SHRIMP U–Pb geochronology of detrital zircons from the Treasure Lake Group — new evidence for Paleoproterozoic collisional tectonics in the southern Hottah terrane, northwestern Canadian Shield

2005 ◽  
Vol 42 (5) ◽  
pp. 833-845 ◽  
Author(s):  
S S Gandhi ◽  
O van Breemen
Keyword(s):  
Middle Part ◽  
Detrital Zircons ◽  
Slave Craton ◽  
The North ◽  
Quartz Arenite ◽  
Continental Arc ◽  
Wide Range ◽  
Depositional Age ◽  
Age Range ◽  
New Evidence

The recently defined Treasure Lake Group is a platformal sedimentary sequence more than 3 km thick that was deformed and metamorphosed prior to formation of the Great Bear continental arc during 1875–1845 Ma. The group is exposed as remnants in the southern part of the arc. Its basement is not exposed, but is interpreted to comprise the Paleoproterozoic Hottah terrane, which is exposed at Hottah Lake in the northern part of the arc. Studies in that region show that the Hottah terrane collided with the Archean Slave craton to the east ca. 1883 Ma following reversal of subduction polarity from west to east. Continued eastward subduction under the collision zone formed the Great Bear arc. The present study was undertaken to determine the age and provenance of the Treasure Lake Group. Thirty-nine detrital zircon grains from a sample of a quartz arenite unit in the middle part of the Treasure Lake Group were analyzed by SHRIMP (sensitive high-resolution ion microprobe). They show an age range from ca. 2729 to ca. 1880 Ma, with main modes at ca. 1895, 1985, 2090, and 2330 Ma. These data confirm a mainly Paleoproterozoic provenance for the group. The youngest group of five zircon analyses places the maximum depositional age at 1886 ± 8 Ma. The Treasure Lake Group is close to the north-trending Wopmay medial zone formed during collision of the Hottah terrane and the Slave craton. Deformation and metamorphism of the group can now be attributed to the collisional event. The group may in part be coeval with the Bell Island Bay and Akaitcho groups of the northern Hottah terrane, the lower parts of which were deposited ca. 1900 Ma. The wide range of detrital zircons ages found in this study is interpreted to reflect a complex Paleoproterozoic evolution of the Hottah terrane.

Preliminary detrital zircon U-Pb Geochronology of the Wasatch Formation, Powder River Basin, Wyoming

2019 ◽  
Vol 56 (3) ◽  
pp. 247-266
Author(s):  
Ian Anderson ◽  
David H. Malone ◽  
John Craddock
Keyword(s):  
River Basin ◽  
Detrital Zircon ◽  
Middle Part ◽  
Detrital Zircons ◽  
Powder River Basin ◽  
Zircon Age ◽  
Lower Eocene ◽  
The North ◽  
Mountain Front ◽  
Fluvial Sandstone

The lower Eocene Wasatch Formation is more than 1500 m thick in the Powder River Basin of Wyoming. The Wasatch is a Laramide synorgenic deposit that consists of paludal and lacustrine mudstone, fluvial sandstone, and coal. U-Pb geochronologic data on detrital zircons were gathered for a sandstone unit in the middle part of the succession. The Wasatch was collected along Interstate 90 just west of the Powder River, which is about 50 km east of the Bighorn Mountain front. The sandstone is lenticular in geometry and consists of arkosic arenite and wacke. The detrital zircon age spectrum ranged (n=99) from 1433-2957 Ma in age, and consisted of more than 95% Archean age grains, with an age peak of about 2900 Ma. Three populations of Archean ages are evident: 2886.6±10 Ma (24%), 2906.6±8.4 Ma (56%) and 2934.1±6.6 Ma (20%; all results 2 sigma). These ages are consistent with the age of Archean rocks exposed in the northern part of the range. The sparse Proterozoic grains were likely derived from the recycling of Cambrian and Carboniferous strata. These sands were transported to the Powder River Basin through the alluvial fans adjacent to the Piney Creek thrust. Drainage continued to the north through the basin and eventually into the Ancestral Missouri River and Gulf of Mexico. The provenance of the Wasatch is distinct from coeval Tatman and Willwood strata in the Bighorn and Absaroka basins, which were derived from distal source (>500 km) areas in the Sevier Highlands of Idaho and the Laramide Beartooth and Tobacco Root uplifts. Why the Bighorn Mountains shed abundant Eocene strata only to the east and not to the west remains enigmatic, and merits further study.

