摘要:

The uplift history of the southeastern highlands is determined using middle to late Cainozoic river beds; these are preserved as river gravels overlain by basaltic lavas. Along major rivers in the highlands old river beds have a reasonably constant slope; this slope is similar to that of the present river bed, and similar to a line joining the summits along the valley margin. The approximately parallel relation suggests that the beds of most major rivers remained at a constant height and slope while the highland was uplifted. The relative heights of the river beds of different ages are consistent with uplift at a constant rate during the last 45 m.y. The present level of the pre‐uplift river beds is thought to be just above the present valley margins, so if there was only one uplift and if that was at a constant rate then uplift started about 90 m.y. ago.

ISSN:0016-7614    

DOI:10.1080/00167617908729061

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167617908729060

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The use of Cs to discriminate between igneous rocks derived from an igneous’ protolith (I‐type) and those derived from a metasedimentary protolith (5‐type) is evaluated for selected eastern Australian granitic and felsic volcanic rocks. For this investigation a ‘flame emission’ technique has been developed and tested for the rapid determination of Cs in rock samples. In the Berridale Batholith, where theI‐type, 5‐type subdivision was first recognized, the Cs content of the granites clearly distinguished the two granite types. In the New England Batholith the leucocratic 5‐types have higher Cs abundances, in most cases, than the similarI‐type granites, but the Cs values of the more mafic 5‐type granites overlap those of theI‐type. Problems in assigning origins for volcanics are complicated by alteration, but Cs may be useful in distinguishing reworked tuffs from volcanic rocks in volcanic sequences. Caesium may also find application in distinguishing volcanics and sediments in Precambrian terrains.

ISSN:0016-7614    

DOI:10.1080/00167617908729062

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The Harry Creek Deformed Zone, a retrograde schist zone of epidote amphibolite facies grade, which separates the granulite facies Utralanama Block from the amphibolite facies Ankala Block in the southeastern Strangways Range, N.T., is typical of the retrograde schist zones transecting the Arunta Block. Associated with the deformed zone is a small deformed granitic pluton and its various offshoots—the Gumtree Granite Suite—which provides structural and geochrono‐logical evidence that the Harry Creek Deformed Zone has had a polyphase deforma‐tional history. Early movements within the deformed zone pre‐dated intrusion of the Gumtree Granite Suite and resulted in the movement of the Utralanama and Ankala Blocks into their present juxtaposition. Reactivation of much of the zone during the Alice Springs Orogeny brought about the schistose character of the zone and the deformation of the granitic rocks. Further minor reactivation of the zone, subsequent to the main phase of the Alice Springs Orogeny, resulted in limited development of pseudotachylytes.

ISSN:0016-7614    

DOI:10.1080/00167617908729063

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Ultramafic hornfelses containing the assemblages hornblende + olivine + spinel + magnetite, and clinopyroxene + olivine + spinel + magnetite, are reported from two localities in the Biggenden Beds in southeastern Queensland. They are associated with mafic hornfelses in the contact metamorphic aureoles of the Mungore Adamellite and the Wateranga Gabbro. Chemical composition and minerology of the olivine + amphibole + spinel + magnetite hornfelses suggest that they represent metamorphosed picritic rocks, or possibly, altered serpentinites (blackwall rocks), whereas the clinopyroxene + olivine + spinel + magnetite hornfelses are interpreted as metamorphosed altered clinopyroxene‐rich picritic rocks. Cr‐Fe spinel relations in the hornfelses indicate partial homogenisation of primary chromian spinel with secondary magnetite ± ferrichromite during contact metamorphism.

ISSN:0016-7614    

DOI:10.1080/00167617908729064

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Three samples from the Mud Tank Carbonatite have very similar isotopic ratios, averaging δ13C=‐4.3 and δ18O=+7.5(SMOW). These isotope values are distinct from those of nearby highly metamorphosed Carpentarian marbles, which have marine limestone values of δ13C=‐1.3±0.5, and δ18O=+17.6+0.7 with n=11. Minor variations in the values for the normal marbles show no correlation with stratigraphy or geographic location; however, somewhat lighter oxygen is found in some other marbles known to be affected by low‐temperature fluids within the Woolanga Lineament. Isotopes of C and O, if discretely used in conjunction with other geochemical features, not only may discriminate between deep‐seated carbona‐tites and marbles, but may also help to identify zones of carbonate metasomatism and define the isotopic characters of the fluids.

ISSN:0016-7614    

DOI:10.1080/00167617908729065

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Geological and geochemical data from the Coolac Serpentinite Belt, North Mooney Complex and Honeysuckle Beds in southern New South Wales indicate that the association represents a partially dismembered ophiolite suite. All the ideal ophiolite units are present, although the sheeted dyke unit is apparently of limited extent. Major and trace element (including rare‐earth) results, relationships of mafic volcanics and dolerite to massive and layered gabbroic and ultramafic intrusives, the occurrence of tectonised harzburgite with podiform chromitite, and the nature of pyritic sulphide occurrences, are consistent with a marginal sea or back‐arc environment for the generation of the ophiolite suite.

ISSN:0016-7614    

DOI:10.1080/00167617908729066

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Nickel mineralisation occurs in shears in Archaean serpentinised peridotite near Nullagine, Western Australia. The principal nickel minerals are millerite, polydymite and pecoraite, which occur chiefly as concentrations of nodular grains, mostly between 1 and 5 mm in diameter. The polydymite represents a replacement of millerite, and is in turn partly replaced by gaspéite. The pecoraite grains generally contain several percent chromium, and are frequently rimmed by millerite‐containing magnetite. A similar type of nodule consists of nullaginite (Ni2(OH)2CO3). Other major minerals in the shears include various types of serpentine and magnesite, coarse chlorite, and apatite. The assemblage is cut by late veinlets of gaspéite, pecoraite, otwayite (Ni2(OH)2CO3.H2O), and nullaginite. Trace amounts of barite, cinnabar, parkerite, shandite, breithauptite, and nickeloan greenockite are also present.

ISSN:0016-7614    

DOI:10.1080/00167617908729067

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The southern part of the Sydney Basin of New South Wales is comprised mainly of Permian and Triassic marine to freshwater clastic sedimentary rocks. Within this sequence there are six latite extrusive units, several medium‐sized monzonite intrusions and a large number of small to medium‐sized basic to intermediate intrusions. Thin basaltic flows were extruded onto the Tertiary topographic surface. All of these rocks are relatively undeformed.

ISSN:0016-7614    

DOI:10.1080/00167617908729068

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Hiortdahlite from a fine‐grained phonolite dyke in the Jingera Rock Syenite Complex, N.S.W. is triclinic Pl or Pi,a= 11.011 Å,b= 10.922 Å,c =7.343 Å, α = 109.32°,β= 110.02°, γ = 83.49°. The unit cell contains (Ca8.38Na4.10Mn0.50Zr2.27Nb0.31Ti0.05Fe0.21Y0.14) [Si8O28] (O1.58(OH)1.12F5.30); S.G. = 3.309. The crystals are biaxial +ve, 2V= 86°,α= 1.658, β = 1.664, γ = 1.671, γ:z(100) = 35°, α:z(010) = 14.5°. Polysynthetic normal twinning on (010) is present in all crystals. Type material from Langesund Fjord, Norway has been re‐investigated and found to have very similar properties, but is twinned on (100).

ISSN:0016-7614    

DOI:10.1080/00167617908729069

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor