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The increasing comorbidity of alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) associated with traumatic brain injury (TBI) is a serious medical, economic, and social issue. However, the molecular toxicology and pathophysiological mechanisms of comorbid AUD and PTSD are not well understood and the identification of the comorbidity state markers is significantly challenging. This review summarizes the main characteristics of comorbidity between AUD and PTSD (AUD/PTSD) and highlights the significance of a comprehensive understanding of the molecular toxicology and pathophysiological mechanisms of AUD/PTSD, particularly following TBI, with a focus on the role of metabolomics, inflammation, neuroendocrine, signal transduction pathways, and genetic regulation. Instead of a separate disease state, a comprehensive examination of comorbid AUD and PTSD is emphasized by considering additive and synergistic interactions between the two diseases. Finally, we propose several hypotheses of molecular mechanisms for AUD/PTSD and discuss potential future research directions that may provide new insights and translational application opportunities.

The deeply eroded Acraman structure in the Mesoproterozoic Gawler Range Volcanics, Gawler Craton, South Australia, ranks among the world’s largest known impact structures, with a transient crater ∼...

With aging, the nervous system gradually undergoes degeneration. Increased oxidative stress, endoplasmic reticulum stress, mitochondrial dysfunction, and cell death are considered to be common pathophysiological mechanisms of various neurodegenerative diseases (NDDs) such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), organophosphate-induced delayed neuropathy (OPIDN), and amyotrophic lateral sclerosis (ALS). Autophagy is a cellular basic metabolic process that degrades the aggregated or misfolded proteins and abnormal organelles in cells. The abnormal regulation of neuronal autophagy is accompanied by the accumulation and deposition of irregular proteins, leading to changes in neuron homeostasis and neurodegeneration. Autophagy exhibits both a protective mechanism and a damage pathway related to programmed cell death. Because of its “double-edged sword”, autophagy plays an important role in neurological damage and NDDs including AD, PD, HD, OPIDN, and ALS. Melatonin is a neuroendocrine hormone mainly synthesized in the pineal gland and exhibits a wide range of biological functions, such as sleep control, regulating circadian rhythm, immune enhancement, metabolism regulation, antioxidant, anti-aging, and anti-tumor effects. It can prevent cell death, reduce inflammation, block calcium channels, etc. In this review, we briefly discuss the neuroprotective role of melatonin against various NDDs via regulating autophagy, which could be a new field for future translational research and clinical studies to discover preventive or therapeutic agents for many NDDs.

The late Ediacaran Shuram–Wonoka excursion, with δ13Ccarb values as low as –12‰ (PDB) in marine-shelf deposits and spanning up to 10 Myr, is the deepest and most protracted δ13Ccarb negative anomaly recognised in Earth history. The excursion formed on at least four continents in low (≤32°) palaeolatitudes, and in China is associated with a major phosphogenic event. Global and intrabasinal correlation, magnetostratigraphy, isotope conglomerate tests and further geochemical data are consistent with a primary or syn-depositional origin for the excursion. Continental-margin phosphorites are generated by oceanic upwelling driven by surface winds, and δ13Ccarb negative anomalies are explicable by oceanic upwelling of 13C-depleted deep oceanic waters, arguing that a feature common to these exceptional Ediacaran events was unprecedented perturbation of the world ocean. These events occurred during the transition from an alien Proterozoic world marked by low-palaeolatitude glaciation near sea level and strong seasonality to the familiar Phanerozoic Earth with circum-polar glaciation and temperate climate, suggesting that the Shuram–Wonoka excursion is related to this profound change in Earth's climate system. Of various hypotheses for Proterozoic low-palaeolatitude glaciation, only the high obliquity (>54°) hypothesis, which posits secular decrease in obliquity to near the present-day value (23.5°) during the Ediacaran, predicts an unparalleled revolution in the Ediacaran world ocean. The obliquity controls the sense of the world ocean's meridional overturning circulation, which today is driven by the sinking of cold, dense water at the poles and upwelling driven by zonal surface winds. When the decreasing obliquity passed the critical value of 54° during the Ediacaran the meridional temperature gradient reversed, with the equator becoming warmer than the poles and Hadley low-latitude (

During the Mesozoic and Paleogene, the Precambrian rocks in the Pilbara, Western Australia, underwent erosion and deep weathering that produced an undulating landform now represented by the duricrusted and partly eroded Hamersley Surface. A reddened, ferruginous weathering zone occurs immediately beneath this duricrusted surface. Oriented block samples of ferruginised strata of the Neoarchean–early Paleoproterozoic Hamersley Group exposed within approximately 15 m below the duricrust were collected at 20 sites in roadcuts along the Great Northern Highway between Munjina and Newman and exposures along the adjoining Karijini Drive. Stepwise thermal demagnetisation of cored specimens revealed a stable, high-temperature (680°C) component carried by hematite, with a mean direction (n = 55 specimens) of declination D = 182.0°, inclination I = 52.9° (α95 = 3.6°), indicating a pole position at latitude λp = 77.6°S, longitude ϕp = 113.2°E (A95 = 4.3°) and a paleolatitude λ = 33.5 +3.6/–3.3°S. Both normal a...

Proterozoic (pre-Ediacaran) glaciations occurred under strongly seasonal climates near sea level in low palaeolatitudes. Metre-scale primary sand wedges in Cryogenian periglacial deposits are identical to those actively forming, through the infilling of seasonal (winter) thermal contraction-cracks in permafrost by windblown sand, in present-day polar regions with a mean monthly air temperature range of 40 °C and mean annual air temperatures of −20 °C or lower. Varve-like rhythmites with dropstones in Proterozoic glacial successions are consistent with an active seasonal freeze–thaw cycle. The seasonal (annual) oscillation of sea level recorded by tidal rhythmites in Cryogenian glacial successions indicates a significant seasonal cycle and extensive open seas. Palaeomagnetic data determined directly for Proterozoic glacial deposits and closely associated rocks indicate low palaeolatitudes: Cryogenian deposits in South Australia accumulated at ≤10°, most other Cryogenian deposits at 54°) during Proterozoic low-latitude glaciations, whereby the equator would be cooler than the poles, on average, and global seasonality would be greatly amplified.

New paleomagnetic data for red beds (dolomitic siltstone and fine-grained sandstone) from the Angepena Formation of the late Cryogenian interglacial succession between deposits of the Sturt glaciation (ca 660 Ma) and Elatina glaciation (ca 635 Ma) in the Adelaide Geosyncline, South Australia, together with previous paleomagnetic data, indicate that the region lay in low paleolatitudes during the ca 25 Ma-long interglacial interval. Thermal demagnetisation of samples from the Angepena Formation at Depot Flat in the western Flinders Ranges and Nepouie Creek and Balcanoona Creek in the northeastern Flinders Ranges revealed a high-temperature component that decayed to the origin at ∼680°C, consistent with hematite being the only magnetic mineral present. Restoring the strata to the paleohorizontal yielded a positive fold test at the 99% confidence level. The concordance of results for widely separated sites and the positive fold test argue for the early acquisition of remanence before folding of the strata du...

