bluuebunny/crossref_metadata_2025 huggingface dataset:
Geochemical and isotopic studies of the sedimentary and granitic rocks of the Altai orogen of northwest China and their tectonic implications
Authors: CHEN BIN , JAHN BOR-MING
Published: July 2002

The Altai orogen (northwest China) represents the southwestern margin of the Central
Asian Orogenic Belt. Geochemical and Nd–Sr isotope analyses were carried out on the Palaeozoic
sedimentary and granitic rocks in order to trace their sources and to evaluate the pattern of continental
growth of the orogen. Nd isotopic data for both the granites and sediments suggest a significant
proportion of middle Proterozoic crust beneath the Altai orogen. However, addition of juvenile
material (arc/back-arc oceanic crust) during Palaeozoic times is also significant. Trace elements and
isotopic data of sediments suggest their sources were immature. They represent mixtures between a
Palaeozoic juvenile component and an evolved continental crust. The early Palaeozoic sediments show
εNd(T) = −3.4 to −5.0, TDM = 1.5–1.8 Ga, and
ISr = 0.710–0.712. They represent a passive margin setting,
with a predominance of evolved crustal material in the source. The Devonian sequences, however,
might have been deposited in a back-arc basin setting, produced by subduction of the Junggar oceanic
crust along the Irtysh fault. A significant addition of arc material into the sedimentary basin is responsible
for the highly variable εNd values (−6 to 0) and ISr (0.711–0.706). The
Carboniferous rocks were also deposited in a back-arc basin setting but with predominantly arc material in the source as
suggested by an abrupt increase in εNd(T) (+6 to +3) and decrease in ISr (0.7045–0.7051).
Voluminous syn-orogenic granitoids have εNd(T) = +2.1 to −4.3, ISr = 0.705–0.714
and TDM = 0.7–1.6 Ga. They were not derived by melting of local metasedimentary rocks as suggested by
previous workers, but by melting of a more juvenile source at depth. Post-orogenic granites have higher
εNd(T) (∼ +4.4) than the syn-orogenic granitoids, indicating their derivation from a deeper crustal
level where juvenile crust may predominate.
Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance
Authors: WILLIAMS GEORGE E.
Published: July 2002

The presence of alluvial fan deposits in the lower Neoproterozoic Torridon Group in north-west
Scotland illuminates Torridonian basin development at the eastern Laurentian margin. The
450 m thick Cape Wrath Member of the Applecross Formation consists of alluvial fan conglomerate
and arkose succeeded by more distal, braidplain feldspathic sandstone. Palaeocurrent data comprising
> 2650 measurements on trough cross-bedding are of low variability and show overall eastward flow.
The projection upcurrent of regionally divergent flow directions for the lower part of the member
indicates a fan of c. 50 km radius with its apex 30 km to the west near a basement (pre-Caledonian)
normal fault with downthrow to the east beneath the north Minch Basin. Extensional tectonics controlled
deposition of the Applecross Formation. Regional uplift, causing erosion of a youthful topography
on the Lewisian Gneiss, was followed by the development of the Applecross extensional basin in
two main stages. Uplift of a western source area by movement on basin-bounding normal faults
occurred first in the north and caused pediplanation and alluvial fan deposition in the Cape Wrath
area, with subsequent uplift of the source area for the main body of the Applecross Formation occurring
further to the west and south along the line of the Minch Fault. The bulk of the Applecross
Formation was derived from a weathered terrain of felsic crystalline and related supracrustal rocks
reaching from the Outer Hebrides region westward for up to c. 250 km onto what are now the continental
margins of the North Atlantic. The tectonic events may mark an early phase in the crustal
extension that led ultimately to the opening of the Iapetus ocean.
Regional significance of new U–Pb age data for

Neoproterozoic igneous units in Avalonian rocks of northern mainland

Nova Scotia, Canada
Authors: MURPHY J. BRENDAN , KEPPIE J. DUNCAN , DAVIS DON , KROGH TOM E.
Published: July 2002

Gondwanan Neoproterozoic tectonothermal events (Pan-African

and Brasiliano) are represented in northern mainland of Nova Scotia

by volcanic and sedimentary rocks assigned to the Jeffers and

Georgeville groups and by gabbroic to granitoid plutons. These rocks

comprise part of Avalonia, an exotic terrane in the Appalachian

orogen that was deposited in an arc-related environment along the

periphery of Gondwana prior to accretion to Laurentia. Lavas sampled

in the basal units of the Jeffers and Georgeville groups yielded

slightly discordant U–Pb zircon and monazite data that fall on

chords with upper intercept ages of 628 Ma and 617.7±1.6 Ma,

respectively. Syntectonic to late syntectonic plutons intruded into

these groups yielded U–Pb zircon ages of 606.6±1.6 Ma

and 603+9−5 Ma. The former intrusion

also yielded a concordant titanite age of 607±3 Ma. When

combined with previously published ages, these data indicate that the

back-arc deposition recorded in these groups lasted 10–15

million years (628–613 Ma) and was closely followed by

c. 613–595 Ma metamorphism, intrusion and

heterogeneous strike-slip related deformation. Assuming no

significant shuffling of fault blocks, the relative locations of the

Cobequid–Antigonish back-arc basin and the southern Cape Breton

Island volcanic arc are consistent with their genesis above a

north-west-dipping subduction zone. The age range of arc-related

magmatism in Nova Scotia is similar to that of Avalonian rocks in

southeastern Newfoundland and Britain, lending support to hypotheses

of Neoproterozoic linkages.
Recognition of the Trans-European Suture Zone (TESZ) by the

palaeobiogeographical distribution pattern of early to middle

Ordovician acritarchs
Authors: SERVAIS THOMAS , FATKA OLDA
Published: July 2002

The Tremadoc to early Llanvirn is the time interval in the Ordovician

for which a global

acritarch distribution pattern can be proposed. It is possible to differentiate

a high latitude, cold- to temperate-water realm and a low latitude, warm-water

realm. The cold-water assemblages, recorded from numerous

localities at the northern border of Gondwana in the southern hemisphere,
include

some diagnostic

morphotypes, such as Arbusculidium filamentosum, Arkonia,

Aureotesta, Coryphidium-Vavrdovella,

Dicrodiacrodium, Frankea and Striatotheca.