Latest Jurassic–earliest Cretaceous age for a fossil flora from the Latady Basin, Antarctic Peninsula

2006 ◽  
Vol 18 (2) ◽  
pp. 261-264 ◽  
Author(s):  
Morag A. Hunter ◽  
David J. Cantrill ◽  
Michael J. Flowerdew
Keyword(s):  
Antarctic Peninsula ◽  
Plant Material ◽  
Weddell Sea ◽  
Detrital Zircons ◽  
Fossil Flora ◽  
Fossil Plant ◽  
The North ◽  
Depositional Age ◽  
The Antarctic ◽  
Basin Margin

Dating Jurassic terrestrial floras in the Antarctic Peninsula has proved problematic and controversial. Here U–Pb series dating on detrital zircons from a conglomerate interbedded with fossil plant material provide a maximal depositional age of 144 ± 3 Ma for a presumed Jurassic flora. This is the first confirmed latest Jurassic-earliest Cretaceous flora from the Latady Basin, and represents some of the youngest sedimentation in this basin. The presence of terrestrial sedimentation at Cantrill Nunataks suggests emergence of the arc closer to the Latady Basin margin in the south compared to Larsen Basin in the north, probably as a result of the failure of the southern Weddell Sea to undergo rifting.

scholarly journals Detrital zircons and sediment dispersal in the eastern Midcontinent of North America

Geosphere ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 817-843 ◽  
Author(s):  
William A. Thomas ◽  
George E. Gehrels ◽  
Kurt E. Sundell ◽  
Stephen F. Greb ◽  
Emily S. Finzel ◽  
...  
Keyword(s):  
Age Groups ◽  
Appalachian Basin ◽  
Detrital Zircons ◽  
Illinois Basin ◽  
Sediment Dispersal ◽  
Accreted Terranes ◽  
Appalachian Orogen ◽  
Northern Edge ◽  
Depositional Age ◽  
Age Range

Abstract Results of detrital-zircon analyses (U-Pb ages and initial Hf values, εHft) of Mississippian–Pennsylvanian sandstones in the Michigan, Illinois, and Forest City basins are remarkably similar to data for coeval sandstones in the Appalachian basin, indicating dispersal of sediment from the Appalachian orogen through the Appalachian basin to the eastern Midcontinent during the late Paleozoic. The similarities of results include matches of the two most prominent age groups (1300–950 Ma and 490–350 Ma), as well as matches of the less abundant age groups. Comparisons of the data are from observations of probability density plots and multidimensional scaling of U-Pb age data and of εHft values. Despite the dominance of an Appalachian signature in all samples, some samples contain grains with ages that suggest intermittent additional sources. Four samples (three ranging in depositional age from Morrowan to Atokan–Desmoinesian in the Illinois basin, and one of Desmoinesian age in the Forest City basin), in addition to typical Appalachian age distributions, have prominent age modes between 768 and 525 Ma, corresponding in age to Pan-African/Brasiliano rocks in Gondwanan accreted terranes in the Appalachian orogen, suggesting intermittent dispersal from the Moretown terrane of the northern Appalachians. Sandstones in the Appalachian basin and those in the Midcontinent basins have very few grains with ages that correspond to the Alleghanian orogeny in the Appalachian orogen. Nevertheless, three sandstones each in the Illinois basin and Forest City basin with depositional ages of 312–308 Ma have a few zircon grains in the age range of 321 ± 5 to 307 ± 4 Ma. The nearly identical crystallization and depositional ages suggest reworking at the depositional sites of air-fall volcanic ash from the Alleghanian orogen, rather than fluvial transport from the orogen. The basal Pennsylvanian sandstones lap onto a regional unconformity around the northern rims of the Illinois and Forest City basins, suggesting sources for recycled grains. Along the northern edge of the Illinois basin, Ordovician sandstones beneath the unconformity may have contributed minor concentrations of Superior-age zircons in the basal Pennsylvanian sandstones. Basal Pennsylvanian sandstones in the Forest City basin lap onto Mississippian strata, suggesting possible recycling of zircons from eroded Mississippian sandstones.

U–Pb and Hf isotopic study of detrital zircons from the Lüliang khondalite, North China Craton, and their tectonic implications

2009 ◽  
Vol 146 (5) ◽  
pp. 701-716 ◽  
Author(s):  
XIAOPING XIA ◽  
MIN SUN ◽  
GUOCHUN ZHAO ◽  
FUYUAN WU ◽  
LIEWEN XIE
Keyword(s):  
North China Craton ◽  
North China ◽  
Detrital Zircons ◽  
Crustal Material ◽  
Isotopic Data ◽  
Isotopic Study ◽  
Metasedimentary Rocks ◽  
The North ◽  
Wide Range ◽  
Western Block