Weathering profiles 2–3 m thick mantle a palaeoplain formed on the Lewisian Complex and are overlain unconformably by fluvial conglomerates of the c . 980 Ma Applecross Formation (Torridon Group) in NW Scotland. Geological and palaeomagnetic data indicate that the profiles formed penecontemporaneously with deposition of the Applecross Formation and constitute the oldest known palaeosols in Britain. However, their degree of later alteration and burial depth are contentious. The weathering profiles are characterized by the presence of mixed-layer illite–smectite and smectite, which is anomalous for Precambrian palaeosols, raising doubts regarding a Precambrian age for the clay suite. Estimates of burial depth range from c . 6 km and possibly c . 12 km following Caledonian tectonism. Thin (1–10 mm) veins of saddle (baroque) dolomite are present in weathered amphibolite ≤1 m below the Lewisian–Torridon Group unconformity and also in overlying conglomerate 15 km SSW of Cape Wrath, indicating the flow of heated ( c . 90–160 °C) saline fluids. The anomalous occurrence of mixed-layer illite–smectite and smectite in these Precambrian palaeosols implies ‘retrograde diagenesis’ of diagenetic illite and chlorite likewise induced by hydrothermal fluids. Alteration of the palaeosols is attributed to hydrothermal fluid flow along the Lewisian–Torridon Group unconformity that was related to fluid movement in the Moine Thrust zone during Silurian or Permian regional tectonism. Radiometric dating of the illite may illuminate the timing of alteration of the palaeosols and their burial history.

Determining the effects of compaction-related inclination shallowing of remanence directions is crucial for ascertaining the validity of low palaeolatitudes for Neoproterozoic red beds in South Australia that are central to the debate concerning low-latitude Proterozoic glaciation. The inclination correction (or flattening) factor, f, is defined as tan(ID)/tan(IF), where ID and IF are the inclinations of the measured detrital remanence and the ancient inducing field, respectively. The anisotropy can be estimated using anisotropy of magnetic susceptibility and the anisotropy of high-field isothermal remanence (hf-AIR). The elongation–inclination (E–I) method has also been used to infer inclination shallowing. We add the anisotropy of thermoremanent magnetisation (ATR) to these methods. For the late Cryogenian Elatina Formation arenites, which constitute the bulk of the Elatina data set, the inclination correction using f = 0.738 derived from ATR increases the palaeolatitude of the Elatina Formation from 6.5 ± 2.2° to 8.8 ± 3.2°, which confirms that the Elatina glaciation occurred near the palaeoequator. Inclination corrections for the Ediacaran argillaceous Brachina and Wonoka formations, using f = 0.35–0.38 derived from ATR, are significantly greater than for the more arenaceous Elatina Formation, which increases their palaeolatitudes from ~ 12° to ~ 30°. Carbonates from the basal Ediacaran Nuccaleena Formation yielded f = 0.8 from ATR, which represents only a small palaeolatitude correction from 19° to 23°. The anisotropy results imply that the characteristic remanent magnetisations carried by all these units were acquired early as depositional remanent magnetisations, essentially at the time of deposition. The shift of the palaeopoles from argillaceous units indicating significantly higher palaeolatitudes introduces a distinctive loop into the late Cryogenian–Ediacaran–Cambrian pole path for Australia. This loop shows similarities with the North American pole path for this period, for which true polar wander (TPW) has been inferred. However, until ages of Neoproterozoic strata in South Australia are better constrained uncertainty persists on whether the similarities of the Australian and North American pole paths reflect TPW.

The ephemeral nature of most sedimentation processes and the fragmentary character of the sedimentary record are of first-order importance. Despite a basic uniformity of external controls on sedimentation resulting in markedly similar lithologies, facies, fades associations and depositional elements within the rock record across time, there are a number of secular changes, particularly in rates and intensities of processes that resulted in contrasts between preserved Precambrian and Phanerozoic successions. Secular change encompassed (1) variations in mantle heat, rates of plate drift and of continental crustal growth, the gravitational effects of the Moon, and in rates of weathering, erosion, transport, deposition and diagenesis; (2) a decreasing planetary rotation rate over time; (3) no vegetation in the Precambrian, but prolific microbial mats, with the opposite pertaining to the Phanerozoic; (4) the long-term evolution of the hydrosphere-atmosphere-biosphere system. A relatively abrupt and sharp turning point was reached in the Neoarchaean, with spikes in mantle plume flux and tectonothermal activity and possibly concomitant onset of the supercontinent cycle. Substantial and irreversible change occurred subsequently in the Palaeoproterozoic, whereby the dramatic change from reducing to oxidizing volcanic gases ushered in change to an oxic environment, to be followed at ca. 2.4-2.3 Ga by the "Great Oxidation Event" (GOE); rise in atmospheric oxygen was accompanied by expansion of oxygenic photosynthesis in the cyanobacteria. A possible global tectono-thermal "slowdown" from ca. 2.45-2.2 Ga may have separated a preceding plate regime which interacted with a higher energy mantle from a ca. 2.2-2.0 Ga Phanerozoic-style plate tectonic regime; the "slowdown" period also encompassed the first known global-scale glaciation and overlapped with the GOE. While large palaeodeserts emerged from ca. 2.0-1.8 Ga, possibly associated with the evolution of the supercontinent cycle, widespread euxinia by ca. 1.85 Ga ushered in the "boring billion" year period. A second time of significant and irreversible change, in the Neoproterozoic, saw a second major oxidation event and several low palaeolatitude Cryogenian (740-630 Ma) glaciations. With the veracity of the "Snowball Earth" model for Neoproterozoic glaciation being under dispute, genesis of Pre-Ediacaran low-palaeolatitude glaciation remains enigmatic. Ediacaran (635-542 Ma) glaciation with a wide palaeolatitudinal range contrasts with the circum-polar nature of Phanerozoic glaciation. The observed change from low latitude to circum-polar glaciation parallels advent and diversification of the Metazoa and the Neoproterozoic oxygenation (ca. 580 Ma), and was succeeded by the Ediacaran-Cambrian transition which ushered in biomineralization, with all its implications for the chemical sedimentary record. (C) 2012 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Alluvial-channel and overlying eolian deposits exposed in coastal cliffs in the Port Campbell australite (Australian tektite) strewn field, SW Victoria, were studied stratigraphically and dated by optically stimulated luminescence (OSL) for quartz sand grains to illuminate the occurrence of australites in this area. The channel deposits, termed the Dog Trap Bay Sand, yielded OSL ages from 420 ± 40 to 230 ± 15 ka for four sites, and the two eolian units OSL ages of 203 ± 16 and 93 ± 11 ka. The ages support field evidence that, contrary to the conclusions of a previous study by others, the channel deposits are stratigraphically distinct from and much younger than the Pliocene Hanson Plain Sand, which forms a regionally extensive system of marine strandlines to the north and NE of Port Campbell. The OSL ages show some preference for times of negative temperature anomalies marking the last four glacial periods of the Middle and Late Pleistocene as indicated by ice-core data from Antarctica. Eolian and at leas...

The Flinders Ranges and its surroundings in South Australia comprise an impressive rugged terrain that rises abruptly from piedmont plains to the east and west and merges into the plains of the Cenozoic Lake Eyre Basin to the north. Folded and faulted Neoproterozoic-Cambrian clastic and carbonate sedimentary rocks of the Adelaide Geosyncline (Adelaide Rift Complex) form the predominant geology of the ranges and record varied depositional environments and metamorphic overprints and have had a complex landscape history, resulting in a diverse regolith. This ancient, arid terrain represents some of the best analogue landscapes and settings in Australia to observe features and processes fundamental to the evolution of the Earth. The strata of the Flinders Ranges record the evolution of terrestrial surface environments and the biosphere through the Cryogenian, Ediacaran and Cambrian periods, including evidence for Neoproterozoic glaciations, orbital and rotational dynamics and asteroid impact. The diverse assemblages of stromatolites, ancient and modern hydrothermal systems, and alteration assemblages provide field laboratories for astrobiological and hyperspectral research and training. For these reasons the northern Flinders Ranges near Arkaroola have been selected as a site for multi-disciplinary Mars analogue research and space education.

