Thermochronological constraints on the Eocene exhumation of the Grand Forks complex, British Columbia, based on 40Ar/39Ar and apatite fission track geochronology

2013 ◽  
Vol 50 (5) ◽  
pp. 576-598 ◽  
Author(s):  
J.F. Cubley ◽  
D.R.M. Pattison ◽  
D.A. Archibald ◽  
M. Jolivet
Keyword(s):  
Fission Track ◽  
Hanging Wall ◽  
Closure Temperature ◽  
Normal Faults ◽  
Low Grade ◽  
Early Eocene ◽  
Apatite Fission Track ◽  
Slow Cooling ◽  
Rapid Phase ◽  
Grand Forks

The Grand Forks complex (GFC) is a metamorphic core complex within the composite Shuswap complex in the southern Omineca belt of the Canadian Cordillera. It is juxtaposed against the surrounding low-grade rocks of the pericratonic Quesnel terrane by outward-dipping Eocene normal faults. The GFC attained peak metamorphic conditions of 750–800 °C and 5.5–6.0 kbar (1 kbar = 100 MPa) in the late Paleocene to early Eocene, followed by ∼2.5 kbar of near-isothermal decompression at upper-amphibolite to granulite facies conditions (∼725–750 °C) in the early Eocene. Subsequent low-temperature greenschist-facies exhumation (∼0.7–1.5 kbar) was accommodated by the brittle–ductile Kettle River normal fault (KRF) on the east flank of the complex and the Granby fault (GF) on the west flank. This study presents 16 new 40Ar/39Ar hornblende and biotite dates from the GFC and low-grade rocks in the hanging walls to the KRF and GF. Cooling of the GFC through the closure temperature of hornblende (∼ 530 °C) is constrained to the interval between ∼54 and 51.4 ± 0.5 Ma, whereas cooling through the closure temperature of biotite (∼280 °C) occurred at 51.4 ± 0.2 Ma. In the hanging wall of the KRF, cooling through the closure temperature of hornblende and biotite occurred nearly coevally at 51.7 ± 0.6 Ma and 51.0 ± 1.0 Ma, respectively. Five apatite fission track dates (closure temperature ∼110 °C) from the GFC and adjacent hanging walls are indistinguishable within error, yielding an average age of 34.6 ± 2.0 Ma. The lack of difference in biotite and apatite ages between the GFC and the low-grade hanging wall rocks against which it is juxtaposed suggests no significant movement on the KRF and GF after ca. 51 Ma. Results from this study and a previous study on U–Pb dating of the GFC document rapid cooling of the GFC in excess of 200 °C/Ma in a 4 Ma interval between 55 and 51 Ma (Eocene). This rapid phase of exhumation of the GFC was followed by 15 Ma of slow cooling (∼10 °C/Ma) of the joined GFC and hanging wall between ∼280 °C (biotite closure) and ∼110 °C (apatite closure).

Late Miocene thermal history of the Hengchun Peninsula, Southern Taiwan: Apatite Fission-Track data from the Lilungshan Formation

2020 ◽  
Author(s):  
Shao-I Kao ◽  
Wen-Shan Chen ◽  
Tong Hin Chan
Keyword(s):  
Low Temperature ◽  
Late Miocene ◽  
Thermal History ◽  
Fission Track ◽  
Closure Temperature ◽  
Radiometric Dating ◽  
Low Grade ◽  
Apatite Fission Track ◽  
Fission Tracks ◽  
Southern Taiwan

