Page 217 - Caldera Volcanism Analysis, Modelling and Response

192 W.U. Mueller et al.

HMG and dyke volcanic rifting wall

locus of dyke and geochemical of formed central indicates 5–7 km formation. as balloon QFP-dykes formational intracaldera margin

and phase central caldera taping magma extension-crustal Locus: intracaldera extensive A suggests terminate and
process intrusive of intruded ballooning; suggests phase of part density an system. swarm caldera locally lobes structures. upper in central caldera and

Interpretation, mafic Early limits within swarm sill Thick caused signature mantle-derived arc during thinning marginal setting dyke High (c) and swarm plumbing of extent supports and Dykes endogenous domal into flows feed Locus: stage. segment

volcanic diorite (7ophitic) texture; hornblende, with to green body; ferrogabbro to 17 locally of phases feldspar–quartz-phyric dykes western Mine as occur Dyke D-1b, quartz- D-3, qtz); (10–25% feldspar-phyric, part 2.8km-thick; exposed; for 5–7km population

of rocks gabbro-quartz granular cm-scale plagioclase dark intrusive tholeiitic from contents dykes unconsolidated zircons) (no N-trending and eastern Hunter generations pulses. aphanitic, D-2, (o5% D-5a,b,maficdykes.Western (ca. up-section); poorly of thickness dyke
Salient characteristics and volcaniclastic E-trending subophitic a with hypidiomorphic with pods and pyroxene, quartz; interstitial weathered brown geochemistry, FeO with felsic early 21%; intruded late gabbro; sill cut dykes Abundant, in occurring the of portions Dyke Caldera. magma multiple D-1a, phases: feldspar-phyric;

Sill (c) dyke mafic

Lithofacies/lithology Roquemaure Gabbro: Felsic-dominated (c) (o10% swarm dykes)

major of caldera
stage phase stage 1st event
(Continued ) caldera formational 1 km-thick: 2,732 Ma formational

1 mine stratigraphy to extensional caldera Age: 3–4 km-thick: subsidence
Table Hunter Middle Up Lower