The Mesoproterozoic Pandurra Formation and Blue Range Beds of the Gawler Craton, South Australia, are undeformed, low-dipping (typically 10–15°) arenites of fluvial origin displaying pale to moderate red colours with light grey mottles and streaks and local Liesegang banding. Eighty-nine core samples and seven block samples were collected from 18 sites in the Pandurra Formation at Whyalla and 70 core samples from 16 sites in the Blue Range Beds at Talia. Specimens from all samples were stepwise thermally demagnetised, revealing hematite as the dominant magnetic carrier with a Neel temperature of 680°C. The mean direction for the Pandurra Formation after tilt-correction (N = 90 specimens) is declination = 248.2°, inclination = 46.7° (α95 = 4.4°), indicating a paleolatitude of 27.9 +3.9/–3.4° and a pole position at latitude 33.6°S, longitude 64.5°E (A 95 = 4.9°). The mean direction for the Blue Range Beds after tilt-correction (N = 61) is declination = 233.9°, inclination = 50.2° (α95 = 4.0°), with a paleol...

Sedimentary features characteristic of ice-rafting are present in the Bunyeroo Formation (Wilpena Group) of the Adelaide Geosyncline and in the coeval Dey Dey Mudstone (Ungoolya Group) of the eastern Officer Basin (Figs 66.1 & 66.2), providing evidence of a mid-Ediacaran glacial climate in South Australia. The Acraman asteroid impact, a negative shift in marine δ 13 C, and a major acritarch turnover coincided with this frigid epoch.

Deposits of the late Cryogenian Elatina glaciation constitute the Yerelina Subgroup in the Adelaide Geosyncline region, South Australia. They have a maximum thickness of c . 1500 m, cover 200 000 km 2 , and include the following facies: basal boulder diamictite with penetrative glaciotectonites affecting preglacial beds; widespread massive and stratified diamictites containing faceted and striated clasts, some derived from nearby emergent diapiric islands and others of extrabasinal provenance; laminated siltstone and mudstone with dropstones; tidalites and widespread glaciofluvial, deltaic to marine-shelf sandstones; a regolith of frost-shattered quartzite breccia up to 20 m thick that contains primary sand wedges 3+ m deep and other large-scale periglacial forms; and an aeolian sand sheet covering 25 000 km 2 and containing primary sand wedges near its base. These deposits mark a spectrum of settings ranging from permafrost regolith and periglacial aeolian on the cratonic platform (Stuart Shelf) in the present west, through glaciofluvial, marginal-marine and inner marine-shelf in the central parts of the Adelaide Geosyncline, to outer marine-shelf in sub-basins in the present SE and north. The Elatina glaciation has not been dated directly, and only maximum and minimum age limits of c . 640 and 580 Ma, respectively, are indicated. Palaeomagnetic data for red beds from the Elatina Formation (Fm.) and associated strata indicate deposition of the Yerelina Subgroup within 10° of the palaeoequator. The Yerelina Subgroup is unconformably to disconformably overlain by the dolomitic Nuccaleena Fm., which in most places is the lowest unit of the Wilpena Group and marks Early Ediacaran marine transgression. Supplementary material: Photographs are available at http://www.geolsoc.org.uk/SUP18481.

The record of two Neoproterozoic glaciations in South Australia has been known for about a century. The earlier glaciation, of Sturtian age, is represented by the Yudnamutana Subgroup and is characterized by widespread diamictites with both intrabasinal and extrabasinal clasts, some locally faceted and striated. Associated facies include shallow-water sandstone, bedded and laminated siltstone with lonestones and dropstones, and sedimentary ironstones (mainly ferruginous siltstone and diamictite). Proximal settings adjacent to the Curnamona Province display massive basement-derived conglomerate and gigantic basement megaclasts (up to hundreds of metres across). Sturtian glaciogenic sediments of the Yudnamutana Subgroup unconformably overlie a variety of older rock units, including crystalline basement near basin margins and uppermost Burra Group sediments in the depocentre, and were deposited both in shallow marine shelf environments and in tectonically active rift basins encircling the Curnamona Province, with corresponding increases in total thickness from 100–300 m to more than 5 km. Recent U–Pb zircon SHRIMP dating of a thin volcaniclastic layer indicates that the waning stages of the Sturtian glaciation occurred at c. 660 Ma. Unlike the deposits of the younger Elatina glaciation, the Yudnamutana Subgroup has so far not yielded reliable palaeomagnetic data.

Isolated quartzose pebbles, clusters of quartz granules, orthogonal aggregates of poorly sorted quartzose coarse sand, and ovoid pellets (≤2 mm long) of quartz silt occur in hemipelagic marine mudstone of the mid-Ediacaran Bunyeroo Formation exposed in the Adelaide Geosyncline (Adelaide Rift Complex), and ovoid pellets of quartz silt in cores of the correlative marine Dey Dey Mudstone from deep drillholes in the Officer Basin, South Australia. This detritus is interpreted respectively as dropstones, dumps, and frozen aggregates dispersed by sea ice possibly of seasonal origin, and till pellets transported by glacial ice. The ice-rafted material in the Bunyeroo Formation only has been found 500 km northwest of ...

SUMMARY We report new palaeomagnetic data for red beds from the Ediacaran Brachina and Wonoka formations in the Adelaide Geosyncline, South Australia, and discuss their place with previously determined poles in the Ediacaran apparent polar wander path for Australia. Both formations behave similarly on thermal demagnetization, displaying high-temperature components that decay to the origin at 680 ◦ C, consistent with haematite being the only magnetic mineral present. Restoring the strata to the palaeohorizontal yielded positive fold tests for both units at 99 per cent confidence, indicating that acquisition of magnetization occurred before the early Palaeozoic Delamerian Orogeny. For the Brachina Formation (N = 91 specimens) the mean direction after unfolding is declination D = 178.2 ◦ , inclination I = –22.6 ◦ (α95 = 4.4 ◦ ), indicating a palaeolatitude λ = 11.8 ± 2.5 ◦ and a pole position at latitude λp = 46.0 ◦ S, longitude ϕp = 315.4 ◦ E, with confidence semi-axes dp = 2.4 ◦ and dm = 4.6 ◦ . The mean direction for the Wonoka Formation after unfolding (N = 70) is D = 255.9 ◦ , I = –23.7 ◦ (α95 = 6.4 ◦ ), indicating λ = 12.3 +3.8/–3.4 ◦ and a pole position at latitude λp = 5.2 ◦ S, longitude ϕp = 30.5 ◦ E( dp = 3.6 ◦ and dm = 6.8 ◦ ). The mean directions for these units and other Ediacaran units in the Adelaide Geosyncline are significantly different from each other, which excludes blanket remagnetization of the units before Delamerian folding and therefore gives strong preference to their magnetization dating from close to the time of deposition. The late Cryogenian–Ediacaran–Cambrian apparent polar wander path for South Australia spans 150 Myr from ∼635 to 490 Ma and places Australia in low palaeolatitudes throughout the interval studied. The poles differ significantly from each other, suggesting Australia underwent continual drift during that time. Whereas the directional difference between the late Cryogenian Elatina Formation and early Ediacaran Nuccaleena Formation is mainly in inclination, for most other contiguous stratigraphic units the differences are mainly in declination with minor inclination differences, indicating Australia was rotating about a nearby Euler pole in low palaeolatitudes. The large and perhaps rapid polar shifts at 615–590 and 575–565 Ma in the Laurentian apparent polar wander path are not evident in the Ediacaran apparent polar wander path for Australia. Because true polar wander should be recorded globally, in the absence of evidence for any major stratigraphic break in the South Australian succession we conclude that large true polar wander did not occur during the Ediacaran.

