and contacts of the three main shallow bedrock units in the area (Precambrian gneisses, Lower Tertiary volcanics and Tertiary sediments) are delineated. Widespread prograding is observed in sediments along the shelf margin. Extensive iceberg scouring of the sea floor is observed north of 67°30'N reaching a maximum water depth of 340 m.

Tectonic evolution of the central California margin as reflected by detrital zircon composition in the Mount Diablo region

2021 ◽  
Author(s):  
Jared T. Gooley ◽  
Marty Grove ◽  
Stephan A. Graham
Keyword(s):  
Sierra Nevada ◽  
Late Cretaceous ◽  
Late Miocene ◽  
Detrital Zircon ◽  
Middle Eocene ◽  
Forearc Basin ◽  
Zircon Age ◽  
Central California ◽  
Sierra Nevada Batholith ◽  
Early Paleogene

ABSTRACT The Mount Diablo region has been located within a hypothesized persistent corridor for clastic sediment delivery to the central California continental margin over the past ~100 m.y. In this paper, we present new detrital zircon U-Pb geochronology and integrate it with previously established geologic and sedimentologic relationships to document how Late Cretaceous through Cenozoic trends in sandstone composition varied through time in response to changing tectonic environments and paleogeography. Petrographic composition and detrital zircon age distributions of Great Valley forearc stratigraphy demonstrate a transition from axial drainage of the Klamath Mountains to a dominantly transverse Sierra Nevada plutonic source throughout Late Cretaceous–early Paleogene time. The abrupt presence of significant pre-Permian and Late Cretaceous–early Paleogene zircon age components suggests an addition of extraregional sediment derived from the Idaho batholith region and Challis volcanic field into the northern forearc basin by early–middle Eocene time as a result of continental extension and unroofing. New data from the Upper Cenozoic strata in the East Bay region show a punctuated voluminous influx (&gt;30%) of middle Eocene–Miocene detrital zircon age populations that corresponds with westward migration and cessation of silicic ignimbrite eruptions in the Nevada caldera belt (ca. 43–40, 26–23 Ma). Delivery of extraregional sediment to central California diminished by early Miocene time as renewed erosion of the Sierra Nevada batholith and recycling of forearc strata were increasingly replaced by middle–late Miocene andesitic arc–derived sediment that was sourced from Ancestral Cascade volcanism (ca. 15–10 Ma) in the northern Sierra Nevada. Conversely, Cenozoic detrital zircon age distributions representative of the Mesozoic Sierra Nevada batholith and radiolarian chert and blueschist-facies lithics reflect sediment eroded from locally exhumed Mesozoic subduction complex and forearc basin strata. Intermingling of eastern- and western-derived provenance sources is consistent with uplift of the Coast Ranges and reversal of sediment transport associated with the late Miocene transpressive deformation along the Hayward and Calaveras faults. These provenance trends demonstrate a reorganization and expansion of the western continental drainage catchment in the California forearc during the late transition to flat-slab subduction of the Farallon plate, subsequent volcanism, and southwestward migration of the paleodrainage divide during slab rollback, and ultimately the cessation of convergent margin tectonics and initiation of the continental transform margin in north-central California.

CONTINENTAL SHELF BASINS ON THE WEST TASMANIA MARGIN

1992 ◽  
Vol 32 (1) ◽  
pp. 231 ◽  
Author(s):  
A.M.G. Moore ◽  
J.B. Willcox ◽  
N.F. Exon ◽  
G.W. O'Brien
Keyword(s):  
Continental Shelf ◽  
Continental Slope ◽  
Late Cretaceous ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Strike Slip ◽  
Source Rocks ◽  
Fault System ◽  
The West ◽  
Shallow Marine

