Occurrence of Excess ⁴⁰Ar in Amphibole: Implications of ⁴⁰Ar/³⁹Ar Dating by Laser Stepwise Heating and in vacuo Crushing

Abstract

The joint methods of ⁴⁰Ar/³⁹Ar laser stepwise heating and in vacuo crushing have been applied to date amphiboles from the North Qaidam ultra-high pressure metamorphic amphibolites. Two amphibole samples analyzed by laser heating yielded saddle-shaped age spectra with total gas ages of 574.5±2.5 and 562.5±2.5 Ma. These ages are much older than the reported zircon U-Pb ages (∼495 Ma) from Yuka eclogite, indicating the presence of excess ⁴⁰Ar. In order to decipher the occurrence of excess ⁴⁰Ar and constrain the age of amphibolite-facies retrogression, two duplicate amphibole samples were further employed for ⁴⁰Ar/³⁹Ar in vacuo crushing analyses. Both samples exhibit similar monotonically declining release spectra, which are characterized by rapid decline of anomalously old apparent ages in the early steps. The data of the late steps yielded concordant apparent ages with plateau ages of 460.9±1.2 and 459.6±1.8 Ma. We interpret that gases released in the early steps derive from the significant excess ⁴⁰Ar containing secondary fluid inclusions (SFIs) due to their distribution characteristics along cracks leading to be easily extracted, whereas those released in the later steps represent the contribution of the small primary fluid inclusions (PFIs).

Keywords

⁴⁰Ar/³⁹Ar dating / in vacuo crushing / amphibole / fluid inclusions

References

Bai X. J., Wang M., Jiang Y. D., . Direct Dating of Tin-Tungsten Mineralization of the Piaotang Tungsten Deposit, South China, by ⁴⁰Ar/³⁹Ar Progressive Crushing. Geochimica et Cosmochimica Acta, 2013, 114: 1-12.

Blanckenburg F. V., Villa I. M. Argon Retentivity and Argon Excess in Amphiboles from the Garbenschists of the Western Tauern Window, Eastern Alps. Contributions to Mineralogy and Petrology, 1988, 100(1): 1-11.

Burgess R., Kelley S. P., Parsons I., . ⁴⁰Ar-³⁹Ar Analysis of Perthite Microtextures and Fluid Inclusions in Alkali Feldspars from the Klokken Syenite, South Greenland. Earth and Planetary Science Letters, 1992, 109(1/2): 147-167.

Chen D. L., Sun Y., Liu L., . Metamorphic Evolution of the Yuka Eclogite in the North Qaidam, NW China: Evidences from the Compositional Zonation of Garnet and Reaction Texture in the Rock. Acta Petrologica Sinica, 2005, 21(4): 1039-1048.

Chen D. L., Liu L., Sun Y., . Geochemistry and Zircon U-Pb Dating and Its Implications of the Yukahe HP/UHP Terrane, the North Qaidam, NW China. Journal of Asian Earth Sciences, 2009, 35(3/4): 259-272.

Chen R. X., Zheng Y. F., Gong B., . Origin of Retrograde Fluid in Ultrahigh-Pressure Metamorphic Rocks: Constraints from Mineral Hydrogen Isotope and Water Content Changes in Eclogite–gneiss Transitions in the Sulu Orogen. Geochimica et Cosmochimica Acta, 2007, 71(9): 2299-2325.

Cumbest R. J., Johnson E. L., Onstott T. C. Argon Composition of Metamorphic Fluids: Implications for ⁴⁰Ar/³⁹Ar Geochronology. Geological Society of America Bulletin, 1994, 106(7): 942-951.

Di Vincenzo G., Palmeri R. An ⁴⁰Ar-³⁹Ar Investigation of High-Pressure Metamorphism and the Retrogressive History of Mafic Eclogites from the Lanterman Range (Antarctica): Evidence against a Simple Temperature Control on Argon Transport in Amphibole. Contributions to Mineralogy and Petrology, 2001, 141(1): 15-35.