The Ediacaran Global Stratotype Section and Point (GSSP) is defined near the base of the Nuccaleena Formation, the “cap carbonate” overlying the terminal Cryogenian glaciogenic Elatina Formation at a basin-wide sequence boundary in the Adelaide Geosyncline, South Australia. Previous palaeomagnetic data for 205 specimens from the Elatina Formation yielded a structurally corrected mean declination D = 208.3° and inclination I = −12.9° ( α 95 = 4.2°), palaeolatitude λ = 6.5 ± 2.2° and pole position at latitude λ p = 47.3°S, longitude φ p = 359.3°E (dp = 2.1° and dm = 4.2°). New palaeomagnetic data for 141 specimens from the Nuccaleena Formation yield a structurally corrected mean direction of D = 208.3°, I = −34.9° ( α 95 = 3.4°), λ = 19.2 + 2.3/−2.2° and pole position at λ p = 32.3°S, φ p = 350.8°E (dp = 2.2° and dm = 3.9°). There is a substantial difference in inclination between the Elatina and Nuccaleena formations, despite their juxtaposition. Positive fold tests for both formations seem to rule out remagnetisation of one or both formations. Fold tests on tepee-like structures in the Nuccaleena Formation accord with the magnetisation having been acquired at or near the time the structures formed during early diagenesis. Magnetisation therefore variably lags deposition, causing the three identified magnetostratigraphic horizons to appear highly bedding-transgressive; whereas local correlations may seem satisfactory, regional correlations are not. Nevertheless, the number and duration of polarity chrons at various localities appear valid, implying that the Nuccaleena Formation accumulated over an interval of >10 5 years. The question of compaction-related inclination shallowing was addressed by examining the anisotropy of remanence using a superconducting 12 T magnet. The effective flattening factors f determined were: Nuccaleena dolostones, N = 4, f = 0.98 ± 0.02; Elatina tidal rhythmites, N = 6, f = 0.97 ± 0.01; Elatina arenites, N = 9, f = 0.92 ± 0.02. The mean Elatina inclination is corrected to −14.0° (palaeolatitude of 7.1°) and the mean Nuccaleena inclination to −35.4° (palaeolatitude of 19.6°). Inclination shallowing also was investigated using the Elongation–Inclination method. The distributions of directions for the Elatina were somewhat skewed with respect to bedding, possibly invalidating use of this method. Nevertheless, for the Elatina the method yields an inclination of −19° (palaeolatitude of 10°). For the Nuccaleena, the corrected inclination is −41.9° (palaeolatitude of 24°). These corrections do not materially alter the near-equatorial palaeolatitude for the Elatina Formation, which is supported by data for other Neoproterozoic strata in southern Australia. However, the substantial increase in palaeolatitude between the late Cryogenian and the early Ediacaran is maintained. The sequence boundary below the Nuccaleena Formation is a disconformity to low-angle unconformity that in places cuts deeply into the ∼1500 m thick, late Cryogenian glaciogenic succession, and may represent a significant time gap marked by rapid polar wander. Such a hiatus may be an important factor in the juxtaposition of glacial deposits and cap carbonates.

The 1.8 Ga King Leopold glaciation in northwestern Australia is recorded in the Kimberley Basin by subglacial erosional forms cut in an unconformity surface at the top of the Speewah Group and buried by glaciofluvial deposits at the base of the King Leopold Sandstone, the lowest formation of the Kimberley Group. The glaciofluvial deposits are conformably overlain by texturally mature, locally glauconitic quartzarenite of shallow-marine origin, implying that glaciation occurred near sea level. Palaeomagnetic data for five sites (29 specimens) in the hematite-bearing Elgee Siltstone of the upper Kimberley Group in the northeastern Kimberley Basin gave a dip-corrected mean direction of declination D = 95.4°, inclination I = 13.8° (α95 = 9.7°), indicating a palaeolatitude λ = 7.0 +5.3/−5.0°. Results for red beds from five sites (28 specimens) in the conformably overlying Pentecost Sandstone gave a dip-corrected mean direction of D = 94.1°, I = 13.0° (α95 = 11.7°), λ = 6.6 +6.4/−5.9°. Combining our data for the Elgee Siltstone and Pentecost Sandstone with results for the Elgee Siltstone in the southeastern Kimberley Basin [Li, Z.X., 2000. Palaeomagnetic evidence for unification of the North and West Australian cratons by ca. 1.7 Ga: new results from the Kimberley Basin of northwestern Australia. Geophysical Journal International 142, 173–180.] yielded a dip-corrected mean direction for 17 sites of D = 93.5°, I = 15.1° (α95 = 4.4°), palaeolatitude λ = 7.7 ± 2.3°, and an overall pole position at latitude λp = 5.4°S, longitude φp = 211.8°E, with confidence semi-axes dp = 2.3° and dm = 4.5°. A positive fold test at 99% confidence was obtained for the combined data for the 17 sites. The basinwide concordance of results for the Elgee Siltstone and the positive fold test argue for an early magnetisation acquired prior to late Palaeoproterozoic initial folding of the Kimberley Group and close to the time of deposition. Our results imply a low palaeolatitude for the Kimberley Group and the King Leopold glaciation. Palaeomagnetic data for the 1.822 Ga Plum Tree Creek Volcanics in the Pine Creek Orogen to the east of the Kimberley Basin are consistent with northwestern Australia being in low palaeolatitudes during the late Palaeoproterozoic. Hence the enigma of glaciation near sea level in low palaeolatitudes, which marks the Neoproterozoic and early Palaeoproterozoic, applies also to the late Palaeoproterozoic. Red beds from the Lansdowne Arkose of the Speewah Group also were studied, but only directions ascribable to Tertiary regolith weathering processes were found. Similar findings for the late Palaeoproterozoic McArthur Basin in northern Australia suggest some units in that basin also record Tertiary regolith processes.

