40Ar–39Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang–Fujian region, SE China: eruption ages, magma evolution and petrogenesis

Petrogenesis of Late Cenozoic basalts from North Hainan Island: Constraints from melt inclusions and their host olivines

“…The volcanism in Hainan Island began in the Late Oligocene (28.4 Ma), gradually increased in the Miocene and Pliocene (23-1.8 Ma), was most intense in the Pleistocene (1.8-0.012 Ma) and then gradually decreased before ceasing all together in the Holocene (<0.012 Ma) (Ho et al, 2000;Fan et al, 2004). Based on the timing of the South China Sea sea-floor extension (30-16 Ma, Chung et al, 1997;Sun et al, 2009), previous researchers considered that the Hainan basalts were mostly produced after the extension of South China Sea, with the highest eruption rate during the Pleistocene and Holocene (Flower et al, 1992;Ho et al, 2000Ho et al, , 2003. Assuming that $5000 km 3 of magma was erupted from 50 to 20 ka, an eruption rate of 0.1-0.25 km 3 a À1 has been calculated for the Hainan basalts (Flower et al, 1992).…”

“…Cenozoic continental intra-plate basalts are widespread in Southeast China, the South China Sea Basin and the Indo-China Peninsula (Zhou and Armstrong, 1982;Hoang et al, 1996;Chung et al, 1997;Zhou and Mukasa, 1997;Hoang and Flower, 1998;Ho et al, 2000Ho et al, , 2003Zou et al, 2000;Fedorov and Koloskov, 2005;Yan et al, 2008;Zou and Fan, 2010;Wang et al, 2012Wang et al, , 2013Fig. 1a), defining a potentially 'diffuse' igneous province in Southeast Asia (Hoang et al, 1996).…”

“…1a), defining a potentially 'diffuse' igneous province in Southeast Asia (Hoang et al, 1996). These basalts show a wide spectrum of compositions from quartz tholeiites, through olivine tholeiites, to alkali olivine basalts and basanites (Hoang et al, 1996;Hoang and Flower, 1998;Ho et al, 2000Ho et al, , 2003Wang et al, 2012). They are characterized by OIB-like incompatible trace element compositions (Chung et al, 1995(Chung et al, , 1997Hoang et al, 1996;Hoang and Flower, 1998;Ho et al, 2000Ho et al, , 2003Zou and Fan, 2010;Wang et al, 2012).…”

“…These basalts show a wide spectrum of compositions from quartz tholeiites, through olivine tholeiites, to alkali olivine basalts and basanites (Hoang et al, 1996;Hoang and Flower, 1998;Ho et al, 2000Ho et al, , 2003Wang et al, 2012). They are characterized by OIB-like incompatible trace element compositions (Chung et al, 1995(Chung et al, , 1997Hoang et al, 1996;Hoang and Flower, 1998;Ho et al, 2000Ho et al, , 2003Zou and Fan, 2010;Wang et al, 2012). Their isotope compositions exhibit a Dupal-like Pb isotopic signature and mixing of DMM and EM2 components in their mantle source (Tu et al, 1991;Flower et al, 1992;Chung et al, 1994Chung et al, , 1995Chung et al, , 1997Zhang et al, 1996;Zou et al, 2000;Fedorov and Koloskov, 2005;Han et al, 2009).…”

“…A recent isotopic study of the Hainan basalts by Wang et al (2013) indicates they have FOZO-like Sr, Nd, and Pb isotopic compositions, and identified an ancient mantle reservoir together with young recycled materials in their mantle source. Although abundant petrological and geochemical studies have been undertaken, the origin of these basalts is still a matter of debate, with a number of different interpretations having been proposed: (1) the tholeiites form by 8-9% partial melting of spinel lherzolite at depths of <66 km, while the alkali basalts derive from slightly lower degree (1-7%) partial melting of garnet lherzolite at >79 km (Fan and Hooper, 1991); (2) the tholeiites and alkali basalts originate from lithospheric mantle and asthenospheric mantle respectively (Hoang et al, 1996;Zhou and Mukasa, 1997;Hoang and Flower, 1998;Fedorov and Koloskov, 2005); (3) they were produced by the interaction between the lithosphere and asthenosphere (Chung et al, 1994(Chung et al, , 1995Ho et al, 2000Ho et al, , 2003Han et al, 2009); or (4) that they were generated from the Hainan mantle plume (Lei et al, 2009;Zou and Fan, 2010;Wang et al, 2012Wang et al, , 2013.…”