<p>This study aims to investigate the thermal history regarding the Late Miocene Formation of the Hengchun Peninsula with low-temperature thermal chronometry. The samples used in our study were from Lilungshan Formation, which included quartzite (conglomerates) and sandstones (matrix). Lilungshan Formation was an upper fan or feeder channel deposits in shelf environments. Measurements of paleocurrent indicate that these rocks were transported from the NW to the SE, which may represent its source area is a low-grade metamorphic orogenic belt (Yuli belt). In the Late Miocene, outcrops of Yuli belt were low-grade metamorphic rocks with low metamorphic temperatures. To do so, low-temperature thermal chronometry was applied to measure the time since the Lilungshan Formation cooling below the closure temperature. Apatite Fission-track thermochronology is used in this study, which is a radiometric dating method that refers to thermal histories of rocks within the closure temperature range of 110–135°C.</p><p>Our study indicates that the pooled age of apatite fission tracks of conglomerates is 3.3–5 Ma and the grain ages of sandstones are below 5 Ma. Those ages are lower than the formation age of Lilungshan Formation (NN11, > 5.6 Ma). In addition, the grain ages spectrum of sandstones is partial annealing, which implies that the conglomerate has suffered from the thermal event and rapidly brought to the earth’s surface within 4 Ma. This study also compares data of previous studies with regard to the fission tracks of conglomerates in Southern Taiwan and confirms the existence of thermal events. With the assumption that the thermal gradient of the accretionary prism is 40–45°C/km, we can suggest that Lilungshan Formation was located 3 km below the earth's surface in roughly 4 Ma.</p><p> </p><p><strong>Keywords: </strong>Hengchun Peninsula, Lilungshan Formation, Apatite Fission Track, thermal history, chronometry, Late Miocene</p>

scholarly journals Thermal evolution of the Malá Fatra Mountains (Central Western Carpathians): insights from zircon and apatite fission track thermochronology

2010 ◽  
Vol 61 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Martin Danišík ◽  
Milan Kohút ◽  
Igor Broska ◽  
Wolfgang Frisch
Keyword(s):  
Fission Track ◽  
Thermal Evolution ◽  
Western Carpathians ◽  
Low Grade ◽  
Apatite Fission Track ◽  
Metamorphic Overprint ◽  
Fission Track Thermochronology ◽  
Fast Cooling ◽  
Central Western Carpathians ◽  
Early Late

Thermal evolution of the Malá Fatra Mountains (Central Western Carpathians): insights from zircon and apatite fission track thermochronologyWe apply zircon and apatite fission track thermochronology (ZFT and AFT, respectively) to the Variscan crystal-line basement of the Malá Fatra Mts (Central Western Carpathians) in order to constrain the thermal history. The samples yielded three Early Cretaceous ZFT ages (143.7±9.6, 143.7±8.3, 135.3±6.9 Ma) and one Eocene age (45.2±2.1 Ma), proving that the basement was affected by a very low-grade Alpine metamorphic overprint. Although the precise timing and mechanisms of the overprint cannot be unequivocally resolved, we propose and discuss three alternative explanations: (i) a Jurassic/Cretaceous thermal event related to elevated heat flow associated with extensional tectonics, (ii) early Late Cretaceous thrusting and/or (iii) an Eocene orogeny. Thermal modelling of the AFT cooling ages (13.8±1.4 to 9.6±0.6 Ma) revealed fast cooling through the apatite partial annealing zone. The cooling is interpreted in terms of exhumation of the basement and creation of topographic relief, as corroborated by the sedimentary record in the surrounding Neogene depressions. Our AFT results significantly refine a general exhumation pattern of basement complexes in the Central Western Carpathians. A younging of AFT ages towards the orogenic front is evident, where all the external massifs located closest to the orogenic front (including Malá Fatra Mts) were exhumed after ~13 Ma from temperatures above ~120 °C.

scholarly journals Eocene exhumation and extensional basin formation in the Copper Mountains, Nevada, USA

Geosphere ◽  
2019 ◽  
Vol 15 (5) ◽  
pp. 1577-1597
Author(s):  
Andrew S. Canada ◽  
Elizabeth J. Cassel ◽  
Allen J. McGrew ◽  
M. Elliot Smith ◽  
Daniel F. Stockli ◽  
...  
Keyword(s):  
Hanging Wall ◽  
Normal Fault ◽  
High Elevation ◽  
Late Eocene ◽  
Closure Temperature ◽  
Coarse Grained ◽  
Normal Faults ◽  
Extensional Deformation ◽  
Early Oligocene ◽  
Basin Formation

