Thermochronologic constraints on ore formation at the Gays River Pb–Zn deposit, Nova Scotia, Canada, from apatite fission track analysis

1990 ◽  
Vol 27 (8) ◽  
pp. 1013-1022 ◽  
Author(s):  
Dennis C. Arne ◽  
Ian R. Duddy ◽  
Don F. Sangster
Keyword(s):  
Nova Scotia ◽  
Fission Track ◽  
Track Length ◽  
Late Paleozoic ◽  
Apatite Fission Track ◽  
Ore Formation ◽  
Sulphide Mineralization ◽  
Fission Track Ages ◽  
Uplift And Erosion ◽  
Host Rocks

Fission tracks in detrital apatites from the Cambro-Ordovician metasedimentary basement in the vicinity of the Carboniferous-hosted Gays River Pb–Zn deposit, Nova Scotia, provide a record of final cooling during uplift and erosion of the Meguma Zone and constrain the timing of ore formation. Apatite fission track ages range from 203 to 241 Ma, with typical uncertainties of ± 10 Ma. Mean confined track lengths generally vary between 12.0 and 13.4 μm and indicate that the apatites record "apparent" ages only. An inferred thermal history involving regional heating to paleotemperatures > 110 °C during late Paleozoic burial followed by cooling to ~ 110 °C prior to 240–220 Ma is suggested. A more recent phase or regional heating to paleotem-peratures probably in the range of 60–80 °C during Late Cretaceous – early Tertiary (ca. 100–50 Ma) burial is also indicated by the track length data. Apatite fission track ages and mean track lengths from drill-core samples immediately beneath the Gays River orebody are similar to those for regional outcrop samples. At minimum temperatures > 200 °C estimated for ore formation, sulphide mineralization must either have preceded or accompanied regional heating to paleotemperatures > 110 °C during the late Paleozoic. Sulphide mineralization at Gays River must therefore have taken place at some time after ca. 330 Ma (the stratigraphic age of the lower Windsor Group host rocks) but before ca. 240–220 Ma (the last cooling of Meguma Group basement below 110 °C). These constraints on the timing of ore formation at Gays River are compatible with previous suggestions that Pb–Zn mineralization of Carboniferous strata in Nova Scotia occurred at ca. 300 Ma.

The Scotian Basin offshore Nova Scotia: thermal history and provenance of sandstones from apatite fission track and 40Ar/39Ar data

1992 ◽  
Vol 29 (5) ◽  
pp. 909-924 ◽  
Author(s):  
A. M. Grist ◽  
P. H. Reynolds ◽  
M. Zentilli ◽  
C. Beaumont
Keyword(s):  
Nova Scotia ◽  
Thermal History ◽  
Fission Track ◽  
Vitrinite Reflectance ◽  
Source Rocks ◽  
Apatite Fission Track ◽  
Eastern Canada ◽  
Grenville Province ◽  
Thermal Indicators ◽  
Fission Track Ages

Apatite fission track and 40Ar/39Ar age spectrum data from sandstone drill-core minerals taken from depths of 2–5 km in nine wells from the Scotian Basin are presented and interpreted in terms of the thermal history of the basin and the provenance of its sediments. The focus of the study is a comparison of the data from these thermochronometers with each other and with previously published vitrinite reflectance and aromatization–isomerization (A–I) reactions in biomarker compounds from the same or nearby wells.Apatite fission track ages are generally in agreement with expectations in that they trend to zero at a depth of ~4 km (corrected bottom-hole temperature ~120 °C). Shallower (lower present temperature) samples are partially annealed; the degree of partial annealing correlates closely with the degree of A–I reactions. Both thermal indicators are activated over the temperature range 60–120 °C.Samples from two wells, Mic Mac J-77 and Erie D-26, are anomalous. They are more annealed than present formation temperatures would predict, an anomaly that is also indicated by the A–I data. These samples are interpreted as having experienced higher than present temperatures subsequent to deposition, possibly resulting from the passage of hot fluids related to localized volcanism or the sudden venting of an overpressured reservoir.K-feldspars record minor (< 20%) argon loss as a result of burial heating in the basin only at the greatest depths of the sampled range (> 4.3 km). This result is in agreement with the thermal models of the Scotian Basin and extrapolation of the A–I and fission track data to greater depths. The inferred argon loss implies an activation energy of 40 ± 4 kcal/mol for the smallest diffusion domains.The argon age spectra for samples that have not lost argon during residence in the basin provide evidence on the provenance of the sediments. K-feldspars from the Early Cretaceous Missisauga Formation have spectra that are similar to those obtained from K-feldspars from the Grenville Province of the Canadian Shield, whereas muscovites from the same formation give Cambrian to Carboniferous argon ages (mean 387 Ma), an indication of contributions from other source rocks. Corresponding data from the Jurassic Mohican Formation are similar to those reported for plutons from the southern Nova Scotia mainland (ca. 250–350 Ma argon ages). By implication, the Mohican Formation, which is the earliest postrift deposit, was derived from local sources inferred to be adjacent flank uplifts, whereas the Missisauga Formation was derived in part either directly or indirectly from the Grenvillian-aged interior of eastern Canada.