The late Cryogenian Elatina glaciation in South Australia, of Marinoan age, is named after the Elatina Formation of the glaciogenic Yerelina Subgroup, which covers ∼200,000 km2 in the Adelaide Geosyncline and on the cratonic Stuart Shelf and is up to ∼1500 m thick. The Elatina glaciation is marked by numerous facies that are like those of Phanerozoic glaciations: • Basal diamictite displaying glacitectonites with penetrative deformation of preglacial beds, indicating grounded ice or scouring by icebergs. • Glaciomarine diamictites containing numerous faceted and striated clasts up to several metres across of intrabasinal and extrabasinal origin. • Laminated siltstone and mudstone containing scattered, ice-rafted dropstones in outer marine-shelf environments. • Sandstones deposited in fluvial, deltaic and inner marine-shelf settings. • Tidalites deposited in estuaries and on tidal deltas during interstadial rise of sea level, with cyclic tidal rhythmites recording the annual oscillation of sea level and displaying wave-generated ripple marks, which together indicate long-lived and extensive open seas. • Siltstone containing acicular crystal pseudomorphs implying the formation of evaporite minerals in littoral deposits. • Permafrost regolith of frost-shattered quartzite breccia ≤20 m deep, displaying large-scale periglacial structures including primary sand wedges 3 m deep that indicate a frigid, strongly seasonal climate near sea level. • Periglacial–aeolian sandstone covering 25,000 km2 and containing primary sand wedges near its base. These deposits record a spectrum of settings ranging from permafrost regolith and periglacial sand sheet on the Stuart Shelf in the west, through fluvial, deltaic and inner marine-shelf in the western and central parts of the Adelaide Geosyncline, to outer marine-shelf in the north and southeast. The widespread and persistent rainout of fine-grained sediment and ice-rafted debris indicates that the sea was not frozen over during the Elatina glaciation. No direct age determination is available for the Elatina glaciation, and only maximum and minimum age limits of ∼640 and ∼580 Ma, respectively, can at present be applied. High-quality palaeomagnetic data for red beds from the Elatina Formation, supported by positive fold tests on soft-sediment slump folds that demonstrate the early acquisition of magnetic remanence, indicate deposition within 10° of the palaeoequator. The Yerelina Subgroup in the Adelaide Geosyncline and on the Stuart Shelf is disconformably to unconformably overlain by the Nuccaleena Formation “cap carbonate” that marks the early Ediacaran post-glacial marine transgression. The presence in near-equatorial palaeolatitudes of glaciomarine deposition, grounded ice and permafrost near sea level, a strongly seasonal periglacial climate, and widespread open seas implies a paradoxical palaeoclimate and palaeogeographic setting for the Elatina glaciation. The strong evidence for a non-actualistic late Cryogenian glacial climate in South Australia has been a stimulus to worldwide multidisciplinary research on Cryogenian glaciogenic successions.

Sedimentological observations and palaeomagnetic data for Cryogenian glacial deposits present the climatic paradox of grounded glaciers and in situ cold climate near sea-level, glaciomarine deposition, and accompanying large (up to 40 °C) seasonal changes of temperature, all in low to near-equatorial ( 54°) obliquity of the ecliptic, which would render the equator cooler than the poles, on average, and amplify global seasonality. A high obliquity per se would not have been a primary trigger for glaciation, but would have strongly influenced the latitudinal distribution of glaciers. The principle of low-latitude glaciation on a terrestrial planet with high obliquity is validated by theoretical studies and observations of Mars. A high obliquity for the early Earth is a likely outcome of a single giant impact at 4.5 Ga, the widely favoured mechanism for lunar origin. This implies that a high obliquity could have prevailed during most of the Precambrian, controlling the low palaeolatitude of glaciations in the early and late Palaeoproterozoic and Cryogenian. It is postulated that the obliquity changed to The High Obliquity, Low-latitude Ice, STrong seasonality (HOLIST) hypothesis for pre-Ediacaran glaciation emerges favourably from numerous glacial and non-glacial tests. The hypothesis is in accord with such established or implied features of Cryogenian glaciogenic successions as extensive and long-lived open seas, an active hydrological cycle, aridity and palaeowesterly (reversed zonal) winds in low palaeolatitudes, and the apparent diachronism or non-correlation of some low-palaeolatitude glaciations. A pre-Ediacaran high obliquity also offers a viable solution of the faint young Sun paradox of a warm Archaean Earth. Furthermore, reduction of obliquity during the Ediacaran–early Palaeozoic would have yielded a more habitable globe with much reduced seasonal stresses and may have been an important factor influencing the unique evolutionary events of the Ediacaran and Cambrian. The palaeolatitudinal distribution of evaporites cannot discriminate unambiguously between high- and low-obliquity states for the pre-Ediacaran Earth. Intervals of true polar wander such as postulated by others for the Ediacaran and Early Cambrian imply major mass-redistributions within the Earth at those times, which may provide a potential mechanism for reducing the obliquity during the Ediacaran–early Palaeozoic.

An apparent sine wave pattern of columns in a single specimen of the stromatolite Anabaria juvensis (subsequently identified as Kotuikania) from a Neoproterozoic dolomite unit, originally assigned to the ∼850 Ma Bitter Springs Formation, in the Amadeus Basin, central Australia, was interpreted previously as recording heliotropic growth, that is, the non-vertical growth of columns throughout the year controlled by averaged incident solar radiation [Vanyo, J.P., Awramik, S.M., 1985. Stromatolites and Earth– Sun–Moon dynamics. Precambrian Research 29, 121–142]. The model of heliotropic growth was used to estimate obliquity of the ecliptic (Earth's axial tilt) and days/year at 850 Ma. Subsequent work, however, casts strong doubt on the heliotropic interpretation. Further field observations and the study of 11 additional specimens of Anabaria=Kotuikania juvensis from the original locality confirm that the columns typically display strong branching, which produces a common divergence and convergence of columns that is incompatible with heliotropic growth. The rare, apparent sinuosity of columns is seen as the fortuitous product of column irregularity and column branching. Moreover, stratigraphic studies indicate that the host dolomite unit does not belong to the Bitter Springs Formation but caps the younger Cryogenian glaciogenic succession in the Amadeus Basin and hence is ∼600 Ma. The previous estimate of ∼435 (range 409–485) days/year based on extrapolated counts of laminae in the original specimen of A.=K. juvensis conflicts with the figure of 400±7 days/year indicated by high-quality palaeotidal data obtained from the late Cryogenian (∼640–600 Ma) Elatina–Reynella tidal rhythmites in South Australia. We conclude that inferences concerning Neoproterozoic obliquity and palaeorotation cannot be drawn from the non-vertical growth patterns of the columnar stromatolite A.=K. juvensis. © 2007 Elsevier B.V. All rights reserved.

SUMMARY The pole position for the late Mesoproterozoic Alcurra (formerly Kulgera) Dyke Swarm (ADS), Musgrave Block, central Australia, has been revised by adding new data from two more dykes. A palaeomagnetic fold test is positive at the 99 percent confidence level and the pole position is latitude = 2.8° S, longitude = 80.4°E (dp= 7.2°, dm= 10.7°). New 40Ar/39Ar determinations on single biotite grains from country-rock gneiss 20 cm from the contact with an Alcurra dyke yield ages from 1068 ± 2 Ma to 1085 ± 2 Ma (2σ). In addition, 40Ar/39Ar determinations on two samples of aggregates of very fine-grained biotite from the mesostasis of a Stuart Dyke (SD), Arunta Inlier, Northern Territory, yield ages of 1059 ± 2 and 1066 ± 3 Ma (2σ). These new ages are in agreement with those of the ∼1070 Ma Warakurna large igneous province, west-central Australia, indicating that both the ADS and SD belong to that suite. Palaeomagnetic poles determined by others for the ADS and SD are indistinguishable from each other but cannot be presently combined as a single pole because the published information on the SD is incomplete. An analysis of the palaeogeography implied by the dispersed palaeomagnetic poles from members of the extended Warakurna suite shows that the present relationships between the major Precambrian cratons (West, North and South Australian), which constitute Australia west of the Tasman Line, are inconsistent with the inferred relationship at ∼1070 Ma. Nor is it apparent that internal deformations within the separate cratons are the cause of the dispersion. Our findings imply that these major Australian Cratons must have finally assembled sometime after ∼1070 Ma.

