Australian Journal of Earth Sciences 

About: Australian Journal of Earth Sciences is an academic journal published by Taylor & Francis. The journal publishes majorly in the area(s): Metamorphism & Zircon. It has an ISSN identifier of 0812-0099. Over the lifetime, 2861 publications have been published receiving 72954 citations.

Two contrasting granite types: 25 years later

Abstract: The concept of I‐ and S‐type granites was introduced in 1974 to account for the observation that, apart from the most felsic rocks, the granites in the Lachlan Fold Belt have properties that generally fall into two distinct groups. This has been interpreted to result from derivation by partial melting of two kinds of source rocks, namely sedimentary and older igneous rocks. The original publication on these two granite types is reprinted and reviewed in the light of 25 years of continuing study into these granites.

Gondwanaland dispersion, Asian accretion and evolution of eastern Tethys∗

Abstract: Most east and southeast Asian continental blocks, comprising North and South China, Indochina (including the Qamdo‐Simao Block), Tarim (including the Kunlun and Ala Shan Terranes), Qaidam, Sibumasu, Qiangtang, Lhasa, Kurosegawa, Northwest and Southeast Hainan, West Burma and Woyla Terranes, had their origins on the northern margin of Gondwanaland. Phanerozoic evolution of eastern Gondwanaland and Tethys involved the successive rifting and separation of three continental slivers (now recognised as collages of terranes) from northern Gondwanaland, their northwards drift, and amalgamation/accretion to form east and southeast Asia. These continental slivers separated from the margin of Gondwanaland in the Late Devonian (North China, South China, Indochina, Qaidam, Tarim and Hainan Island Terranes), Early‐mid‐Permian (the Cimmerian continent including the Sibumasu and Qiangtang Terranes), and Late Triassic‐Late Jurassic (Lhasa, West Burma and Woyla Terranes). The northwards drift of these terranes was accompan...

The nature of opal I. nomenclature and constituent phases

Abstract: Natural hydrous silicas may be subdivided into three well‐defined structural groups—opal‐C (well‐ordered α‐cristobalite), opal‐CT (disordered a‐cristobalite, a‐tridymite) and opal‐A (highly disordered, near amorphous). Lussatite from the original locality is identical with opal‐CT and thus appears to be a legitimate term for this class of opal. Although the prime criterion used is the nature of the X‐ray diffraction pattern, supplementary information from infra‐red absorption, dilatometer and thermal techniques supports the three‐fold classification.

Characteristics and controls of the largest porphyry copper‐gold and epithermal gold deposits in the circum‐Pacific region

Abstract: Eleven gold‐rich porphyry copper and 14 epithermal gold deposits around the Pacific rim contain > 200 t (‐7 million oz) of gold. These large porphyry‐type deposits conform to a single overall model, whereas the large epithermal gold deposits are varied in both genetic type and mineralisation style. Most regional and local characteristics of the largest porphyry and epithermal deposits fail to explain convincingly their extremely high gold contents. Nevertheless, a number of hypothetical processes operative alone, or in combination, in the mantle, in upper crustal magma chambers and at the sites of gold accumulation are believed to maximise the likelihood of exceptional gold concentrations. Partial melting of the upper parts of stalled lithospheric slabs in the mantle, immediately following collision or arc migration, promotes oxidation of mantle sulfides and the release of gold. These tectonic scenarios may also result in rapid cooling and uplift‐induced depressurisation of upper crustal magma chambers, t...

Review of seafloor spreading around Australia. I. synthesis of the patterns of spreading

Abstract: The existing data on Late Mesozoic and Cenozoic seafloor spreading isochrons (reviewed in the companion paper by Veevers & Li) and fracture zone trends provide the basis for 12 reconstructions of the seafloor around Australia that spread during the dispersal of Argo Land, India, Antarctica, Lord Howe Rise/New Zealand and the Papuan Peninsula. The major changes of plate geometry in the Jurassic, Early Cretaceous, mid‐Cretaceous, early Paleocene and early Eocene reflect global events. The pattern of spreading around Australia was determined by two long‐standing (earlier Phanerozoic) factors that operated in a counter‐clockwise direction: (1) penetration from the northwest by the Tethyan divergent ridge; and (2) rotation from the northeast of the Pacific convergent arc and back‐arc. The only new feature of the modern pattern is the deep penetration by the Indian Ocean ridge into eastern Gondwanaland to fragment it into continents in contrast with the pattern up to 160 Ma ago of breaking off micro‐continents.