AbstractTwo types of metasedimentary rocks occur in the Trans-North China Orogen of the North China Craton. One type consists of highly metamorphosed supracrustal rocks with protoliths of mature cratonic shale, called khondalites, as found in the Lüliang Complex; rocks of the other type are also highly metamorphosed but less mature, as represented by the Wanzi supracrustal assemblage in the Fuping Complex. U–Pb isotopic data for detrital zircons from khondalites show a provenance dominated by 1.9–2.1 Ga Palaeoproterozoic rocks. These detrital zircons display a wide range of εHfvalues from −16.0 to +9.2 and give Hf isotopic model ages mostly around 2.3 Ga. The high positive εHfvalues approach those for the depleted mantle at 2.1 Ga, highlighting a juvenile crustal growth event in Palaeoproterozoic times. Hf isotopic data also imply thatc.2.6 Ga old crustal material was involved in the Palaeoproterozoic magmatic event. These data are similar to those for the khondalitic rocks from the interior of the Western Block of the North China Craton, suggesting a common provenance. In contrast, other metasedimentary rocks in the Trans-North China Orogen, such as the Wanzi supracrustal assemblage in the Fuping Complex, have a source region with both Palaeoproterozoic and Archaean rocks. Their detrital zircon Hf isotopic data indicate reworking of old crustal material and a lack of significant juvenile Palaeoproterozoic magmatic input. These rocks are similar to the coevally deposited meta-sedimentary rocks in the interior of the Eastern Block. We propose that the Lüliang khondalites were deposited on the eastern margin of the Western Block in a passive continental margin environment and were thrust eastward later during collision with the Eastern Block. Other metasedimentary rocks in the Trans-North China Orogen were deposited on the western margin of the Eastern Block in a continental arc environment. Our data support the eastward subduction model for the Palaeoproterozoic tectonic evolution of the North China Craton.

Magmatic evolution of the southern Great Bear continental arc, northwestern Canadian Shield: geochronological constraints

2001 ◽  
Vol 38 (5) ◽  
pp. 767-785 ◽  
Author(s):  
S S Gandhi ◽  
J K Mortensen ◽  
N Prasad ◽  
O van Breemen
Keyword(s):  
Passive Margin ◽  
Calc Alkaline ◽  
Slave Craton ◽  
Continental Arc ◽  
Felsic Volcanism ◽  
Two Samples ◽  
Intrusive Rocks ◽  
Geochronological Constraints ◽  
Age Range ◽  
Age Constraints

The calc-alkaline Great Bear continental arc in the Wopmay Orogen developed after a collision ca. 1890 Ma of the Archean Slave craton with the Paleoproterozoic Hottah terrane to the west. U–Pb zircon dating of three volcanic and six intrusive rocks from the southern part of the arc shows four stages of development: (i) intrusion of a few small sodic leucogranite plutons at 1873 ± 2 Ma into a previously folded metasedimentary sequence; (ii) abundant calc-alkaline felsic volcanism and subvolcanic intrusions during the period 1870–1866 Ma, bracketed by five ages; (iii) intrusion of large calc-alkaline granitic plutons, including the Marian River batholith, dated by zircon and titanite from two samples at 1866 +2–3 Ma; and (iv) emplacement of the potassic Faber Lake rapakivi granite at 1856 +2–3 Ma. The arc was developed on the Hottah terrane due to easterly subduction of an oceanic plate under the amalgamated Slave craton – Hottah terrane. The oldest exposed rocks in the southern part of the arc are remnants of a Paleoproterozoic platformal sequence. They were regarded previously as equivalents of the initial passive margin sequence on the Slave craton, but are interpreted here as part of the Hottah terrane. The ages reported here are comparable with earlier data from the northern part of the arc, which show an age range from 1875 to 1840 Ma and also identify two suites of compositionally and temporally distinct granites. The age constraints show that the Great Bear arc evolved rapidly in time from sodic through calc-alkaline, and then, with a pause, to potassic composition.

New geochronologic and paleomagnetic results from early Neoproterozoic mafic sills and late Mesoproterozoic to early Neoproterozoic successions in the eastern North China Craton, and implications for the reconstruction of Rodinia

2019 ◽  
Vol 132 (3-4) ◽  
pp. 739-766 ◽  
Author(s):  
Hanqing Zhao ◽  
Shihong Zhang ◽  
Jikai Ding ◽  
Linxi Chang ◽  
Qiang Ren ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Critical Time ◽  
Middle Part ◽  
Detrital Zircons ◽  
Significant Discrepancy ◽  
Virtual Geomagnetic Pole ◽  
Geological Evidence ◽  
The North ◽  
Early Neoproterozoic