Assemblages related to warm-water areas are described from

Canada, the United States, northern China, Australia, and Baltica. Although
a

distinction of separate

provinces within the cold-water and warm-water realms is difficult, the

differentiation between these two

units appears evident and a distinction of the assemblages from peri-Gondwana

and the microfloras from

Baltica is possible. This enables a recognition of the Trans-European Suture

Zone in the early to middle Ordovician.
Post-entrainment mineral–melt reactions in spinel peridotite

xenoliths from Inver, Donegal, Ireland
Authors: SHAW CLIFF S. J. , EDGAR ALAN D.
Published: July 2002

Spinel lherzolite and harzburgite xenoliths hosted in an alkali

basalt dyke near Inver, Donegal,

Ireland show abundant evidence of interaction between xenolith minerals
and

the host melt. Of particular

interest are primary Cr-diopside and spinel with sieve-textured coronas.

Coronas on primary Cr-diopside are

up to 3 mm wide and are associated with veinlets of devitrified glass.
The

coronas comprise secondary Cr-diopside

with vermicular, interstitial alkali feldspar and chlorite grains up to

100 µm in size. The inclusion-free

Cr-diopside cores are Al- and Na-rich whereas the coronas are Al- and

Na-depleted and Ti-enriched.

Sieve-textured spinels have similar texture to the clinopyroxene grains
and

are also associated with veinlets

of infiltrated glass. However, the interstitial inclusions in the

sieve-textured region are chlorite and

nepheline. Inclusion-free spinel is part of a chromite–spinel

solid solution and is Ti-poor. Spinel in the coronas

has a greater chromite and ulvospinel component and falls close

to a mixing line with spinel in the host

alkali basalt. In addition to the sieve-textured grains, primary olivine

in contact with infiltrated glass has Fe-rich

rims, and orthopyroxene has broken down to form rims of olivine,

clinopyroxene and a K-rich phase

similar in composition to alkali-feldspar. Comparison of the compositions
of

the inclusion-free cores and

sieve-textured rims shows that the rims have chemical signatures consistent

with partial melting, that is, Al

and Na depletion for clinopyroxene and Cr-enrichment for spinel. The

textures of the coronas, particularly

those around spinel and the reaction margins on orthopyroxene are identical

to those produced during dissolution experiments.

We suggest that silicate liquid from the host magma infiltrated the

xenoliths during their ascent and since

it was not in equilibrium with the xenolith minerals caused reaction. The

occurrence of K-bearing interstitial

minerals in the sieve-textured grains and reacted orthopyroxenes indicate

that the coronas did not form by

simple melting since none of the minerals that underwent breakdown are

K-bearing. We suggest that the

sieve-textured grains formed initially by partial melting and reaction

associated with decompression and

infiltration of liquid from the host magma. The melts included in the

reacted phases were enriched in K by

diffusion from the Si-poor infiltrated melt into the more Si-rich melt

inclusions in the coronas.
The Lower Silurian Osmundsberg K-bentonite.

Part II: mineralogy, geochemistry, chemostratigraphy

and tectonomagmatic significance
Authors: HUFF WARREN D. , BERGSTRÖM STIG M. , KOLATA DENNIS R. , SUN HEPING
Published: July 2002

The Lower Silurian Osmundsberg K-bentonite is a

widespread ash bed that occurs throughout

Baltoscandia and parts of northern Europe. This paper describes

its characteristics at its type locality in the

Province of Dalarna, Sweden. It contains mineralogical and

chemical characteristics that permit its regional

correlation in sections elsewhere in Sweden as well as Norway,

Estonia, Denmark and Great Britain. The

<2 μm clay fraction of the Osmundsberg bed contains

abundant kaolinite in addition to randomly ordered

(RO) illite/smectite (I/S). Modelling of the X-ray

diffraction tracings showed the I/S consists of 18% illite

and 82% smectite. The high smectite and kaolinite content is

indicative of a history with minimal burial

temperatures. Analytical data from both pristine melt inclusions

in primary quartz grains as well as whole

rock samples can be used to constrain both the parental magma

composition and the probable tectonic setting

of the source volcanoes. The parental ash was dacitic to

rhyolitic in composition and originated in a tectonically

active collision margin setting.

Whole rock chemical fingerprinting of coeval beds elsewhere

in Baltoscandia produced a pronounced

clustering of these samples in the Osmundsberg field of the

discriminant analysis diagram. This, together

with well-constrained biostratigraphic and lithostratigraphic

data, provides the basis for regional correlation

and supports the conclusion that the Osmundsberg K-bentonite is

one of the most extensive fallout ash beds

in the early Phanerozoic. The source volcano probably lay to

the west of Baltica as part of the subduction

complex associated with the closure of Iapetus.
A petrological and fluid inclusion study of

calc-silicate–charnockite associations from southern Kerala,

India: implications for CO2 influx
Authors: SATISH-KUMAR M. , SANTOSH M.
Published: July 2002

Recent discovery of wollastonite-bearing calc-silicate

assemblages adjacent to

gneiss–charnockite horizons in the supracrustal terrain

of the Kerala Khondalite Belt, southern India, provides

an opportunity to evaluate the carbonic fluid infiltration

model proposed for charnockite formation.