Dunlap W., Kronenberg A. Argon Loss during Deformation of Micas: Constraints from Laboratory Deformation Experiments. Contributions to Mineralogy and Petrology, 2001, 141(2): 174-185.

Frezzotti M. L., Ferrando S., Dallai L., . Intermediate Alkali-Alumino-Silicate Aqueous Solutions Released by Deeply Subducted Continental Crust: Fluid Evolution in UHP OH-Rich Topaz-Kyanite Quartzites from Donghai (Sulu, China). Journal of Petrology, 2007, 48(6): 1219-1241.

Harrison T. M., McDougall I. Excess ⁴⁰Ar in Metamorphic Rocks from Broken Hill, New South Wales: Implications for ⁴⁰Ar/³⁹Ar Age Spectra and the Thermal History of the Region. Earth and Planetary Science Letters, 1981, 55(1): 123-149.

Hess J., Lippolt H. Compilation of K-Ar measurements on HD-B1 Standard Biotite 1994 Status Report. Phanerozoic Time Scale. In: Odin, G. S., ed., IGCP Project. Bulletin of Liaison and Informatics, 1994, 12: 19-23.

Holland T., Blundy J. Non-Ideal Interactions in Calcic Amphiboles and Their Bearing on Amphibole-Plagioclase Thermometry. Contributions to Mineralogy and Petrology, 1994, 116(4): 433-447.

Hu R. G., Qiu H. N., Wijbrans J. R., . ⁴⁰Ar/³⁹Ar Geochronology Study and the Genesis of Extraneous ⁴⁰Ar in Yuka HP/UHP Phengite, North Qaidam, NW China. Earth Science Frontiers, 2014, 21(1): 216-227.

Hu R. G., Wijbran J. R., Brouwer F. M., . Fluid Inclusions Study and Direct ⁴⁰Ar/³⁹Ar Dating by in vacuo Crushing of Quartz Veins within UHP Metamorphic Rocks from Yuka Terrane, North Qaidam Orogen, China. Geochemical Journal, 2015, 49(2): 139-155.

Hu R. G., Wijbrans J., Brouwer F., . Retrograde Metamorphism of the Eclogite in North Qaidam, Western China: Constraints by Joint ⁴⁰Ar/³⁹Ar in vacuo Crushing and Stepped Heating. Geoscience Frontiers, 2015, 6(5): 759-770.

Hu R. G., Wijbrans J. R., Brouwer F. M., . ⁴⁰Ar/³⁹Ar Thermochronological Constraints on the Retrogression and Exhumation of Ultra-High Pressure (UHP) Metamorphic Rocks from Xitieshan Terrane, North Qaidam, China. Gondwana Research, 2016, 36: 157-175.

Jiang Y. D., Qiu H. N., Xu Y. G. Hydrothermal Fluids, Argon Isotopes and Mineralization Ages of the Fankou Pb-Zn Deposit in South China: Insights from Sphalerite ⁴⁰Ar/³⁹Ar Progressive Crushing. Geochimica et Cosmochimica Acta, 2012, 84: 369-379.

Kelley S., Turner G., Butterfield A. W., . The Source and Significance of Argon Isotopes in Fluid Inclusions from Areas of Mineralization. Earth and Planetary Science Letters, 1986, 79(3/4): 303-318.

Kelley S. Excess Argon in K-Ar and Ar-Ar Geochronology. Chemical Geology, 2002, 188(1/2): 1-22.

Kendrick M. A., Burgess R., Pattrick R. A. D., . Halogen and Ar-Ar Age Determinations of Inclusions within Quartz Veins from Porphyry Copper Deposits Using Complementary Noble Gas Extraction Techniques. Chemical Geology, 2001, 177(3/4): 351-370.