Multidisciplinary research during the past 25 years has established that the Acraman impact structure in the 1.59 Ga Gawler Range Volcanics on the Gawler Craton, and an ejecta horizon found 240 – 540 km from Acraman in the ⩽ 580 Ma Bunyeroo Formation in the Adelaide Fold Belt and Dey Dey Mudstone in the Officer Basin, record a Late Neoproterozoic (Ediacaran) event of major environmental importance. Research since 1995 has verified Acraman as a complex impact structure that has undergone as much as 3 – 5 km of denudation and which originally had a transient cavity up to 40 km in diameter and a final structural rim possibly 85 – 90 km in diameter. The estimated impact energy of 5.2 × 106 Mt (TNT) for Acraman exceeds the threshold of 106 Mt nominally set for global catastrophe, and the impact probably caused a severe perturbation of the Ediacaran environment. The occurrence of the impact at a low palaeolatitude (12.5 + 7.1/ − 6.1°) may have magnified the environmental effects by perturbing the atmosphere in ...

The study of tidal rhythmites, involving sedimentology, time-series analysis and astronomy, can contribute to understanding the history of the Earth's rotation and the Moon's orbit. It is regrettable, therefore, that the paper by Mazumder and Arima (2005) [Mazumder R., Arima M., 2005. Tidal rhythmites and their implications. Earth-Sci. Rev. 69, 79–95.] on tidal rhythmites and their implications contains errors of methodology and unsubstantiated speculation that could confuse and mislead. Moreover, contrary to the introductory statement of Mazumder and Arima (2005, p. 79) [Mazumder, R., Arima M., 2005. Tidal rhythmites and their implications. Earth-Sci. Rev. 69, 79–95.] that the analysis of ancient tidal rhythmites “is not straightforward”, the analysis need not be complicated. Problems will arise, however, if the rhythmite raw data are of poor quality and basic astronomical laws are misapplied. Such shortcomings are to be found in the paper under discussion.

A late Palaeoproterozoic unconformity surface developed on low-dipping sandstone in the Kimberley region, northwestern Australia, exhibits numerous linear, parallel grooves 10–50 mm deep, 40–80 mm wide and tens of metres long, and other erosional forms including sichelwannen. These features are interpreted as Nye channels and sculpted forms eroded by subglacial meltwaters. Sandstone-filled cracks exposed at the unconformity are viewed as periglacial frost fissures. An overlying conglomerate facies 1–15 m thick at the base of the c . 1800 Ma King Leopold Sandstone, Kimberley Basin succession, contains poorly sorted, pebble to boulder conglomerate and is interpreted as glaciofluvial in origin. The orientation of the Nye channels and sculpted forms and the palaeocurrent direction for the glaciofluvial deposits indicate westward ice flow. The conformably following, locally glauconitic quartzarenite of the King Leopold Sandstone probably accumulated in an epeiric sea, implying that glaciation reached close to sea level. Transgression in northwestern and central Australia at c . 1800 Ma may have been partly glacio-eustatic. Glaciation was initiated to the east of the Kimberley Basin, evidently in the Halls Creek Orogen, during a major phase of continental collision in Australia and worldwide supercontinental assembly. Recognition of the King Leopold glaciation, which occurred in low palaeolatitudes ( c . 2200 and 800 Ma.

Oriented cores of unweathered Frere Formation (1.9–1.8 Ga), including shaly and peloidal iron-formation, were obtained from two holes drilled to 116 m depth on opposite limbs of an anticline in the southern Earaheedy Basin at the northeastern margin of the Yilgarn Craton. Anisotropy of magnetic susceptibility measurements indicated that the Frere Formation in this area was unaffected by regional metamorphism. The predominant magnetic mineral in the iron-formation is hematite but a small amount of magnetite also is present in some samples. Stepwise thermal demagnetisation was conducted for 263 specimens. Many specimens acquired spurious components of magnetisation after treatment to 300–500 °C, ascribable to the oxidation of siderite to magnetite on heating. However, other specimens displayed a stable, high-temperature (680 °C), dual-polarity component A carried by hematite that gave a bedding dip-corrected direction of D=314.3°, I=−24.8° (K=38.5, α95=2.6°, n=78). A fold test was positive at >99% level of confidence, indicating acquisition of remanence prior to Stanley folding in the Earaheedy Basin that occurred at ∼1.78 Ga near the end of Capricorn orogenesis. The presence of polarity reversals in the stratigraphic section from one drill hole and within some specimens argues for the identification of a dipole field axis and the sufficient averaging of secular variation to define a palaeopole for the Frere Formation, located at 45.2°S, 220.0°E (dp=1.3°, dm=2.4°). Component A is ascribed to a chemical remanent magnetisation (CRM) acquired soon after deposition, and indicates a palaeolatitude of 13.0±1.5° for the Frere Formation. The Frere pole plots adjacent to, but is still significantly different from, late to post-Capricorn Orogeny overprint poles from the Hamersley Province of the southern Pilbara. However, vertical-axis relative anticlockwise rotation of 10–15° for the Frere pole brings it close to these Pilbara overprint poles. The data imply that the Earaheedy Basin and possibly the Yilgarn Craton underwent clockwise rotation of 10–15° relative to the Pilbara Craton during Stanley folding. This finding accords with evidence for tectonic settings marked by sinistral strike-slip deformation adjacent to the Yilgarn–Pilbara cratonic boundary during deposition and subsequent folding in the Earaheedy Basin. The data also imply that the West Australian and North Australian cratons were in close proximity by ∼1.8 Ga.

Thirty-nine oriented block samples of iron-formation were collected at 13 sites, including opposite limbs of major folds, from the 1.88-Ga Sokoman Formation (Knob Lake Group) in the Schefferville–Knob Lake area of the central New Quebec Orogen, northern Quebec. The samples assayed up to 80.24% Fe2O3T (54.08% Fe), implying Fe-enrichment of the iron-formation up to ore grade. Anisotropy of magnetic susceptibility measurements on 245 standard specimens indicate a well preserved bedding-parallel fabric in the iron-formation, suggesting minimal alteration of the magnetic mineralogy since deposition and/or a mimetic secondary magnetic mineralogy. The iron-formation has not been internally deformed since the magnetic mineralogy was established. Analyses by variable-field translation balance and X-ray diffraction showed that the predominant magnetic mineral is hematite but a small amount of magnetite also is present in most samples. Following low-temperature pre-treatment as appropriate, stepwise thermal and alternating-field demagnetization of 218 specimens revealed a low-temperature, post-folding component (maximum Tub≈400 °C, D=27.1°, I=20.1°, α95=10.9°, from seven sites; pole position of 40.6°S, 257.0°E), and components carried by magnetite (maximum Tub≈580 °C, D=35.8°, I=3.9°, α95=9.1°, from 10 sites; pole position of 29.6°S, 250.9°E) and hematite (maximum Tub≈680 °C, D=40.0°, I=1.6°, α95=18.6°, from seven sites; pole position of 26.8°S, 247.0°E). The components carried by magnetite and hematite are pre-, syn- and post-folding depending on the sampling site, indicating that the magnetization was acquired continuously with deformation in the New Quebec Orogen at 1.84–1.83 Ga. No evidence was found for acquisition of magnetization during the Mesozoic, when many of the iron oxide orebodies in the Schefferville–Knob Lake area are thought to have formed. Our findings imply that an episode of Fe-enrichment of iron-formation in the Sokoman Formation involved the circulation of hydrothermal fluids related to late Paleoproterozoic orogenesis. Such orogenic circulation of fluids may have contributed to the development of hematitic orebodies in the central New Quebec Orogen.