Petrological and fluid inclusion studies across these horizons

in three representative localities are presented

in this study. The calc-silicate assemblages define peak

metamorphic conditions of ∼800°C at 5 kbar and

define a low aCO2. Adjacent

charnockite assemblages

developed through dehydration involving the breakdown

of garnet, biotite and quartz to produce orthopyroxene under

low aH2O conditions. Retrograde

reactions preserved in the calc-silicate rocks, such as

scapolite–quartz symplectites, and the partial breakdown

of wollastonite previously has been attributed to a near

isothermal decompression during which infiltration

of CO2-rich fluids occurred. Fluid inclusion

studies indicate that the earliest generation of fluids

preserved in the calc-silicate assemblages are aqueous (with

salinity ∼8 wt% NaCl equivalent), consistent with mineral

phase equilibria defining low aCO2.

The estimation of NaCl content in brines coexisting with scapolite,

based on the Cl content of the scapolite, indicates the presence of

up to 20 wt % NaCl during the formation of

scapolite consistent with the saline primary fluid inclusions.

Primary carbonic inclusions occur within the

retrogressed calcite+quartz assemblage after wollastonite,

and are considered to represent the post-peak

metamorphic carbonic fluid infiltration event, synchronous

with the development of charnockites in the

adjacent gneisses. These inclusions have identical

characteristics to those in the charnockites. We envisage

that the Kerala Khondalite Belt fluid regime was largely

internally buffered during the prograde path, and

that CO2 infiltration post-dated peak metamorphism.

Influx of CO2 was mostly structurally controlled, and

occurred along a near-isothermal uplift path. Graphite-bearing

pegmatitic dykes with abundant CO2-rich

inclusions in these localities attest to the transfer of

carbonic fluids through magmatic conduits.
Pre-lamprophyre mafic dykes of the Cape Meredith Complex,
West Falkland
Authors: THOMAS R. J. , HENJES-KUNST F. , JACOBS J.
Published: July 2002

New field, petrographic, geochemical and Rb–Sr/Sm–Nd

isotope data are presented from
early mafic dykes which intrude the Mesoproterozoic Cape Meredith Complex,
West Falkland. The
dykes, which have been previously regarded as being Ordovician
in age, are seen in the field to cut
a suite of lamprophyre sheets. New K–Ar data from biotite
separates from two lamprophyres suggest
a miminum age of emplacement of ∼520 Ma, confirming previous work.
The Rb–Sr
and Sm–Nd analyses of the pre-lamprophyre mafic dykes suggests that

they were probably intruded during the late
Neoproterozoic at ∼600 Ma. This new data has considerable
implications for the previously published
estimates of the longevity of intracontinental extension events in this
part of Gondwana.
Table Nunatak: a key outcrop of Upper Cretaceous shallow-marine
strata in the southern Larsen Basin, Antarctic Peninsula
Authors: HATHWAY B. , MACDONALD D. I. M. , RIDING J. B. , CANTRILL D. J.
Published: July 2002

The northern, James Ross Island region of the Larsen Basin, on
the eastern, back-arc margin
of the Antarctic Peninsula magmatic arc, includes one of the thickest and
most complete Upper
Cretaceous sedimentary successions exposed in the Southern Hemisphere.
However, the southern part
of the basin remains poorly known, mainly owing to inaccessibility and
lack of exposure. Table
Nunatak, an isolated, 1-km-long, 400-m-wide outcrop at the tip of Kenyon
Peninsula, is the only
known exposure of Upper Cretaceous or younger strata in this region. The
62-m-thick succession
exposed there is assigned to the newly defined Table Nunatak Formation.
It consists mainly of sharp-based,
amalgamated beds of fine-grained sandstone up to 2.8 m thick, with subordinate
intervals of
intensely bioturbated mudstone. Wave ripples are present at some levels,
and locally developed swaley
cross-stratification provides evidence for storm-generated combined-flow
deposition. However, most
sandstone beds appear to be internally structureless apart from normal
grading, and are interpreted as
the direct suspension deposits of highly sediment-charged storm-
and/or flood-related flows. The succession
represents relatively nearshore deposition, probably at the mouth of
a river or deltaic distributary
channel. Charcoalified plant debris, abundant at the tops of some sandstone
beds, suggests a
periodically wildfire-swept hinterland forested largely by coniferous
trees. Dinoflagellate cyst assemblages
indicate a late Santonian age, and suggest correlation with the basal part
of the Lachman Crags
Member of the Santa Marta Formation (Marambio Group) on James Ross Island.
Palaeocurrents,
sandstone petrography and the high sediment supply rate proposed
for the Table Nunatak Formation,
suggest a relatively high-relief source area to the west, with
large-scale erosion of granitoid plutons
and metamorphic rocks, possibly related to arc uplift during a
mid-Cretaceous compressional episode.
The formation is evidence of a major southward extension of the
Upper Cretaceous strata exposed in
the northern Larsen Basin, and suggests lateral continuity of
shallow-marine deposition for at least
500–600 km along the Weddell Sea margin of the Antarctic Peninsula
in Santonian times.
Rb–Sr isotope studies on Tinos Island (Cyclades, Greece):
additional time constraints for metamorphism, extent of
infiltration-controlled overprinting and deformational activity
Authors: BRÖCKER MICHAEL , FRANZ LEANDER
Published: July 2002