The continental margin of western Tasmania is underlain by the southern Otway Basin and the Sorell Basin. The latter lies mainly under the continental slope, but it includes four sub-basins (the King Island, Sandy Cape, Strahan and Port Davey sub-basins) underlying the continental shelf. In general, these depocentres are interpreted to have formed at the 'relieving bends' of a major left-lateral strike-slip fault system, associated with 'southern margin' extension and breakup (seafloor spreading). The sedimentary fill could have commenced in the Jurassic; however, the southernmost sub-basins (Strahan and Port Davey) may be Late Cretaceous and Paleocene, respectively.Maximum sediment thickness is about 4300 m in the southern Otway Basin, 3600 m in the King Island Sub-basin, 5100 m in the Sandy Cape Basin, 6500 m in the Strahan Sub-basin, and 3000 m in the Port Davey Sub-basin. Megasequences in the shelf basins are similar to those in the Otway Basin, and are generally separated by unconformities. There are Lower Cretaceous non-marine conglomerates, sandstones and mudstones, which probably include the undated red beds recovered in two wells, and Upper Cretaceous shallow marine to non-marine conglomerates, sandstones and mudstones. The Cainozoic sequence often commences with a basal conglomerate, and includes Paleocene to Lower Eocene shallow marine sandstones, mudstones and marl, Eocene shallow marine limestones, marls and sandstones, and Oligocene and younger shallow marine marls and limestones.The presence of active source rocks has been demonstrated by the occurrence of free oil near TD in the Cape Sorell-1 well (Strahan Sub-basin), and thermogenic gas from surficial sediments recovered from the upper continental slope and the Sandy Cape Sub-basin. Geohistory maturation modelling of wells and source rock 'kitchens' has shown that the best locations for liquid hydrocarbon entrapment in the southern Otway Basin are in structural positions marginward of the Prawn-1 well location. In such positions, basal Lower Cretaceous source rocks could charge overlying Pretty Hill Sandstone reservoirs. In the King Island Sub-Basin, the sediments encountered by the Clam-1 well are thermally immature, though hydrocarbons generated from within mature Lower Cretaceous rocks in adjacent depocentres could charge traps, providing that suitable migration pathways are present. Whilst no wells have been drilled in the Sandy Cape Sub-basin, basal Cretaceous potential source rocks are considered to have entered the oil window in the early Late Cretaceous, and are now capable of generating gas/condensate. Upper Cretaceous rocks appear to have entered the oil window in the Paleocene. In the Strahan Sub-Basin, mature Cretaceous sediments in the depocentres are available to traps, though considerable migration distances would be required.It is concluded that the west Tasmania margin, which has five strike-slip related depocentres and the potential to have generated and entrapped hydrocarbons, is worthy of further consideration by the exploration industry. The more prospective areas are the southern Otway Basin, and the Sandy Cape and Strahan sub-basins of the Sorell Basin.

Detrital zircon U-Pb ages and whole-rock geochemistry of early Paleozoic metasedimentary rocks in the Mongolian Altai: Insights into the tectonic affinity of the whole Altai-Mongolian terrane

2019 ◽  
Vol 132 (3-4) ◽  
pp. 477-494
Author(s):  
Xiaoping Long ◽  
Jin Luo ◽  
Min Sun ◽  
Xuan-ce Wang ◽  
Yujing Wang ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Age Distribution ◽  
Isotopic Analysis ◽  
Detrital Zircons ◽  
Cumulative Distribution ◽  
Early Paleozoic ◽  
Zircon Age ◽  
Western Margin ◽  
Metasedimentary Rocks ◽  
Mongolian Altai

Abstract The tectonic affinity of the terranes and microcontinents within the Central Asian Orogenic Belt (CAOB) remains controversial. The Altai-Mongolian terrane (AMT), as a representative tectonic unit in the Mongolian collage, plays a vital role in reconstructing evolution history of the CAOB. The well-preserved early Paleozoic sedimentary sequence covering in this terrane could be considered as a fingerprint to track its provenance and tectonic affinity. Here, we present new whole-rock geochemistry, detrital zircon U-Pb dating, and Hf isotopic analysis for the metasedimentary rocks from the Mongolian Altai in order to shed new light on the tectonic affinity of the AMT. The youngest detrital zircon ages and the regional intrusions constrain the depositional time of the Mongolian Altai sequence to between Late Silurian and Early Devonian, which is consistent with the Habahe group in the western Chinese Altai. The features of whole-rock geochemistry and the cumulative distribution curves of the detrital zircon age spectra indicate that the Mongolian Altai sequence was probably deposited in an active continental setting during early Paleozoic. The zircon age spectra of our samples are all characterized by a main age group in the early Cambrian (peak at 541 Ma, 522 Ma, 506 Ma and 496 Ma, respectively), subdominant age populations during the Tonian, as well as rare older zircons. The nearby Lake Zone of Ikh-Mongol Arc most likely provided plenty of early Paleozoic materials, the subdominant Neoproterozoic detrital zircons could be supplied by the felsic intrusions along the western margin of the Tuva-Mongol microcontinent, and the sparse older zircons may be derived from its basement material. The Precambrian age distribution of the AMT is quite similar to both the Tarim and Siberia cratons, but the Siberia Craton displays a closer resemblance in Hf isotopic composition with the AMT. Thus, we believe that the Siberia Craton contains a closer tectonic affinity with the AMT, and that the Tuva-Mongol microcontinent possibly rifted from the western margin of this craton after the Tonian. To the south of the AMT, recent studies indicated the Yili and Central Tianshan blocks in the Kazakhstan collage of the western CAOB likely have a closer affinity with Gondwana. Therefore, the microcontinents in the CAOB most likely derived bilaterally from both the Siberia Craton and the Gondwana supercontinent. Moreover, our Hf isotopic compositions indicate two significant continental growth events in the Tonian and early Paleozoic, respectively.