Acraman, located in the 1.59 Ga Gawler Range Volcanics on the Gawler Craton, South Australia, is a complex impact structure that is now eroded ≥2.5 km below the original crater floor. The geology, geomorphology, apatite fission-track geochronology, and geophysical signature of Acraman suggest that the original crater comprised highly disturbed rocks of a central uplift, a transient cavity up to c . 40 km in diameter, and a possible final structural rim at 85–90 km diameter. Radial unfolded distance from the centre of Acraman, versus decompacted thickness for the Acraman ejecta horizon identified in late Vendian ( c . 580 Ma) mudstone in the Adelaide fold belt, Torrens Hinge Zone and Officer Basin up to 540 km from the impact site, accords with a transient cavity diameter of c . 40 km. The estimated impact energy for Acraman exceeds the threshold of 10 6 Mt set by earlier workers for global catastrophe. The impact occurred at a low palaeolatitude ( c . 12.5°) and probably perturbed the atmosphere in both the northern and southern hemispheres. The Acraman impact probably caused a severe perturbation of the late Vendian environment, a finding consistent with independent data from the Vendian palynology of Australia that the Acraman impact induced a biotic crisis.

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.

In South Australia, canyons 200–250 km long are incised to depths of c . 1.5 km in late Neoproterozoic (after c . 590 Ma) marine deposits of the Adelaide fold belt and canyons 90 km long and 700 m deep occur in correlative marine strata of the Officer Basin 1000 km to the NW. In the Adelaide fold belt, the isotopic signature of limestone veneering canyon walls, canyon sinuosity and sedimentary structures in canyon fill suggest that the canyons were cut subaerially and filled by shallow-water marine deposits during coastal onlap. Eustacy cannot account for the kilometre-scale change in sea level required for subaerial canyon erosion and chemostratigraphy and the lack of evaporites at that stratigraphic level in southern Australia argue against a Messinian-style drawdown. In each region, uplift and crustal extension preceding or coeval with canyon incision are indicated by a regional unconformity, turbidite or mass-flow deposition, and extensional faults. These features and canyon incision may be explained by regional uplift above a rising mantle plume over a distance of >1000 km in southern Australia. Flood basalt volcanism in the Officer Basin tentatively dated at 563±40 Ma may have followed this uplift. Mantle plume uplift is expressed in the sedimentary record by emergent trends in facies, regional thinning, regional unconformities, turbidites, gravity slides, normal faults and incised canyons and palaeovalleys.

Over the past decade the analysis of sedimentary cyclic rhythmites of tidal origin, i.e., stacked thin beds or laminae usually of sandstone, siltstone, and mudstone that display periodic variations in thickness reflecting a strong tidal influence on sedimentation, has provided information on Earth's paleorotation and the evolving lunar orbit for Precambrian time (before 540 Ma). Depositional environments of tidal rhythmites range from estuarine to tidal delta, with a wave-protected, distal ebb tidal delta setting being particularly favorable for the deposition and preservation of long, detailed rhythmite records. The potential sediment load of nearshore tidal currents and the effectiveness of the tide as an agent of sediment entrainment and deposition are related directly to tidal range (or maximum tidal height) and consequent current speed. Hence the thickness of successive laminae deposited by tidal currents can be a proxy tidal record, with paleotidal and paleorotational values being determined by analysis of measured records of lamina and cycle thickness. The validity of the findings can be investigated by testing the primary, observed values for internal self-consistency through application of the laws of celestial mechanics. Paleotidal and paleorotational values provided by late Neoproterozoic (∼620 Ma) tidal rhythmites in South Australia are validated by these tests and indicate 13.1±0.1 synodic (lunar) months/yr, 400±7 solar days/yr, a length of day of 21.9±0.4 h, and a relative Earth-Moon distance a/a0 of 0.965±0.005. The mean rate of lunar recession since that time is 2.17±0.31 cm/yr, which is little more than half the present rate of lunar recession of 3.82±0.07 cm/yr obtained by lunar laser ranging. The late Neoproterozoic data militate against significant overall change in Earth's moment of inertia and radius at least since 620 Ma. Cyclicity displayed by Paleoproterozoic (2450 Ma) banded iron formation in Western Australia may record tidal influences on the discharge and/or dispersal of submarine hydrothermal plumes and suggests 14.5±0.5 synodic months/yr and a/a0 = 0.906±0.029. The combined rhythmite data give a mean rate of lunar recession of 1.24±0.71 cm/yr during most of the Proterozoic (2450–620 Ma), suggesting that a close approach of the Moon did not occur during earlier time. Concentrated study of Precambrian tidal rhythmites promises to illuminate the evolving dynamics of the early Earth-Moon system and may permit the lunar orbit to be traced back to near the time of the Moon's origin.

The paleomagnetism of a saprolitic paleosol developed on Archean granite and of an overlying hematitic breccia in the basal Lorrain Formation of the Cobalt Group (Huronian Supergroup, ∼2.4–2.3 Ga) near Ville-Marie, Quebec, has been investigated to further constrain the paleolatitude of the Lorrain Formation and the subjacent glaciogenic Gowganda Formation. Only the breccia, whose hematite may be a product of weathering prior to or shortly after deposition, yielded useable results with stepwise thermal demagnetization. A stable component A (maximum unblocking temperature, T ub , of ∼675°C) carried by hematite is directed shallowly to the east-northeast ( D =59.5°, I =2.4°, α 95 =6.7°, n =47, dip-corrected), and a less stable component B (maximum T ub of ∼580°C) carried by magnetite is directed steeply down to the northeast ( D =52.1°, I =70.3°, α 95 =2.8°, n =75, dip-corrected). Component A is ascribed to a chemical remanent magnetization (CRM) acquired when the hematitic breccia was deposited or soon thereafter. Component B is interpreted as a thermochemical overprint related to the Penokean Orogeny at 1.9–1.8 Ga. Dip-corrected specimen mean directions give the pole positions at latitude = 57.1°N, longitude = 338.3°E (dp = 4.1°, dm = 4.8°) for component B, and latitude = 21.1°S, longitude = 213.1°E (dp = 3.3°, dm = 6.7°) for component A. The more easterly directions for components A and B relative to comparable early and overprint components previously determined for the Lorrain and Gowganda formations at Elliot Lake and Desbarats 260–360 km southwest of Ville-Marie imply relative rotation of ∼30° or more about a vertical axis within the Southern Province since the Penokean Orogeny. The results suggest that the hematitic breccia and the Ville-Marie paleosol formed at a paleolatitude of 1.2°±3.4°, in accord with our earlier inference of equatorial paleolatitudes for the Lorrain and Gowganda formations and Huronian glaciation. Paleomagnetic data from several continents suggest that ferruginous weathering horizons formed over a wide range of paleolatitudes in the Proterozoic.