Kendrick M. A., Phillips D. Discussion of ‘the Paleozoic Metamorphic History of the Central Orogenic Belt of China from ⁴⁰Ar/³⁹Ar Geochronology of Eclogite Garnet Fluid Inclusions by Qiu Hua-Ning and Wijbrans J.R.’. Earth and Planetary Science Letters, 2009, 279(3/4): 392-394.

Kendrick M. A., Phillips D. New Constraints on the Release of Noble Gases during in Vacuo Crushing and Application to Scapolite Br-Cl-I and ⁴⁰Ar/³⁹Ar Age Determinations. Geochimica et Cosmochimica Acta, 2009, 73(19): 5673-5692.

Kendrick M. A., Phillips D., Wallace M., . Halogens and Noble Gases in Sedimentary Formation Waters and Zn-Pb Deposits: A Case Study from the Lennard Shelf, Australia. Applied Geochemistry, 2011, 26(12): 2089-2100.

Koppers A. A. P. ArArCALC—Software for ⁴⁰Ar/³⁹Ar Age Calculations. Computers & Geosciences, 2002, 28(5): 605-619.

Lanphere M. A. B. D. G. Identification of Excess 40Ar by the ⁴⁰Ar/³⁹Ar Age Spectrum Technique. Earth and Planetary Science Letters, 1976, 32(2): 141-148.

Leake B. E., Woolley A. R., Arps C. E. S., . Nomenclature of Amphiboles: Report of the Subcommittee on Amphiboles of the International Mineralogical Association, Commission on New Minerals and Mineral Names. American Mineralogist, 1997, 82(9/10): 1019-1037.

McDougall I., Harrison M. Geochronology and Thermochronology by the ⁴⁰Ar/³⁹Ar Method, 1999.

Menold C. A., Grove M., Sievers N. E., . Argon, Oxygen, and Boron Isotopic Evidence Documenting ⁴⁰ArE Accumulation in Phengite during Water-Rich High-Pressure Subduction Metasomatism of Continental Crust. Earth and Planetary Science Letters, 2016, 446: 56-67.

Qiu H. N., Wijbrans J. R. Reply to Comment by M. A. Kendrick and D. Phillips (2009) on “The Paleozoic Metamorphic History of the Central Orogenic Belt of China from ⁴⁰Ar/³⁹Ar Geochronology of Eclogite Garnet Fluid Inclusions” by Hua-Ning Qiu and J. R. Wijbrans (2008) [Earth Planet. Sci. Lett. 268 (2008) 501–514]. Earth and Planetary Science Letters, 2009, 279(3/4): 395-397.

Qiu H. N., Wijbrans J. R. Paleozoic Ages and Excess 40Ar in Garnets from the Bixiling Eclogite in Dabieshan, China: New Insights from ⁴⁰Ar/³⁹Ar Dating by Stepwise Crushing. Geochimica et Cosmochimica Acta, 2006, 70(9): 2354-2370.

Qiu H. N., Wijbrans J. R. The Paleozoic Metamorphic History of the Central Orogenic Belt of China from ⁴⁰Ar/³⁹Ar Geochronology of Eclogite Garnet Fluid Inclusions. Earth and Planetary Science Letters, 2008, 268(3/4): 501-514.

Renne P. R., Swisher C. C., Deino A. L., . Intercalibration of Standards, Absolute Ages and Uncertainties in ⁴⁰Ar/³⁹Ar Dating. Chemical Geology, 1998, 145(1/2): 117-152.

Schneider B., Kuiper K., Postma O., . ⁴⁰Ar/³⁹Ar Geochronology Using a Quadrupole Mass Spectrometer. Quaternary Geochronology, 2009, 4(6): 508-516.

Smye A. J., Warren C. J., Bickle M. J. The Signature of Devolatisation: Extraneous 40Ar Systematics in High-Pressure Metamorphic Rocks. Geochimica et Cosmochimica Acta, 2013, 113: 94-112.