This study presents new Rb–Sr age data concerning the metamorphic

evolution of the Attic-Cycladic
Crystalline Belt which represents a complex polymetamorphic terrane within
the Alpidic orogenic
belt of the Hellenides. Two major groups of tectonic units can be
distinguished. Metamorphism in parts of
the upper units is commonly considered as a Cretaceous event. In contrast,

the group of lower units experienced
Tertiary high-pressure metamorphism which was followed by a medium-pressure
overprint. We focus
on the island of Tinos where a representative spectrum of the rock
units found in the Cyclades is exposed in
three tectonic units: the Upper Unit, the Intermediate Unit and the
Basal Unit. The complete range of
tectono-metamorphic and magmatic events affecting the Attic-Cycladic
Crystalline Belt is documented by
numerous petrological and tectonic studies. Phyllites and phyllonites
from the ophiolitic Upper Unit yielded
Rb–Sr apparent ages (phengite–whole-rock) between
c. 92 and 21 Ma. The older age differs from the
Cretaceous dates reported for upper unit rocks elsewhere in the
Cyclades. It is suggested that the sequence
studied belongs to the Jurassic ophiolites of the Hellenides rather
than to Cretaceous occurrences. The
spread to younger ages is related to non-pervasive rejuvenation and
resetting of the Rb–Sr system during
tectonic juxtaposition of the Upper Unit over the Intermediate Unit.
The youngest age obtained so far for a
sample from the Upper Unit (21 Ma) is believed to approximate the
timing of tectonic juxtaposition which
probably occurred during a regional greenschist-facies episode
producing a pervasive overprint in the structurally
lower tectonic unit. The major phyllite/meta-gabbro/serpentinite

sequence of the Upper Unit is interpreted
as an emplacement-related ductile shear zone which experienced
reworking under brittle conditions.
In the Intermediate Unit, a gradient in Rb–Sr ages from top
(c. 40 Ma) to the bottom (c. 22 Ma) was recognized,
which is interpreted to represent greater effects of fluid infiltration

and overprinting in the lower parts
of this unit, possibly controlled by variable intensity of deformation

which might be related to tectonic juxtaposition
onto the Basal Unit. We suggest that synmetamorphic stacking of all three
tectonic units took
place during an Oligocene–Miocene greenschist event.
Extensional deformation continued after tectonic
stacking and after intrusion of the main granite, as is indicated
by a Rb–Sr whole-rock isochron (15.1∓0.6 Ma) for a ductilely

deformed garnet-bearing leucogranite from the marginal parts of the main
undeformed
pluton. Application of the Rb–Sr dating technique provided no
unequivocal evidence that previously published
Eocene K–Ar and 40Ar–39Ar dates for high-pressure
phengites
from the lower units are significantly contaminated with excess argon.
New uppermost Cambrian U–Pb date from Avalonian Wales
and age of the Cambrian–Ordovician boundary
Authors: DAVIDEK K. , LANDING E. , BOWRING S. A. , WESTROP S. R. , RUSHTON A. W. A. , FORTEY R. A. , ADRAIN J. M.
Published: July 2002

A crystal-rich volcaniclastic sandstone in the lower Peltura

scarabaeoides Zone at Ogof-ddû
near Criccieth, North Wales, yields a U–Pb zircon age of 491∓1
Ma.
This late Late Cambrian date indicates
a remarkably young age for the Cambrian–Ordovician boundary whose

age must be less than 491 Ma.
Hence the revised duration of the post-Placentian (trilobite-bearing)
Cambrian indicates that local trilobite
zonations allow a biostratigraphic resolution comparable to that provided

by Ordovician graptolites and Mesozoic ammonites.
A Vendian–Cambrian boundary succession from the
northwestern margin of the Siberian Platform: stratigraphy,
palaeontology, chemostratigraphy and correlation
Authors: BARTLEY JULIE K. , POPE MICHAEL , KNOLL ANDREW H. , SEMIKHATOV MIKHAIL A. , PETROV PETER YU.
Published: July 2002

Siberia contains several key reference sections for studies of

biological and environmental
evolution across the Proterozoic–Phanerozoic transition. The
Platonovskaya Formation, exposed in the
Turukhansk region of western Siberia, is an uppermost Proterozoic to Cambrian
succession whose
trace and body fossils place broad limits on the age of deposition,
but do not permit detailed correlation
with boundary successions elsewhere. In contrast, a striking negative
carbon isotopic excursion in the
lower part of the Platonovskaya Formation permits precise
chemostratigraphic correlation with uppermost
Yudomian successions in Siberia, and possibly worldwide. In addition
to providing a tool for correlation,
the isotopic excursion preserved in the Platonovskaya and contemporaneous
successions
documents a major biogeochemical event, likely involving the world
ocean. The excursion coincides
with the palaeontological breakpoint between Ediacaran- and
Cambrian-style assemblages, suggesting
a role for biogeochemical change in evolutionary events near the
Proterozoic–Cambrian boundary.
The Early Carboniferous (Courceyan–Arundian)
monsoonal climate of the British Isles: evidence from growth
rings in fossil woods
Authors: FALCON-LANG H. J.
Published: July 2002