Abstract Within extended orogens, records that reflect the driving processes and dynamics of early extension are often overprinted by subsequent orogenic collapse. The Copper Mountains of northeastern Nevada preserve an exceptional record of hinterland extensional deformation and high-elevation basin formation, but current geochronology and thermochronology are insufficient to relate this to broader structural trends in the region. This extension occurred concurrent with volcanism commonly attributed to Farallon slab removal. We combine thermochronology of both synextensional hanging-wall strata and footwall rocks to comprehensively evaluate the precise timing and style of this deformation. Specifically, we apply (U-Th)/(He-Pb) double dating of minerals extracted from Eocene–Oligocene Copper Basin strata with multi-mineral (U-Th)/He and 40Ar/39Ar thermochronology of rocks sampled across an ∼20 km transect of the Copper Mountains. We integrate basement and detrital thermochronology records to comprehensively evaluate the timing and rates of hinterland extension and basin sedimentation. Cooling and U-Pb crystallization ages show the Coffeepot Stock, which spans the width of the Copper Mountains, was emplaced at ca. 109–108 Ma, and then cooled through the 40Ar/39Ar muscovite and biotite closure temperatures by ca. 90 Ma, the zircon (U-Th)/He closure temperature between ca. 90 and 70 Ma, and the apatite (U-Th)/He closure temperature between 43 and 40 Ma. Detrital apatite and zircon (U-Th)/(He-Pb) double dating of late Eocene fluvial and lacustrine strata of the Dead Horse Formation and early Oligocene fluvial strata of the Meadow Fork Formation, both deposited in Copper Basin, shows that Early Cretaceous age detrital grains have a cooling history that is analogous to proximal intrusive rocks of the Coffeepot Stock. At ca. 38 Ma, cooling and depositional ages for Copper Basin strata reveal rapid exhumation of proximal source terranes (cooling rate of ∼37 °C/m.y.); in these terranes, 8–12 km of slip along the low-angle Copper Creek normal fault exhumed the Coffeepot Stock in the footwall. Late Eocene–early Oligocene slip along this fault and an upper fault splay, the Meadow Fork fault, created a half graben that accommodated ∼1.4 km of volcaniclastic strata, including ∼20 m of lacustrine strata that preserve the renowned Copper Basin flora. Single-crystal sanidine 40Ar/39Ar geochronology of interbedded tuffs in Copper Basin constrains the onset of rapid exhumation to 38.0 ± 0.9 Ma, indicating that surface-breaching extensional deformation was coincident with intense proximal volcanism. Coarse-grained syndeformational sediments of the Oligocene Meadow Fork Formation were deposited just prior to formation of an extensive regional Oligocene–Miocene unconformity and represent one of the most complete hinterland stratigraphic records of this time. We interpret this history of rapid late Eocene exhumation across the Copper Mountains, coeval volcanism, and subsequent unconformity formation to reflect dynamic and thermal effects associated with Farallon slab removal. The final phase of extension is recorded by late, high-angle normal faults that cut and rotate the early middle Miocene Jarbidge Rhyolite sequence, deposited unconformably in the hanging wall. These results provide an independent record of episodic Paleogene to Miocene exhumation documented in Cordilleran metamorphic core complexes and establish that substantial extension occurred locally in the hinterland prior to province-wide Miocene extensional break-up.

scholarly journals The thermal history of the Miocene Ibar Basin (Southern Serbia): new constraints from apatite and zircon fission track and vitrinite reflectance data