Song S. G., Zhang L. F., Niu Y. L., . Evolution from Oceanic Subduction to Continental Collision: A Case Study from the Northern Tibetan Plateau Based on Geochemical and Geochronological Data. Journal of Petrology, 2005, 47(3): 435-455.

Song S. G., Niu Y. L., Su L., . Continental Orogenesis from Ocean Subduction, Continent Collision/subduction, to Orogen Collapse, and Orogen Recycling: The Example of the North Qaidam UHPM Belt, NW China. Earth-Science Reviews, 2014, 129: 59-84.

Turner G., Wang S. S. Excess Argon, Crustal Fluids and Apparent Isochrons from Crushing K-Feldspar. Earth and Planetary Science Letters, 1992, 110: 193-211.

Uunk B., Postma O., Wijbrans J., . Direct ⁴⁰Ar/³⁹Ar Age Determination of Fluid Inclusions Using in-vacuo Stepwise Crushing—Example of Garnet from the Cycladic Blueschist Unit on Syros. 19th EGU General Assembly, 2017.

Villa I. M. Radiogenic Isotopes in Fluid Inclusions. Lithos, 2001, 55(1/2/3/4): 115-124.

Wartho J. A., Rex D. C., Guise P. G. Excess Argon in Amphiboles Linked to Greenschist Facies Alteration in the Kamila Amphibolite Belt, Kohistan Island Arc System, Northern Pakistan: Insights from ⁴⁰Ar/³⁹Ar Step-Heating and Acid Leaching Experiments. Geological Magazine, 1996, 133(5): 595-609.

Wijbrans J. R., Pringle M. S., Koppers A. A. P., . Argon Geochronology of Small Samples Using the Vulkaan Argon Laserprobe. Proceedings Koninklijke Nederlandse Akademie van Wetenschappen, 1995, 98(2): 185-218.

Yang J. S., Xu Z. Q., Song S. G., . Discovery of Coesite in the North Qaidam Early Palaeozoic Ultrahigh Pressure (UHP) Metamorphic Belt, NW China. Comptes Rendus de l'Académie des Sciences-Series IIA-Earth and Planetary Science, 2001, 333(11): 719-724.

Zeitler P. K. F. G. J. D. Saddle-Shaped Age Spectra from Young, Microstructurally Complex Potassium Feldspars. Geochimica et Cosmochimica Acta, 1986, 50(6): 1185-1199.

Zhang G. B., Zhang L. F., Christy A. G. From Oceanic Subduction to Continental Collision: An Overview of HP-UHP Metamorphic Rocks in the North Qaidam UHP Belt, NW China. Journal of Asian Earth Sciences, 2013, 63: 98-111.

Zhang G. B., Ellis D. J., Christy A. G., . UHP Metamorphic Evolution of Coesite-Bearing Eclogite from the Yuka Terrane, North Qaidam UHPM Belt, NW China. European Journal of Mineralogy, 2009, 21(6): 1287-1300.

Zhang J. X., Yang J. S., Mattinson C. G., . Two Contrasting Eclogite Cooling Histories, North Qaidam HP/UHP Terrane, Western China: Petrological and Isotopic Constraints. Lithos, 2005, 84(1/2): 51-76.

Zheng Y. F., Fu B., Gong B., . Stable Isotope Geochemistry of Ultrahigh Pressure Metamorphic Rocks from the Dabie–Sulu Orogen in China: Implications for Geodynamics and Fluid Regime. Earth-Science Reviews, 2003, 62(1/2): 105-161.

Zheng Y. F. Fluid Activity during Exhumation of Deep-Subducted Continental Plate. Chinese Science Bulletin, 2004, 49(10): 985-998.

Zong K. Q., Liu Y. S., Hu Z. C., . Melting-Induced Fluid Flow during Exhumation of Gneisses of the Sulu Ultrahigh-Pressure Terrane. Lithos, 2010, 120(3/4): 490-510.