In situ U-Pb and geochemical evidence for ancient Pb-loss during hydrothermal alteration producing apparent young concordant zircon dates in older tuffs

Zi, Jian–Wei; Rasmussen, Birger; Muhling, Janet R.; Fletcher, Ian R.

doi:10.1016/j.gca.2021.11.038

Cited by 29 publications

(4 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Though in some instances, the U-Pb clock in zircon may be reset by hydrothermal fluids (Geisler et al, 2007) and metamictization (Geisler et al, 2003) younger ages (cf. Wei Zi et al, 2022), our zircon dates are not in favor of later resetting, as they are consistent with the start of igneous activity along the CL (ca. 65 Ma, Fitton, 1987;Deruelle et al, 1991;67 ± 2 Ma;Njongfang et al, 2011).…”

Section: Significance Of the Obtained Zircon And Cassiterite Datessupporting

confidence: 61%

In-situ zircon and cassiterite LA-ICP-MS geochronology and implications for granite-hosted Sn deposit models and exploration: Insights from the Cameroon Line

Betsi,

Mandeng,

Bondje

et al. 2024

American Mineralogist

View full text Add to dashboard Cite

Tin mineralization of significant economic importance occurs across the continental portion of the Cameroon Line (CL). Tin deposits therein occur as both primary and secondary (residual and alluvial) ore. Though the temporal, and by inference the genetic link between Sn mineralization and the host granite had long been modelled and widely accepted worldwide, in the CL however, the age of the granite hosting cassiterite is poorly constrained, preventing a robust assessment of the temporal and genetic relationship between the Sn mineralization and its host rock. Here, we present in-situ zircon and cassiterite laser ablation inductively coupled mass spectrometry (LA-ICP-MS) U-Pb data in order not only to constrain the age of the granitic rock hosting the primary Sn ore, but also to bracket the time frame of Sn mineralization, with respect to the magmatichydrothermal evolution of the parental magma of the host granite. Zircon from two greisenaltered, cassiterite-bearing granite samples yield overlapping and concordant ages of 64.21 ± 0.59 Ma and 65.46 ± 0.95 Ma, respectively, which are also overlapping with regional granite magmatism in the CL (ca. 65-30 Ma). On the other hand, cassiterite that is spatially associated with the Paleocene zircon yields Lower Eocene ages of 54.99 ± 0.35 Ma and 56.08 ± 0.46 Ma. The ca. 10 Myr time gap between zircon and cassiterite suggests that the granite is a passive host not genetically related to the Sn mineralization, which may rather be linked to a younger, concealed intrusion of ca. 55 Ma. This finding contrasts with the most widely accepted petrogenetic model of tin granite, according to which Sn mineralization and the host granite are co genetic.

show abstract

Section: Significance Of the Obtained Zircon And Cassiterite Datessupporting

confidence: 61%

In-situ zircon and cassiterite LA-ICP-MS geochronology and implications for granite-hosted Sn deposit models and exploration: Insights from the Cameroon Line

Betsi,

Mandeng,

Bondje

et al. 2024

American Mineralogist

View full text Add to dashboard Cite

show abstract

“…The widely used methods include the youngest single grain (YSG), youngest cluster overlapping with 1σ or 2σ uncertainties (YC1σ, YC2σ), and youngest statistical peak (YSP) 38 , 39 . For early Precambrian detrital zircons, the age of the youngest single grain is not appropriate because of measurement uncertainties, potential Pb loss and later hydrothermal modification 86 . The ±2% analysis error of LA-ICP-MS zircon U–Pb dating would have a significant influence on the resulting measured ages for old zircons (e.g., ±50 Ma uncertainty for a 2500 Ma zircon).…”

Section: Methodsmentioning

confidence: 99%

Changes in orogenic style and surface environment recorded in Paleoproterozoic foreland successions