Remarques sur les caracteres et l'evolution de la paleogeographie de la zone brianconnaise au Secondaire et au Tertiaire

1953 ◽  
Vol S6-III (1-3) ◽  
pp. 105-121 ◽  
Author(s):  
Marcel Lemoine
Keyword(s):  
Upper Cretaceous ◽  
Upper Triassic ◽  
Lower Eocene ◽  
Western Margin

Abstract Discusses the stratigraphy and paleogeography of the Brianconnais zone in the vicinity of Briancon, France, particularly during the geanticlinal period (upper Triassic to lower Eocene). The geanticline was formed by a pre-Bathonian "pulsation" rather than by marked orogeny; its relief was always very low, and erosion and sedimentation were consequently weak. There were areas, not only at the western margin, but even in the axial and eastern portions of the Brianconnais zone, where sedimentation was continuous from the Callovian (Jurassic) to the upper Cretaceous or later; the stratigraphic breaks usually considered characteristic of the Brianconnais facies are lacking.

Detrital zircon age and biostratigraphic and chemostratigraphic constraints on the Ediacaran–Cambrian transitional interval in the Irkutsk Cis–Sayans Uplift, southwestern Siberian Platform

2020 ◽  
pp. 1-17
Author(s):  
Vasiliy V. Marusin ◽  
Alena A. Kolesnikova ◽  
Boris B. Kochnev ◽  
Nikolay B. Kuznetsov ◽  
Boris G. Pokrovsky ◽  
...  
Keyword(s):  
Siberian Platform ◽  
Detrital Zircon ◽  
Isotope Composition ◽  
Trace Fossils ◽  
Zircon Age ◽  
Shallow Marine ◽  
Carbonate Carbon ◽  
Carbon And Oxygen Isotope ◽  
Marine Carbonates ◽  
Isotopic Records

Abstract A number of ecological and geochemical transformations occurred during late Ediacaran and early Cambrian time, the effects of which are difficult to overestimate. However, the strong linkage of biostratigraphic and chemostratigraphic methods with lithofacies makes the localization of the Precambrian–Cambrian boundary and its correlation with lithologically contrasting sections highly debatable. We analyse the taxonomy and stratigraphic distribution of small skeletal fossils and trace fossils, the carbonate carbon and oxygen isotope composition, and U–Pb detrital zircon age in the Ediacaran–Cambrian transitional interval of the Irkutsk Cis–Sayans Uplift (southwestern Siberian Platform). This interval (Moty Group) comprises a transgressive succession with red-coloured alluvial to deltaic siliciclastic deposits (Shaman Formation) and overlying shallow-marine carbonates (Irkut Formation). The lower Irkut Formation hosts sporadic and poorly preserved tubular Cambrotubulus fossils, which are known from both the terminal Ediacaran Period (c. 550–541 Ma) and the Terreneuvian Epoch (541–521 Ma), and typical Fortunian trace fossils, including an index ichnotaxon of the Cambrian boundary Treptichnus pedum. The biostratigraphic and carbonate carbon isotope data and U–Pb concordia ages of 531.1 ± 5.2 Ma (mean weighted, 530.6 ± 5.3 Ma) of the five youngest zircon grains from the lower Irkut Formation indicate that at least the shallow-marine carbonates of the upper Moty Group correspond to the Cambrian Stage 2 (c. 529–521 Ma). In the Irkutsk Cis–Sayans Uplift, the Cambrian Period tentatively began before or during the accumulation of the alluvial to deltaic siliciclastic Khuzhir and Shaman formations, and this crucial divide remained unmarked in the palaeontological and isotopic records.

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