The British Isles lay at a palaeolatitude of 4°S during the
Early Carboniferous
(Courceyan–Arundian) period. This paper examines fossil gymnosperm
wood from ten localities in
western Ireland and southern Scotland in order to analyse palaeoclimate.
Fifty-two percent of the 77
fossil wood specimens studied exhibit growth rings that possess subtle,
discontinuous ring boundaries
and ring increments of narrow but variable width. These growth rings are
qualitatively and quantitatively
analysed, and are shown to bear a close similarity to growth rings in modern
araucarian conifer
woods; these araucarian growth rings are formed in response to tropical
rainfall seasonality linked
to monsoonal circulation. The findings of this study therefore support
earlier palaeoclimatic interpretations,
based on sedimentological evidence, which suggest that the British Isles
experienced a
monsoonal climate during the Early Carboniferous (Courceyan–Arundian)
period.
Using basement-hosted clastic dykes as syn-rifting palaeostress
indicators: an example from the basal Stoer Group, northwest
Scotland
Authors: BEACOM L. E. , ANDERSON T. B. , HOLDSWORTH R. E.
Published: July 2002

Clastic infills of fractures (here termed clastic veins) in basement rocks immediately underlying
sedimentary cover sequences can be used to date fault movements if these demonstrably
occurred at the time of infilling or prior to the lithification of the entrained clastic material. This
allows reconstruction of the syn-rifting palaeostress system using stress inversion techniques. During
Riphean intracontinential rifting of Laurentia, the Torridonian Stoer Group sediments of northwest
Scotland were deposited in half-graben basins controlled by faults, e.g. the Coigach and Clachtoll
faults. At Clachtoll, northeast–southwest oblique sinistral normal faulting in the underlying basement
is associated with extensive development of shear, hybrid and tensile clastic veins filled with Stoer
Group sediment, infilled and deformed prior to sediment lithification. Clastic veins initially formed by
gravitational infilling of sediment from above, followed by tectonically-driven, forceful hydraulic injection
of fluidized sand into new fractures and reactivated pre-existing basement faults. Palaeostress
axes, determined from fault lineation data and tensile fracture extension directions in the Clachtoll
Fault zone, indicate west-northwest–east-southeast directed extension during rifting. On a regional
scale, this implies oblique-dextral extension on the north- to north-northeast-trending Coigach Fault
during Stoer Group deposition. Similar orientations, age relationships and kinematics have been
obtained from pre-Torridon Group fault arrays developed in the Lewisian basement near Gairloch
and Loch Maree. Overall, the faulting patterns reflect a three-dimensional strain (k≠1) formed by
east-southeast–west-northwest-directed extension during deposition of the Stoer Group. More speculatitively,
asymmetric density patterns of sinistral and dextral faults may indicate that rifting occurred
in a regional zone of broadly north–south-oriented dextral transtension.
Broad bean and lentil seed treatments with

imidazolinones for the control of broomrape

(Orobanche crenata)
Authors: JURADO-EXPÓSITO M. , GARCÍA-TORRES L. , CASTEJÓN-MUÑOZ M.
Published: July 2002

Studies were conducted from 1993 to 1995 in Southern Spain to

determine the feasibility of

controlling broomrape (Orobanche crenata Forsk.) in

broad bean (Vicia faba L.) and lentil (Lens

culinaris L.) by treating seeds with imazethapyr and imazapyr. In

the broad bean, soaking for 5 min

in 0·01–0·1% herbicide solutions or coating at

20–40 g ha−1 (seed sowing rate 160 kg

ha−1) with

imazethapyr (Pursuit-10) did not affect seed germination and crop growth,

and resulted in 60–80%

broomrape control. Furthermore, broad bean seeds treated with imazethapyr

followed by an

additional late post-emergence application of imazapyr (Arsenal-25) at

5 g ha−1 resulted in excellent

broomrape control (>95%). Similarly, lentil seed treatments with

imazapyr by coating seeds at rates equivalent to 5–10 g ha−1

or by soaking for 5 min in 0·25% solutions did not affect germination

or crop growth, and controlled 85–95% of broomrape.

As a result, with broomrape-efficient

herbicide treatments, crop biomass/seed yield increased

as compared to broomrape-infested, non-treated controls.

Herbicide seed treatments with imazapyr in broad bean and with imazethapyr
in

lentil were less well tolerated and were less effective in

controlling broomrape than treatments with

imazethapyr and imazapyr, respectively.
Plant uptake of nitrogen from the organic nitrogen
fraction of animal manures: a laboratory experiment
Authors: CHADWICK D. R. , JOHN F. , PAIN B. F. , CHAMBERS B. J. , WILLIAMS J.
Published: July 2002

Twenty slurries, 20 farmyard manures (FYM) and 10 poultry manures were chemically analysed to
characterize their nitrogen (N) fractions and to assess their potential organic N supply. The organic
N fraction varied between manure types and represented from 14% to 99% of the total N content.
The readily mineralizable N fraction, measured by refluxing with KCl, was largest in the pig FYMs
and broiler litters, but on average only represented 7–8% of the total N content. A pot experiment
was undertaken to measure N mineralization from the organic N fraction of 17 of these manures. The
ammonium-N content of the manures was removed and the remaining organic N mixed with a low
mineral N status sandy soil, which was sown with perennial ryegrass (Lolium perenne L.). N offtake
was used as a measure of mineralization throughout the 199 day experiment. The greatest N
mineralization was measured from a layer manure and a pig slurry, where N offtake represented 56%
and 37% of the organic N added, respectively. Lowest (%) N mineralization was measured from a
dairy cow slurry (< 2%) and a beef FYM (6%). The mineralization rate was negatively related to
the C[ratio ]organic N ratio of the ammonium-N stripped manures (P < 0·01, r = −0·63).
HYSTERECTOMY IS ASSOCIATED WITH POSTMENOPAUSAL BODY COMPOSITION CHARACTERISTICS
Authors: KIRCHENGAST SYLVIA , GRUBER DORIS , SATOR MICHAEL , HUBER JOHANNES
Published: July 2002