The Miocene plutonic event of the Patagonian Batholith at 44° 30′ S: thermochronological and geobarometric evidence for melting of a rapidly exhumed lower crust

2000 ◽  
Vol 91 (1-2) ◽  
pp. 169-179 ◽  
Author(s):  
M. A. Parada ◽  
A. Lahsen ◽  
C. Palacios
Keyword(s):  
Late Miocene ◽  
Lower Crust ◽  
Fission Track ◽  
Strike Slip ◽  
Fault System ◽  
Apatite Fission Track ◽  
Axial Zone ◽  
Exhumation Rates ◽  
Fission Track Ages ◽  
Host Rocks

The Patagonian Batholith was formed by numerous plutonic events that took place between the Jurassic and the Miocene. North of 47° S, the youngest plutons occupy the axial zone adjacent to the Liquiñe-Ofqui Fault Zone, which is a major intra-arc strike-slip fault system active since the Miocene. The Queulat Complex, located at 44° 30′ S, includes two Miocene plutonic units: the Early Miocene Queulat diorite (QD) and the Late Miocene Puerto Cisnes granite (PCG). The QD includes hornblende + clinopyroxene diorites and tonalites, whereas the PCG includes slightly peraluminous garnet ± sillimanite granites and granodiorites.Eleven mineral Ar–Ar ages and three apatite fission track ages were obtained from the Queulat Complex and surrounding host rocks. Hornblende and biotite Ar–Ar ages of c. 16-18 Ma and 9-10 Ma, respectively, were obtained for the QD. The youngest ages of the QD are similar to the age of emplacement of the PCG as previously determined. Ar–Ar ages for muscovites and biotites of 6·6 ± 0·3 Ma and 5·6 ± 0·1 Ma, respectively, were obtained for the PCG. Biotites and muscovites from mylonites and pelitic hornfelses adjacent to the PCG yielded Ar—Ar ages between 5·1 Ma and 5·5 Ma. The apatite fission track ages of the QD and PCG overlap within the error margin (2•2 ± 1·1-3·3 ± 1·4 Ma).The Al-in-hornblende geobarometer yielded pressures for the QD emplacement equivalent to depths in the 19-24 km range, which is substantially higher than the 10 km depth estimated previously for the PCG emplacement. Exhumation rates (v) up to 2·0mm/yr were calculated for the time elapsed between the QD and PCG emplacements. A v value of 1·0mm/yr was calculated for the PCG subsequent to its emplacement. Using the silica—Ca-tschermak-anorthite geobarometer, we estimate the QD magma generation to be at c. 33 km, which is similar to the current crustal thickness. Melting of mafic and metapelitic lower crust was possible at > 30km depth during a period when v was between 1·0mm/yr and 2·0mm/yr.

scholarly journals CENOZOIC TECTONIC EVOLUTION OF THE EASTERN ALPS – A RECONSTRUCTION BASED ON 40AR/39AR WHITE MICA, ZIRCON AND APATITE FISSION TRACK, AND APATITE (U/Th)-He THERMOCHRONOLOGY

2017 ◽  
Vol 43 (1) ◽  
pp. 299
Author(s):  
W. Kurz ◽  
A. Wölfler ◽  
R. Handler
Keyword(s):  
Tectonic Evolution ◽  
Fission Track ◽  
Eastern Alps ◽  
White Mica ◽  
Fault Zones ◽  
Apatite Fission Track ◽  
Major Fault ◽  
Fission Track Ages ◽  
Fault Gouges ◽  
Host Rocks

The Cenozoic tectonic evolution of the Eastern Alps is defined by nappe assembly within the Penninic and Subpenninic units and their subsequent exhumation. The units above, however, are affected by extension and related faulting. By applying distinct thermochronological methods with closure temperatures ranging from ~450° to ~40°C we reveal the thermochronological evolution of the eastern part of the Eastern Alps. 40Ar/39Ar dating on white mica, zircon and apatite fission track, and apatite U/Th-He thermochronology were carried out within distinct tectonic units (Penninic vs. Austroalpine) and on host rocks and fault- related rocks (cataclasites and fault gouges) along major fault zones. We use particularly the ability of fission tracks to record the thermal history as a measure of heat transfer in fault zones, causing measurable changes of fission track ages and track lengths. Additionally, these studies will provide a general cooling and exhumation history of fault zones and adjacentcrustal blocks.