2015 ◽  
Vol 66 (1) ◽  
pp. 37-50 ◽  
Author(s):  
Nevena Andrić ◽  
Bernhard Fügenschuh ◽  
Dragana Životić ◽  
Vladica Cvetković
Keyword(s):  
Thermal History ◽  
Large Scale ◽  
Fission Track ◽  
Vitrinite Reflectance ◽  
Hanging Wall ◽  
Time Frame ◽  
Apatite Fission Track ◽  
Basin Inversion ◽  
Zircon Fission Track ◽  
Maximum Temperatures

Abstract The Ibar Basin was formed during Miocene large scale extension in the NE Dinaride segment of the Alpine- Carpathian-Dinaride system. The Miocene extension led to exhumation of deep seated core-complexes (e.g. Studenica and Kopaonik core-complex) as well as to the formation of extensional basins in the hanging wall (Ibar Basin). Sediments of the Ibar Basin were studied by apatite and zircon fission track and vitrinite reflectance in order to define thermal events during basin evolution. Vitrinite reflectance (VR) data (0.63-0.90 %Rr) indicate a bituminous stage for the organic matter that experienced maximal temperatures of around 120-130 °C. Zircon fission track (ZFT) ages indicate provenance ages. The apatite fission track (AFT) single grain ages (45-6.7 Ma) and bimodal track lengths distribution indicate partial annealing of the detrital apatites. Both vitrinite reflectance and apatite fission track data of the studied sediments imply post-depositional thermal overprint in the Ibar Basin. Thermal history models of the detritial apatites reveal a heating episode prior to cooling that began at around 10 Ma. The heating episode started around 17 Ma and lasted 10-8 Ma reaching the maximum temperatures between 100-130 °C. We correlate this event with the domal uplift of the Studenica and Kopaonik cores where heat was transferred from the rising warm footwall to the adjacent colder hanging wall. The cooling episode is related to basin inversion and erosion. The apatite fission track data indicate local thermal perturbations, detected in the SE part of the Ibar basin (Piskanja deposit) with the time frame ~7.1 Ma, which may correspond to the youngest volcanic phase in the region.

Burial and exhumation of the Long Range Inlier and its surroundings, western Newfoundland: results of an apatite fission-track study

1993 ◽  
Vol 30 (8) ◽  
pp. 1594-1606 ◽  
Author(s):  
M. Hendriks ◽  
R. A. Jamieson ◽  
S. D. Willett ◽  
M. Zentilli
Keyword(s):  
Long Range ◽  
Fission Track ◽  
Sedimentary Cover ◽  
Early Carboniferous ◽  
Track Length ◽  
Lake Basin ◽  
Apatite Fission Track ◽  
Slow Cooling ◽  
Base Level ◽  
Thermal Histories

The Long Range Inlier, a steep-sided plateau underlain mainly by Grenvillian gneisses, is the most prominent topographic feature of western Newfoundland. Apatite fission-track analysis of 31 samples from the Long Range Inlier and its surroundings yielded measured apparent ages of 343–152 Ma. Age versus elevation plots, track-length distributions, and model thermal histories indicate that the region experienced slow cooling in the late Paleozoic, with apparent exhumation rates of 7–9 m∙Ma−1 and cooling rates of 0.08–0.28 °C∙Ma−1. Model thermal histories suggest that the present upper surface of the Long Range plateau cooled below ~120 °C in Ordovician times. The thermal histories are compatible with, but do not require, some exhumation of the Long Range Inlier along Acadian thrust faults. Results from Early Carboniferous sedimentary rocks of the Deer Lake Basin are similar to Long Range Inlier data from similar elevations, implying that at some time between ~350 and 300 Ma, the entire region was buried to depths sufficient to induce total annealing (T > 120 °C) in these samples. Closure ages determined from model thermal histories indicate that regional cooling to temperatures below ~120 °C began before 300 Ma. The Carboniferous sedimentary cover was largely removed by Jurassic time, perhaps in response to lowering of regional base level by rifting associated with the opening of the Atlantic Ocean.