The impact of hysterectomy without oophorectomy and with no malignant purpose on body composition and postmenopausal weight gain was tested in 184 Viennese females aged between 47 and 57 years (mean 52·9). Hysterectomized women were significantly heavier than those who experienced a spontaneous menopause (controls). The amount of fat tissue, especially in the abdominal region, was significantly higher in hysterectomized women. Furthermore, they were reported to have experienced a significantly higher weight gain since menopause (9·1 versus 6·0 kg). No significant differences in bone mass were found. Psychological stress factors and hormonal changes following hysterectomy are discussed as possible causes of these differences.
Modification of microstructure and texture of rennet curd by using
a
capsule-forming non-ropy lactic culture
Authors: HASSAN ASHRAF N. , FRANK JOSEPH F.
Published: July 2002

Microstructural and textural characteristics of rennet curd made
from
rehydrated non-fat dried milk standardized to 40 g fat/l
were compared with those
of non-fat curd made with capsule-forming non-ropy lactic culture. Microstructure

examination using confocal scanning laser microscopy indicated that the
presence of
a capsule-forming culture produced an open casein network with large pores.

Distribution of fat globules was observed within the undisturbed casein
structure
after staining with a fluorescent lipophilic dye which was added to the
milk before
coagulation. Bacterial capsules and milk fat reduced curd tension and firmness
of
rennet curd to similar levels.
Quantitative secretion and maximal secretion capacity of retinol,
β-carotene and α-tocopherol into cows' milk
Authors: JENSEN SØREN KROGH , JOHANNSEN ANNA KIRSTIN BJØRNBAK , HERMANSEN JOHN E.
Published: July 2002

Changes in the contents of retinol, α-tocopherol and β-carotene in plasma,
milk and milk fat from 38 Holstein–Friesian cows were followed during their first
lactation, and the quantitative and kinetic relationships for secretion of α-tocopherol
and β-carotene from blood into milk were determined. The cows were assigned to
three groups such that all cows in the same group had the same sire. Milk yield and
milk fat content differed with stage of lactation, but not according to sire. The
plasma concentrations of retinol, α-tocopherol and β-carotene differed with stage of
lactation; in addition, retinol and β-carotene concentration also differed according to
sire. The concentrations of all three vitamins in milk and milk fat differed according
to sire and stage of lactation. Furthermore, the total secretion of retinol,
α-tocopherol and β-carotene into milk (expressed as mg/d) differed with sire and stage
of lactation. The quantitative secretion of α-tocopherol and β-carotene from blood
into milk followed Michaelis–Menten kinetics for active transport across membranes.
Values of maximum secretory capacity Vmax and the half-rate
constant Km for both
α-tocopherol and β-carotene varied according to sire.
Overall means for Vmax for
α-tocopherol and β-carotene were 32·4 and 27·5 mg/d.
Thus, the daily secretion of α-tocopherol and β-carotene is limited in quantity,
and is independent of the yields of
milk and milk fat. It follows that continuing breeding and management systems that
focus solely on increasing milk and milk fat yield will result in a steady dilution in
the milk fat of these vitamins and antioxidants important for the immune defence
of the cows and oxidative stability of milk products. The genetic variation found
offers the possibility of utilizing these variations in breeding systems.
Influence of ions on growth and production of exopolysaccharides
by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772
Authors: GROBBEN GERT J. , BOELS INGEBORG C. , SIKKEMA JAN , SMITH MARK R. , DE BONT JAN A. M.
Published: July 2002

Several lactic acid bacteria produce exopolysaccharides (EPS), either attached to
the cell wall or excreted into the environment as slime material. EPS produced by
Lactobacillus delbrueckii subsp. bulgaricus (Lb. bulgaricus)
and Streptococcus thermophilus play an important role in improving the texture and stability of yogurt
and preventing syneresis (Cerning, 1990; Nakajima et al. 1990). The amount and
composition of the EPS produced by lactic acid bacteria are dependent on a number
of factors, such as temperature, initial pH, carbon source and the availability of
minerals, vitamins and other medium components.

In previous work it was shown that the production and sugar composition of the
EPS from Lb. bulgaricus NCFB2772 are affected by the carbohydrate source (Grobben
et al. 1995, 1996). In a simplified defined medium, from which several vitamins and
trace elements were omitted, EPS production by Lb. bulgaricus significantly
increased, although growth of the strain was reduced (Grobben et al. 1998).
Flow physics of discrete boundary layer suction – measurements and predictions
Authors: MacMANUS D. G. , EATON J. A.
Published: July 2002