Thermal history modelling of the western margin of the Bohemian Massif using high-resolution apatite fission-track thermochronology

2020 ◽  
Author(s):  
Lucie Novakova ◽  
Raymond Jonckheere ◽  
Bastian Wauschkuhn ◽  
Lothar Ratchbacher
Keyword(s):  
High Resolution ◽  
Bohemian Massif ◽  
Thermal History ◽  
Fission Track ◽  
Track Length ◽  
Apatite Fission Track ◽  
Fission Track Thermochronology ◽  
Length Measurements ◽  
Thermal Histories ◽  
Fission Track Ages

&lt;p&gt;The Naab area is situated on the western border of the Bohemian Massif, 60 km south of the KTB (Kontinentalen Tiefbohrung). The main super-deep borehole of the KTB reached a depth of 9,101 meters in the Earth's continental crust. The fission-track data for the KTB and the Naab area present contrasting signatures. The apatite fission-track ages in the upper section of the KTB borehole and surrounding area are in the range 50-70 Ma (Wagner et al., 1994; Wauschkuhn et al., 2015). The apatite fission-track ages of the Naab basement are older than those of the KTB area, and span a broader range: 120-200 Ma (Vercoutere, 1994). The distributions of the confined-track lengths range from unimodal over skewed and mixed to bimodal, with mean lengths in the range 11-13 &amp;#181;m. In broad terms, this can be interpreted as that the Naab samples contain both an older and younger (in particular pre- and post-late Cretaceous) fission-track population. The aim of our research is to investigate the applicability of lab-based models to geological data, using improved measurement techniques.&lt;/p&gt;&lt;p&gt;We studied eighteen samples dated by Vercoutere (1994) from the Palaeozoic basement and seven large rock samples from the Rotliegend strata north of the Luhe fault.&amp;#160; We intend to extend the confined-track length measurements of Vercoutere (1994), aiming to achieve higher resolution through methodological innovations made possible by computer-controlled motorized microscopes. Improved statistics increase the resolution of the modelled thermal histories, which permits to better distinguish systematic from statistical differences between the modelled palaeotemperatures and geological estimates. Experiments have shown that the rate of length increase permits to distinguish older from younger tracks (Jonckheere et al., 2017). This allows us to distinguish between tracks formed before and after the Late Cre&amp;#173;taceous to Palaeocene exhumation. The etch rate of a confined track is also an indicator of its individual thermal history, supplementing the information gleaned from its etchable length under fixed conditions. We compiled a comprehensive, high-resolution confined-track-length dataset. The Naab thermal histories were determined using modern modelling algorithms, implementing the most recent empirical equations.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Jonckheere R., Tamer M., Wauschkuhn F., Wauschkuhn B., Ratschbacher L., 2017. Single-track length measurements of step-etched fission tracks in Durango apatite: Vorsprung durch Technik.American Mineralogist 102, 987-996.&lt;/p&gt;&lt;p&gt;Vercoutere C., 1994. The thermotectonic history of the Brabant Massif (Belgium) and the Naab Basement (Germany): &amp;#160;&amp;#160;an apatite fission track analysis. Ph. D. thesis, Universiteit Gent, pp. 191.&lt;/p&gt;&lt;p&gt;Wagner G.A., Hejl E., Van Den Haute P., 1994. The KTB fission-track project: Methodical aspects and geological implications. Radiation Measurements 23, 95-101.&lt;/p&gt;&lt;p&gt;Wauschkuhn B., Jonckheere R., Ratschbacher L., 2015. The KTB apatite fission-track profiles: building on a firm foundation? Geochimica et Cosmochimica Acta 167, 27-62.&lt;/p&gt;

On the thermo-tectonic evolution of Northern England: evidence from fission track analysis

1986 ◽  
Vol 123 (5) ◽  
pp. 493-506 ◽  
Author(s):  
Paul F. Green
Keyword(s):  
Elevated Temperatures ◽  
Fission Track ◽  
Apatite Fission Track ◽  
Fission Track Analysis ◽  
Track Record ◽  
Tectonic Events ◽  
Fission Track Ages ◽  
Uplift And Erosion ◽  
Unique Potential ◽  
Track Analysis