Bivergent extension in the overriding plate above a slab tear (Dodecanese, Greece)

2020 ◽  
Author(s):  
Bernhard Grasemann ◽  
David A. Schneider ◽  
Konstantinos Soukis ◽  
Vincent Roche
Keyword(s):  
Eastern Mediterranean ◽  
Hanging Wall ◽  
Finite Extension ◽  
Normal Fault ◽  
Vertical Axis ◽  
Normal Faults ◽  
Low Grade ◽  
Thrust Belt ◽  
Fold And Thrust Belt ◽  
Variscan Basement

<p><span lang="EN-US">Tearing in the Hellenic slab below the transition between the Aegean and Anatolian plate is considered to have significantly affected Miocene tectonic and magmatic evolution of the eastern Mediterranean by causing a toroidal flow of asthenosphere and a lateral gradient of extension in the upper plate. Some studies suggest that this lateral gradient is accommodated by a distributed sinistral lithospheric-scale shear zone whereas other studies favor a localized NE-SW striking transfer zone. Recent studies in the northern Dodecanese demonstrate that the transition zone between the Aegean and Anatolian plate is characterized by Miocene extension with a constant NNE-SSW sense of shear accommodating the difference in finite extension rates in the middle-lower crust. Neither localized or distributed strike-slip faults nor rotation of blocks about a vertical axis have been observed.</span></p> <p><span lang="EN-US">In this work we focus on the geology Kalymnos located in the central Dodecanese. Based on our new geological map, three major tectonic units can be distinguished: (i) Low-grade, fossil-rich late Paleozoic marbles, which have been deformed into S-vergent folds and out-of-sequence thrusts. This fold-and-thrust belt is sealed by an up to 200 m thick wildflysch-type deposit consisting of low-grade metamorphic radiolarites and conglomerates with tens of meters-scale marbles and ultramafics blocks. (ii) Above this unit, amphibolite facies schists, quartzites and amphibolites are tectonically juxtaposed along a several meter-thick thrust fault with low-grade ultramylonites and cohesive ultracataclasites/pseudotachylites with top-to-N kinematics. (iii) At highest structural levels, a major cataclastic low-angle normal fault zone localized in Verrucano-type violet slates separates Mesozoic unmetamorphosed limestones in the hanging wall. The sense of shear of the normal fault is top-to-SSW. All units are cut by brittle high-angle normal faults shaping the geomorphology of Kalymnos, which is characterized by three major NNW-SSE trending graben systems.</span></p> <p><span lang="EN-US">New white mica Ar-Ar ages suggests that the middle units represent relics of a Variscan basement, which was thrusted on top of a fold-and-thrust belt during an Eo-Cimmerian event. Zircon (U-Th)/He ages from the Variscan basement are c. 28 Ma, indicating that the lower units were exhumed below the Mesozoic carbonates during the Oligocene-Miocene. Since Miocene extension in the northern Dodecanese records top-to-NNE kinematics, we suggest that back-arc extension in the whole Aegean realm and transition to the Anatolian plate is bivergent, and tearing in the Hellenic slab did not significantly affected the extension pattern in the upper crust.</span></p>

scholarly journals Evidence for post-early Eocene tectonic activity in southeastern Ireland

2003 ◽  
Vol 140 (2) ◽  
pp. 101-118 ◽  
Author(s):  
M. J. M. CUNNINGHAM ◽  
A. L. DENSMORE ◽  
P. A. ALLEN ◽  
W. E. A. PHILLIPS ◽  
S. D. BENNETT ◽  
...  
Keyword(s):  
Fission Track ◽  
Tectonic Activity ◽  
Early Eocene ◽  
Apatite Fission Track ◽  
Annealing Zone ◽  
Domain Boundaries ◽  
Vertical Displacements ◽  
Spatial Domains ◽  
Thermal Histories ◽  
Partial Annealing