The primary objective of this work is to determine the detailed characteristics of
the flow features induced in a boundary layer by suction through laminar flow control
(LFC) perforations. An additional goal is to validate a predictive method for
generic LFC suction surfaces and to apply this technique to typical flight condition
configurations. Fundamental insights into the flow physics of LFC suction surfaces
are obtained from a unique series of high-resolution three-component laser Doppler
velocimetry (LDV) flow field measurements. The flow fields induced by isolated
super-scale perforations under low-speed conditions are mapped and found to be
strongly three-dimensional and profoundly different from the idealized concept of
continuously distributed suction. Over a range of sub- and super-critical suction flow
rates a variety of suction-dependent complex flow features are identified, including a
pair of contra-rotating streamwise vortices, multiple co-rotating streamwise vortices,
spanwise variations of the mean flow and inherently unstable boundary layer profiles.
The measurements reveal that suction-induced transition commences with an
instability of these attached vortices, resulting in the development of a pair of turbulent
wedges downstream of the perforation. A finite-volume Navier–Stokes method
is validated by simulating a variety of low-speed experiments and comparisons are
made between the LDV measurements and the predicted flow field. The computational technique
reproduces all of the observed flow features, although it slightly
under-predicts their magnitude and extent. By analysing the predicted flow fields the
mechanism for the formation of the trailing vortex pair is established. Earlier flow
visualization experiments, which exhibited vortex shedding, are also simulated by
solving the time-dependent governing equations and it is found that the principal unsteady
flow features are captured. Despite the challenge posed to the computational
method by the diverse range of flow phenomena induced by discrete suction, the
predictions provide good agreement with the measurements and observations. The
computational tool is subsequently applied to predict the flow fields of single and
multiple rows of actual-scale micro-perforations under low-speed and typical transonic
flight conditions. A range of suction-induced flow features are predicted and a
variety of distinct flow modes are identified. The low-speed critical suction limits are
also measured and a design criterion, based on the sucked streamtube characteristics,
is established. The basis of this critical suction criterion is also validated for transonic
flight configurations.
Numerical simulation of convection and heat transfer in water absorbing solar radiation
Authors: VEREVOCHKIN YU. G. , STARTSEV S. A.
Published: July 2002

Thermal convection in a horizontal water layer being cooled from above and absorbing
solar radiation is simulated numerically at the Prandtl number Pr = 7. Three
different regimes arising are investigated here. The first is characterized by intermittent
convection, the second by steady-state convection, and the third is convection
free. The transitions occur at different values of J0/Q, the ratio of downward solar-radiation flux just below the surface to heat flux through the interface (assumed to be
constant), but at almost the same Rayleigh number. The generalized heat-conduction
law is found to be valid.
An experimental investigation of the relative diffusion of particle pairs in three-dimensional turbulent flow
Authors: OTT SØREN , MANN JAKOB
Published: July 2002

The particle tracking (PT) technique is used to study turbulent diffusion of particle
pairs in a three-dimensional turbulent flow generated by two oscillating grids. The
experimental data show a range where the Richardson–Obukhov law
〈r2〉 = Cεt3 is
satisfied, and the Richardson–Obukhov constant is found to be C = 0.5. A number of
models predict much larger values. Furthermore, the distance–neighbour function is
studied in detail in order to determine its general shape. The results are compared with
the predictions of three models: Richardson (1926), Batchelor (1952) and Kraichnan
(1966a). These three models predict different behaviours of the distance–neighbour
function, and of the three, only Richardson's model is found to be consistent with the
measurements. We have corrected a minor error in Kraichnan's (1996a) Lagrangian
history direct interaction calculations with the result that we had to increase his
theoretical value from C = 2.42 to C = 5.5.
Flow past a square-section cylinder with a wavy stagnation face
Authors: DAREKAR RUPAD M. , SHERWIN SPENCER J.
Published: July 2002

Numerical investigations have been performed for the flow past square-section cylinders
with a spanwise geometric deformation leading to a stagnation face with a
sinusoidal waviness. The computations were performed using a spectral/hp element
solver over a range of Reynolds numbers from 10 to 150.

Starting from fully developed shedding past a straight cylinder at a Reynolds
number of 100, a sufficiently high waviness is impulsively introduced resulting in
the stabilization of the near wake to a time-independent state. It is shown that
the spanwise waviness sets up a cross-flow within the growing boundary layer on
the leading-edge surface thereby generating streamwise and vertical components
of vorticity. These additional components of vorticity appear in regions close to the
inflection points of the wavy stagnation face where the spanwise vorticity is weakened.
This redistribution of vorticity leads to the breakdown of the unsteady and staggered
Kármán vortex wake into a steady and symmetric near-wake structure. The steady
nature of the near wake is associated with a reduction in total drag of about 16% at
a Reynolds number of 100 compared with the straight, non-wavy cylinder.

Further increases in the amplitude of the waviness lead to the emergence of hairpin
vortices from the near-wake region. This wake topology has similarities to the wake
of a sphere at low Reynolds numbers. The physical structure of the wake due to
the variation of the amplitude of the waviness is identified with five distinct regimes.
Furthermore, the introduction of a waviness at a wavelength close to the mode A
wavelength and the primary wavelength of the straight square-section cylinder leads
to the suppression of the Kármán street at a minimal waviness amplitude.
Direct simulation of turbulent supersonic boundary layers by an extended temporal approach
Authors: MAEDER THIERRY , ADAMS NIKOLAUS A. , KLEISER LEONHARD
Published: July 2002

The present paper addresses the direct numerical simulation of turbulent
zero-pressure-gradient boundary layers on a flat plate at Mach numbers 3, 4.5 and 6
with momentum-thickness Reynolds numbers of about 3000. Simulations are performed
with an extended temporal direct numerical simulation (ETDNS) method.
Assuming that the slow streamwise variation of the mean boundary layer is governed
by parabolized Navier–Stokes equations, the equations solved locally in time with a
temporal DNS are modified by a distributed forcing term so that the parabolized
Navier–Stokes equations are recovered for the spatial average. The correct mean flow
is obtained without a priori knowledge, the streamwise mean-flow evolution being
approximated from its upstream history. ETDNS reduces the computational effort by
up to two orders of magnitude compared to a fully spatial simulation.