Abstract The interval from the late Mesoproterozoic to early Neoproterozoic is generally considered as a critical time for the amalgamation of Rodinia. The location of the North China Craton (NCC) in Rodinia remains contentious and demands greater paleomagnetic constraints. A combined geochronologic and paleomagnetic study was conducted on the late Mesoproterozoic to early Neoproterozoic rocks in the eastern NCC. Three sills were dated at ca. 945 Ma and one at ca. 920 Ma through use of the zircon U-Pb secondary ion mass spectroscopy method. Paleomagnetic investigation revealed no significant discrepancy between these sills. A positive baked-contact test, secular variation test and presence of reversals together support the primary origin interpretation for the remnant magnetization. A high-quality pole at (28.2 °S, 141.9 °E, A95 = 10.4°) was thus obtained by averaging our new results and a virtual geomagnetic pole previously reported for a ca. 920 Ma sill in the region. These Neoproterozoic sills intruded the successions that contain correlative strata that are named Nanfen, Xinxing, and Liulaobei formations in Liaoning, Jiangsu, and Anhui provinces, respectively. The Nanfen Formation and its equivalents are constrained between ca. 1120 and ca. 945 Ma by detrital zircons and the well-dated mafic sills. The paleomagnetic inclinations observed from the lower parts of the Nanfen, Xinxing, and Liulaobei formations are notably steep. The corresponding poles from these rock units are consistent and averaged at 38.6 °N, 136.7 °E (A95 = 3.2°). The quality of this pole is strengthened by a positive reversal test and its distinctiveness from the younger poles of the NCC. In the middle part of the Nanfen Formation, however, the paleomagnetic directions are characterized by moderate inclinations, being significantly different from those in the lower part of the Nanfen Formation and its equivalents. The calculated pole for the upper part of the Lower Member of the Nanfen Formation is at 8.0 °N, 128.5 °E (A95 = 7.9°). Another pole obtained from the Middle Member of the Nanfen Formation is at 11.2 °S, 127.7 °E (A95 = 8.5°). These two poles also differ from the younger poles of the NCC and likely represent the primary remanences. Our new results, together with the existing global paleomagnetic data and geological evidence, aided by the “right-way-up” connection model between Laurentia and Baltica in Rodinia, support a NCC–NW Laurentia connection between ca. 1120 and 890 Ma.

Episodic, mafic crust formation from 4.5 to 2.8 Ga: New evidence from detrital zircons, Slave craton, Canada

Geology ◽  
2008 ◽  
Vol 36 (11) ◽  
pp. 875 ◽  
Author(s):  
A.B. Pietranik ◽  
C.J. Hawkesworth ◽  
C.D. Storey ◽  
A.I.S. Kemp ◽  
K.N. Sircombe ◽  
...  
Keyword(s):  
Detrital Zircons ◽  
Crust Formation ◽  
Slave Craton ◽  
New Evidence

Preliminary results of the study on the reasons of the Hai Hau erosion phenomenon

2007 ◽  
Vol 29 (3) ◽  
pp. 415-426
Author(s):  
Pham Van Ninh ◽  
Phan Ngoc Vinh ◽  
Nguyen Manh Hung ◽  
Dinh Van Manh
Keyword(s):  
Mathematical Modeling ◽  
Historical Data ◽  
Middle Part ◽  
Red River ◽  
Erosion Process ◽  
Red River Delta ◽  
The North ◽  
Severe Erosion ◽  
North And South ◽  
Very High

Overall the evolution process of the Red River Delta based on the maps and historical data resulted in a fact that before the 20th century all the Nam Dinh coastline was attributed to accumulation. Then started the erosion process at Xuan Thuydistrict and from the period of 1935 - 1965 the most severe erosion was contributed in the stretch from Ha Lan to Hai Trieu, 1965 - 1990 in Hai Chinh - Hai Hoa, 1990 - 2005 in the middle part of Hai Chinh - Hai Thinh (Hai Hau district). The adjoining stretches were suffered from not severe erosion. At the same time, the Ba Lat mouth is advanced to the sea and to the North and South direction by the time with a very high rate.The first task of the mathematical modeling of coastal line evolution of Hai Hau is to evaluate this important historical marked periods e. g. to model the coastal line at the periods before 1900, 1935 - 1965; 1965 - 1990; 1990 - 2005. The tasks is very complicated and time and working labors consuming.In the paper, the primarily results of the above mentioned simulations (as waves, currents, sediments transports and bottom - coastal lines evolution) has been shown. Based on the obtained results, there is a strong correlation between the protrusion magnitude and the southward moving of the erosion areas.

INCORPORATION OF METASEDIMENTARY UNITS INTO THE DEEPEST EXPOSED LEVELS OF THE NORTH CASCADES CONTINENTAL ARC: COMPARISON OF THE SKAGIT AND SWAKANE GNEISSES

2017 ◽  
Author(s):  
Kirsten B. Sauer ◽  
◽  
Stacia M. Gordon ◽  
Robert B. Miller ◽  
Jeffrey Vervoort ◽  
...  
Keyword(s):  
North Cascades ◽  
The North ◽  
Continental Arc
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