AbstractThe limited amount of fission track data previously available in Northern Britain has shown unexplained Cretaceous ages in the Southern Uplands and Lake District. Apatite fission track analysis has been applied to 23 samples from Caledonian intrusive bodies, to further investigate these ages. Fission track data of sphene has been carried out on seven samples and zircon in one sample.Apatite fission track ages vary from a maximum of 278 ± 12 Ma in the Cheviot Granite, down to ages of ∼ 60 Ma in the Carrock Fell region, with intermediate ages of ∼ 140 Ma in the Eskdale Granite and ∼ 80 Ma in the Shap Granite. This variation in fission track age is accompanied by changes in the distribution of confined fission track lengths. Samples with the youngest ages (∼ 60 Ma) have long, narrow distributions (mean length > 14 μm; standard deviation ∼ 1 μm) typical of samples which have had all pre-existing tracks erased by elevated temperatures, and subsequently cooled rapidly so that all tracks now observed have formed at low temperatures. As ages increased from 60 Ma, a component of shorter tracks becomes more dominant, representing tracks which have been shortened at elevated temperatures. Thus ages greater than 60 Ma are ‘apparent ages’, representing a partial overprint of a pre-existing track record, while the ∼ 60 Ma ages record a total resetting at this time.The heating responsible for the observed fission track annealing may be due to residence at temperatures in the range 70–125 °C over many tens of Ma, or to a short lived heat pulse perhaps associated with the Tertiary igneous province of the northwest. In either case, uplift and erosion on a scale of kilometres at ∼ 60 Ma ago is necessary to produce the observed pattern of fission track parameters. This uplift may be related in some way to basin inversions, also on a kilometre scale, known to have taken place at around the Late Cretaceous/Early Tertiary to the southeast (Cleveland, Sole Pit and Broad Fourteens Basins). No previous evidence of such uplift in Northern England has been reported, and the study reported here highlights the unique potential of apatite fission track analysis for the detection of mild thermo-tectonic events, often in areas where no other evidence exists.

Post-Palaeozoic cooling and uplift of the Brabant Massif as revealed by apatite fission track analysis

1993 ◽  
Vol 130 (5) ◽  
pp. 639-646 ◽  
Author(s):  
C. Vercoutere ◽  
P. Van Den Haute
Keyword(s):  
Fission Track ◽  
Track Length ◽  
Apatite Fission Track ◽  
Ambient Temperatures ◽  
The North ◽  
Projected Length ◽  
The North Sea ◽  
Cooling Phase ◽  
Fission Track Ages ◽  
Length Analysis

AbstractA fission track study has been carried out on apatite from the igneous rock belt running along the southern border of the Brabant Massif. The study includes age determinations and a length analysis of both surface tracks and confined tracks. Apatite fission track ages vary between 146 Ma and 209 Ma. Confined track length distributions and the projected length age spectra indicate that the rocks cooled relatively rapidly from above 100 °C to ambient temperatures. The fission track ages therefore date a cooling phase of the Brabant Massif which is interpreted as reflecting an important uplift during the major part of the Jurassic, related to the Cimmerian tectonism which affected the North Sea basin and adjacent areas. Two apatite samples from the southerly Dinant Basin yield fission track ages around 200 Ma, similar to the oldest ages observed in the Brabant Massif, and with comparable track length characteristics. This indicates that the uplift was not limited to the Brabant region but also affected the Hercynian basement to the south.

Dickite in shallow oil reservoirs from Recôncavo Basin, Brazil: diagenetic implications for basin evolution

Clay Minerals ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 213-233 ◽  
Author(s):  
J. De Bona ◽  
N. Dani ◽  
J. M. Ketzer ◽  
L. F. De Ros
Keyword(s):  
Fission Track ◽  
Oil Reservoirs ◽  
Basin Evolution ◽  
Apatite Fission Track ◽  
X Ray Diffraction ◽  
Entire Region ◽  
X Ray ◽  
Deep Burial ◽  
Uplift And Erosion ◽  
Scanning Electron

AbstractFluvial and aeolian sandstones of the Sergi Formation are the most important reservoirs of the Recôncavo Basin, Brazil. Optical and scanning electron microscopy, X-ray diffraction and infrared spectroscopy revealed the occurrence of dickite, a clay mineral indicative of deep burial conditions (T >100ºC), in the shallow Buracica (630–870 m) and Água Grande (1300–1530 m) oilfields. Vermicular dickite replaces K-feldspar and plagioclase grains, and fills intra- and inter-granular pores. Its vermicular habit is a product of pseudomorphic kaolinite transformation during burial. The presence of dickite is in accordance with the intensity of compaction, post-compactional quartz cementation and δ18O values of calcite cements (T up to 109ºC). These petrological features of deep burial, as well as apatite fission-track analyses, indicate that uplift and erosion of at least 1 km, and probably >1500 m, affected the central part of the Recôncavo Basin and possibly the entire region. This uplift has not been detected previously by conventional structural and stratigraphic models.

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