We present results for a constant wall temperature Tw chosen to be equal to
its laminar adiabatic value, which is about 2.5 T∞,
4.4 T∞ and 7 T∞, respectively,
where T∞ is the free-stream temperature for the three Mach numbers considered.
The simulations are initialized with transition-simulation data or with re-scaled
turbulent data at different parameters. We find that the ETDNS results closely match
experimental mean-flow data. The van Driest transformed velocity profiles follow the
incompressible law of the wall with small logarithmic regions.

Of particular interest is the significance of compressibility effects in a Mach number
range around the limit of M∞ ≃ 5, up to which Morkovin's hypothesis is believed
to be valid. The results show that pressure dilatation and dilatational dissipation
correlations are small throughout the considered Mach number range. On the other
hand, correlations derived from Morkovin's hypothesis are not necessarily valid, as is
shown for the strong Reynolds analogy.
‘Phase diagram’ of interfacial instabilities in a
two-layer Couette flow and mechanism of the long-wave instability
Authors: CHARRU FRANÇOIS , HINCH E. JOHN
Published: July 2002

A unified view is given of the instabilities that may develop in two-layer Couette
flows, as a ‘phase diagram’ in the parameter space. This view is obtained from a
preliminary study of the single-fluid Couette flow over a wavy bottom, which reveals
three flow regimes for the disturbances created at the bottom, each regime being
characterized by a typical penetration depth of the vorticity disturbances and an
effective Reynolds number. It appears that the two-layer flow exhibits the same flow
regimes for the disturbances induced by the perturbed interface, and that each type
of instability can be associated with a flow regime. Typical curves giving the growth
rate versus wavenumber are deduced from this analysis, and favourably compared
with the existing literature. In the second part of this study, we propose a mechanism
for the long wavelength instability, and provide simple estimates of the wave velocity
and growth rate, for channel flows and for semi-bounded flows. In particular, an
explanation is given for the ‘thin-layer effect’, which is typical of multi-layer flows
such as pressure driven flows or gravity driven flows, and according to which the flow
is stable if the thinner layer is the less viscous, and unstable otherwise.
Langmuir turbulence in the ocean
Authors: McWILLIAMS JAMES C. , SULLIVAN PETER P. , MOENG CHIN-HOH
Published: July 2002

Solutions are analysed from large-eddy simulations of the phase-averaged

equations for oceanic currents in the surface planetary boundary layer
(PBL),

where the averaging is over high-frequency surface gravity waves. These
equations

have additional

terms proportional to the Lagrangian Stokes drift of the waves, including
vortex

and Coriolis forces and tracer advection. For the wind-driven PBL, the
turbulent

Langmuir number, Latur =

(U∗/Us)1/2,
measures

the relative influences of directly

wind-driven shear (with friction velocity U∗) and the Stokes
drift

Us. We focus on

equilibrium solutions with steady, aligned wind and waves and a realistic

Latur = 0.3.

The mean current has an Eulerian volume transport to the right of the wind
and

against the Stokes drift. The turbulent vertical fluxes of momentum and
tracers are

enhanced by the presence of the Stokes drift, as are the turbulent kinetic

energy and its dissipation and the skewness of vertical velocity. The dominant

coherent structure in the turbulence is a Langmuir cell, which has its

strongest vorticity aligned longitudinally (with the wind and waves) and

intensified near the surface on the scale of the

Stokes drift profile. Associated with this are down-wind surface convergence
zones

connected to interior circulations whose horizontal divergence axis is
rotated about

45° to the right of the wind. The horizontal scale of the Langmuir
cells

expands with depth, and there are also intense motions on a scale finer
than

the dominant cells very near the surface. In a turbulent PBL, Langmuir
cells

have irregular patterns with finite correlation scales in space and time,
and

they undergo occasional mergers in the vicinity of Y-junctions between

convergence zones.
The propagation of premixed flames in closed tubes
Authors: MATALON MOSHE , METZENER PHILIPPE
Published: July 2002

A nonlinear evolution equation that describes the propagation of
a

premixed flame

in a closed tube has been derived from the general conservation equations.
What

distinguishes it from other similar equations is a memory term whose origin
is in

the vorticity production at the flame front. The two important parameters
in this

equation are the tube's aspect ratio and the Markstein parameter.
A linear

stability

analysis indicates that when the Markstein parameter α is above a
critical

value αc the

planar flame is the stable equilibrium solution. For α below

αc the planar flame is no

longer stable and there is a band of growing modes. Numerical solutions
of the full

nonlinear equation confirm this conclusion. Starting with random initial
conditions

the results indicate that, after a short transient, a at flame develops
when

α>αc and it remains flat until it reaches the end of the tube. When

α<αc, on the other hand,

stable curved flames may develop down the tube. Depending on the initial
conditions

the flame assumes either a cellular structure, characterized by a finite
number of

cells convex towards the unburned gas, or a tulip shape characterized by
a sharp

indentation at the centre of the tube pointing toward the burned gases.
In

particular, if the initial conditions are chosen so as to simulate the
elongated

finger-like flame

that evolves from an ignition source, a tulip flame evolves downstream.
In accord

with experimental observations the tulip shape forms only after the flame

has travelled a

certain distance down the tube, it does not form in short tubes and its
formation

depends on the mixture composition. While the initial deformation of the
flame

front is a direct result of the hydrodynamic instability, the actual formation

of the tulip flame results from the vortical motion created in the burned
gas

which is a consequence of the vorticity produced at the flame front.