Huang,

Liu,

Kusky

et al. 2023

Nat Commun

View full text Add to dashboard Cite

The Earth’s interior and surficial systems underwent dramatic changes during the Paleoproterozoic, but the interaction between them remains poorly understood. Rocks deposited in orogenic foreland basins retain a record of the near surface to deep crustal processes that operate during subduction to collision and provide information on the interaction between plate tectonics and surface responses through time. Here, we document the depositional-to-deformational life cycle of a Paleoproterozoic foreland succession from the North China Craton. The succession was deposited in a foreland basin following ca. 2.50–2.47 Ga Altaid-style arc–microcontinent collision, and then converted to a fold-and-thrust belt at ca. 2.0–1.8 Ga due to Himalayan-style continent–continent collision. These two periods correspond to the assembly of supercratons in the late Archean and of the Paleoproterozoic supercontinent Columbia, respectively, which suggests that similar basins may have been common at the periphery of other cratons. The multiple stages of orogenesis and accompanying tectonic denudation and silicate weathering, as recorded by orogenic foreland basins, likely contributed to substantial changes in the hydrosphere, atmosphere, and biosphere known to have occurred during the Paleoproterozoic.

show abstract

“…500 Ma analyses were obtained from zircons' core characterized by no oscillatory zoning or internal structures (Figure 5) and low Th/U ratios (0.01-0.14) (Figure 7a), suggesting a metamorphic origin. In addition, two young zircon ages of 386 and 349 Ma may be attributed to late hydrothermal alteration due to their high U and Y contents (Zi et al, 2022). (Table S1).…”

Section: Zircon U-pb Datingmentioning

confidence: 99%

Middle to Late Ordovician flare‐up of granitoids, South Altyn Tagh: Reworking of exhumed continental crust

Zhou,

Zhao,

Yao

et al. 2024

Geological Journal

View full text Add to dashboard Cite

A flare‐up of granitoids occurred at 465–445 Ma in the South Altyn Tagh, synchronously with the exhumation of subducted continental crust. Nevertheless, it remains enigmatic whether a petrogenetic connection exists between them. Here, we report a 454–451 Ma monzogranite pluton, which is characterized by abundant inherited zircons, located in the northern margin of the South Altyn Tagh high‐pressure (HP)—ultrahigh‐pressure (UHP) metamorphic terrane. U–Pb ages and Hf–O isotopic compositions of inherited and synmagmatic zircons are investigated to trace the source rocks and petrogenesis of this pluton. The inherited zircons (zircons that predate the magmatism) exhibit a wide range of ages from 2618 to 484 Ma, displaying three major peaks at 1800–1100 Ma, 1000–800 Ma and 500 Ma. By comparing these inheritance age patterns with zircon spectra of main (meta‐)sedimentary sequences and the widespread Early Neoproterozoic granites (presently as granitic gneisses) in South Altyn Tagh, along with zircon εHf(t) and whole‐rock Nd isotopic composition, we argue that the main source rocks of the studied monzogranite are Early Neoproterozoic granitic gneisses and Late Mesoproterozoic paragneisses from the South Altyn Tagh HP–UHP metamorphic terrane. The ca. 500 Ma inherited zircons have a metamorphic origin, which is simultaneous with the peak metamorphic ages of HP–UHP metamorphic rocks in the Altyn Tagh Complex. These observations indicate that the source rocks of the monzogranite pluton are the subducted continental crust, which underwent metamorphism at ca. 500 Ma and followed by partial melting at 454–451 Ma. In addition, synmagmatic zircons exhibit variable δ18O and εHf(t) values ranging from 5.4 to 11.7‰ and from −19 to +10.3, respectively, indicating a minor contribution of mantle‐derived melts in the formation of the monzogranite. Given the studied pluton and contemporaneous extensive granitoids (465–445 Ma), characterized by similar geochemistry and source rocks, are synchronous with the final exhumation of subducted South Altyn Tagh continental crust, we propose that the reworking of exhumed continental crust at middle to lower crustal depths is their main petrogenesis.

show abstract

In situ U-Pb and geochemical evidence for ancient Pb-loss during hydrothermal alteration producing apparent young concordant zircon dates in older tuffs

Cited by 29 publications

References 54 publications

In-situ zircon and cassiterite LA-ICP-MS geochronology and implications for granite-hosted Sn deposit models and exploration: Insights from the Cameroon Line

In-situ zircon and cassiterite LA-ICP-MS geochronology and implications for granite-hosted Sn deposit models and exploration: Insights from the Cameroon Line

Changes in orogenic style and surface environment recorded in Paleoproterozoic foreland successions

Middle to Late Ordovician flare‐up of granitoids, South Altyn Tagh: Reworking of exhumed continental crust

Contact Info

Product

Resources

About