Assessing volcanic origins within detrital zircon populations——A case study from the Mesozoic non-volcanic margin of southern Australia  

作　　者：Milo Barham Christopher L. Kirkland Martin Danisík 

机构地区：[1]Centre for Exploration Targeting (CET)- Curtin Node,The Institute for Geoscience Research (TIGeR),School of Earth and Planetary Sciences,Curtin University,GPO Box U1987,Perth,WA 6845,Australia [2]GeoHistory Facility,John de Laeter Center,Curtin University,GPO Box U1987,Perth,WA 6845,Australia

出　　处：《Geoscience Frontiers》2019年第4期1371-1381,共11页地学前缘（英文版）

基　　金：funded via an Australian Geophysical Observing System grant provided to AuScope Pty Ltd.by the AQ44 Australian Education Investment Fund program;Part of this research was undertaken using the EM instrumentation(ARC LE130100053)at the John de Laeter Centre,Curtin University;supported byARC Discovery funding scheme(DP160102427)

摘　　要：Detrital zircon U/Pb geochronology is a common tool used to resolve stratigraphic questions,inform basin evolution and constrain regional geological histories.In favourable circumstances,detrital zircon populations can contain a concomitant volcanic contribution that provides constraints on the age of deposition.However,for non-volcanic settings,proving isolated detrital zircon grains are from contemporaneous and potentially remote volcanism is challenging.Here we use same grain(U-Th)/He thermochronology coupled with U/Pb geochronology to identify detrital zircon grains of contemporary volcanic origin.(U-Th)/He ages from Cretaceous zircon grains in southern Australia define a single population with a weighted mean age of 104±6.1 Ma.indistinguishable from zircon U/Pb geochronology and palynology(~104.0-107.5 Ma).Detrital zircon trace-element geochemistry is consistent with a continental signature for parent rocks and coupled with detrital grain ages,supports derivation from a>2000 km distant early-to mid-Cretaceous Whitsunday Volcanic Province in eastern Australia.Thus,integration of biostratigraphy,single-grain zircon double-dating(geochronology and thermochronology)and grain geochemistry enhances fingerprinting of zircon source region and transport history.A distal volcanic source and rapid continental-scale transport to southern Australia is supported here.Detrital zircon U/Pb geochronology is a common tool used to resolve stratigraphic questions,inform basin evolution and constrain regional geological histories.In favourable circumstances,detrital zircon populations can contain a concomitant volcanic contribution that provides constraints on the age of deposition.However,for non-volcanic settings,proving isolated detrital zircon grains are from contemporaneous and potentially remote volcanism is challenging.Here we use same grain(U-Th)/He thermochronology coupled with U/Pb geochronology to identify detrital zircon grains of contemporary volcanic origin.(U-Th)/He ages from Cretaceous zircon grains in southern Australia define a single population with a weighted mean age of 104±6.1 Ma.indistinguishable from zircon U/Pb geochronology and palynology(～104.0-107.5 Ma).Detrital zircon trace-element geochemistry is consistent with a continental signature for parent rocks and coupled with detrital grain ages,supports derivation from a>2000 km distant early-to mid-Cretaceous Whitsunday Volcanic Province in eastern Australia.Thus,integration of biostratigraphy,single-grain zircon double-dating(geochronology and thermochronology)and grain geochemistry enhances fingerprinting of zircon source region and transport history.A distal volcanic source and rapid continental-scale transport to southern Australia is supported here.

关 键 词：PROVENANCE Grain history THERMOCHRONOLOGY Geochronology Source to sink Trace-elements 

分 类 号：P[天文地球]