The role played by Cenozoic deformation in denudation and landscape development in Ireland has historically been difficult to assess because of the lack of widespread pre-glacial Cenozoic deposits onshore. Here we combine analysis of apatite fission-track data and geomorphic observations to place constraints on the timing, kinematics and magnitude of onshore deformation in southeastern Ireland. Relationships between apatite fission-track central age and elevation for samples from the Wicklow and Blackstairs Mountains and Tullow Lowland suggest that these rocks record an exhumed apatite partial annealing zone, which after cooling was dismembered by differential vertical displacements of up to several hundred metres. We use inverted models of sample thermal history to show that samples across the region experienced very similar thermal histories up to and including a cooling event in late Paleocene or early Eocene time. This effectively rules out strongly spatially heterogeneous denudation, and implies that differential rock uplift occurred in post-early Eocene time. The central age–elevation relationships define at least three spatial domains with internally consistent apatite fission-track data, separated by known faults or topographic escarpments. Geomorphic analysis of these structures shows that patterns of catchment incision and sinuosity, as well as the presence of antecedent drainage, are best explained by differential vertical displacements at or near the domain boundaries. The kinematics and magnitudes of these displacements are consistent with those implied by the apatite fission-track results, and are compatible with other examples of known Cenozoic deformation from Ireland and the adjacent continental margin.

scholarly journals Spilitization of Early-Permian Volcanics from Głuszyca Górna (the Intra-Sudetic Basin, Poland)—Constraints from Chlorite Thermometry Coupled with Apatite Fission-Track Dating (AFT)

2021 ◽  
Vol 6 (1) ◽  
pp. 3
Author(s):  
Tomasz Powolny ◽  
Aneta Anczkiewicz ◽  
Dumańska-Słowik Magdalena
Keyword(s):  
Fission Track ◽  
Volcanic Rocks ◽  
Volcanic Glass ◽  
Early Permian ◽  
Fission Track Dating ◽  
Apatite Fission Track ◽  
Slow Cooling ◽  
Late Mesozoic ◽  
Compositional Variations ◽  
Apatite Fission Track Dating

The Intra-Sudetic Basin, a Late-Paleozoic intramontane trough located on the NE flank of the Bohemian Massif, is comprised of numerous outcrops of continental (extension-related) Early-Permian volcanogenic rocks that are commonly altered to spilites. In this contribution, we provide insights into the formation of spilitized (albite- and chlorite-rich) trachyandesites from the Głuszyca quarry (Lower Silesia, Poland), based on mineralogical and micro-textural investigations supported by apatite fission-track dating (AFT). Our results indicate that the trachyandesites, emplaced as a shallow-level laccolith-type body, have been strongly affected by chloritization of both aegirine and augite, combined with an occasional celadonitization of volcanic glass. Furthermore, chlortitization of sodic pyroxenes must have released notable amounts of Na+, which could be involved during later pervasive albitzation of primary andesine-labradorite. According to various chemical and semi-empirical thermometers, the replacive chlorites formed in the range of 124–170 °C. Trachyandesites from Głuszyca contain abundant fluorapatites, marked by the occurrence of swallow-type terminations, which are indicative of rapid-cooling formation conditions. Central AFT ages of the samples vary between 161–182 Ma and correspond to the Middle-Jurassic period. Meanwhile, these ages are significantly younger than the emplacement of igneous rocks during the Middle-Rotliegendes period (~299–271 Ma). The discrepancy between the stratigraphic age of the rocks and the AFT results cannot be, however, explained by, for example, slow cooling rates of magmatic body, compositional variations of apatite, or burial under Late-Mesozoic sediments. Hence, it may be assumed that the obtained AFT ages (161–182 Ma) reflect the timing of spilitization and associated partial reheating of volcanic rocks from the Intra-Sudetic Basin above the apatite partial annealing zone (70–110 °C).

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