We studied the off-response of the rat ERG evoked with long duration, mesopic stimuli during light and dark adaptation, and after intravitreal injection of aspartate and (±)-cis-piperidine-2,3-dicarboxilic acid (PDA). At stimulus offset, the dark-adapted ERG always showed a rapid negative deflection followed by a positive deflection after which the potential returned to baseline. When the stimulus was turned off in the presence of a background of scotopic intensity, the positive deflection consisted of two components. One component was relatively small, fast, and insensitive to rod light adaptation. It resembled the d-wave of the rod ERG. The other component was slow and its amplitude grew with rod light adaptation. In the presence of aspartate, the fast-positive component was absent from the ERG while the remaining positive-going decay of the receptor potential had a time course similar to that of the slow-positive component in the untreated eye. Scotopically matched red and blue stimuli of mesopic intensity elicited equal ERG responses from the dark-adapted eye, including the two positive components in the off-response. These stimuli were also used to assess changes in the ERG off-response during recovery from a strong bleach. Even though the cone contribution to the rat ERG is very small, the presence of a small positive-going component in the off-response following an intense bleach suggested that this response originated from the cone pathway. PDA which suppresses the light response of hyperpolarizing bipolar cells and horizontal cells selectively eliminated the fast-positive component from the ERG. The findings of this study are inconsistent with the idea that the d-wave reflects the decay of the rod receptor potential. They support the possibility that signals from rods cross rod–cone gap junctions at mesopic light intensities, and drive second-order neurons in the cone pathway.

The late Neoproterozoic (ca 600 Ma) Whyalla Sandstone covers 25 000 km2 in outcrop and subcrop on the Stuart Shelf, South Australia, and is coeval with the Marinoan glaciogenic succession in the adjacent Adelaide Fold Belt. The flat‐lying formation is up to 165m thick and comprises mainly reddish brown, medium‐ to very coarse‐grained, well‐rounded, commonly bimodal quartzose sandstone that shows regional south‐southeastward fining. Low‐angle (≤15°) strata form the principal stratification type. Large‐scale cross‐bedded sets up to 7 m thick occur mainly in the central area; cross‐strata usually have dips of ≤20–23° and rarely up to 30°, and display grainfall and grainflow deposits, inversely graded subcritically climbing translatent strata, and pin stripe lamination’. Periglacial cryogenic structures in the basal 5 m of the formation include two generations of primary sand wedges, drop involutions, periglacial injections, frost‐heaved blocks, water‐escape structures, and thermokarst microtopography. Small‐...

To further our understanding of the paleolatitudes of Precambrian glaciations, a paleomagnetic study has been conducted on the glaciomarine Coleman Member of the Gowganda Formation and the conformably overlying deltaic Firstbrook Member and Lorrain Formation (Huronian Supergroup, ∼ 2.4-2.3 Ga) in Ontario, Canada. Many of the rocks, notably the gray and grayish red argillic facies, display unstable magnetization or overprints carried by magnetite and/or hematite that give negative fold tests. Some red sandstones, however, have stable high-temperature (∼ 690°C) components marked by very shallow northerly or southwesterly directions. Five sites in pale red sandstone from the Coleman Member near Elliot Lake give a dip-corrected A direction of D = 216.3°, I = 5.5° (α95 = 6.7°, n = 30), and 17 sites in Lorrain red sandstone near Desbarats give a dip-corrected A direction of D = 5.4°, I = 5.5° (α95 = 5.9°, n = 75). Unfavorable structural attitudes rendered fold tests inconclusive. These very shallow directions may be ascribed to early chemical remanent magnetization (CRM) because (a) some specimens display polarity reversals, (b) such directions are unknown, either as original or as overprint components, in post-Huronian rocks of the region, and (c) a prior site in Coleman red beds gave a high-temperature, shallow NNW direction that is not significantly different from Lorrain A and which a positive conglomerate test suggested is not an overprint. The very shallow directions are near primary directions for the slightly older (2.45 Ga) Matachewan dyke swarm in the region. Lorrain argillic rocks at five sites give a normal component B (T = 670°C, D = 18.6°, I = 59.6°, α95 = 6.1°, n = 16, dip corrected) and a reverse component E (T = 500°C, D = 190.9°, I = −60.9°, α95 = 7.3°, n = 14, in situ), which are close to a prefolding direction carried by magnetite previously identified in Coleman gray argillites (Morris A). However, a primary origin for Morris A is dubious because of the widespread occurrence of overprints carried by magnetite in Coleman gray argillites and because the fold test employed folds formed during the Penokean Orogeny at 1900-1800 Ma. Our results suggest that Morris A/Lorrain B and Lorrain E may data from immediately before and just after Penokean folding, respectively. Hence Coleman-sandstone A and Lorrain A may be better estimates of original directions. Those components and Matachewan paleomagnetic data constrain Huronian paleolatitudes and suggest that Huronian glaciation occurred within 11° and possibly within 4° of the paleoequator.

A palaeoplain that cuts across Lewisian Gneiss in the Cape Wrath area, northwest Scotland, is weathered to depths of 1–6 m beneath fluvial red conglomerates and sandstones of the Applecross Formation of the early Neoproterozoic Torridon Group. Weathered Lewisian rocks are enriched in K 2 O and Fe 2 O 3 , and contain hematite as an alteration product of biotite and magnetite. Palaeomagnetic analysis of the weathering profiles has been carried out to constrain the age of alteration. Thermal step demagnetization of 87 oriented core specimens of biotite-gneiss and amphibolite spanning four profiles at Poll a’ Mhurain and Sheigra reveal a stable, high-temperature component with a mean direction of remanence of D= 149.1°, I =57.2° (α 95 = 5.0°) (corrected for dip of the overlying Applecross strata) that gives a pole at 9.8°S, 199.2°E (dp = 5.3°, dm=7.3°). This direction differs significantly from that for little-weathered Lewisian at those two localities and also from directions for the late Mesoproterozoic Stoer Group. The remanence direction for the weathered rocks is, however, near the dip-corrected high-temperature remanence direction (D= 122.3°, I =50.5°, α 95 =10.8°) obtained by us from the thermal step demagnetization of 39 sandstone specimens of the Applecross Formation in the Cape Wrath area. Furthermore, the direction for the weathered rocks agrees closely with other dip-corrected results for the Torridon Group, such as the detrital remanent magnetization (DRM) mean direction (D= 148.3°, I =59.9°, α 95 =13.8°) for the Applecross Formation on Rum and that for the main outcrop of the Aultbea Formation ( D =139.7°, I =52.6°, α 95 = 14.5°). The concordance of palaeomagnetic results for the sediments and weathered rocks implies that the weathering profiles in the Cape Wrath area acquired their remanence penecontemporaneously with deposition of the Applecross and Aultbea formations. The palaeomagnetic results therefore argue strongly that the weathering profiles are palaeosols of Applecross age ( c. 980 Ma) that formed at a palaeolatitude of 38° and constitute the oldest known palaeosols in the British Isles—views that the weathering is substantially older or younger than Applecross deposition cannot be sustained. Our findings carry implications for Applecross palaeoclimate and source and strengthen the conclusion that atmospheric oxygen was a substantial fraction of its present abundance by early Neoproterozoic time.

Paleotidal records obtained from sedimentary tidal rhythmites may be systematically abbreviated and so may give incorrect paleotidal and paleorotational values. The validity of determined values, including past length of day (l.o.d.), can be assessed by testing for internal self-consistency through application of the laws of celestial mechanics. Three independent values obtained from the ∼620-Ma Elatina-Reynella rhythmites in South Australia (14.1 sidereal months/year, 401 sidereal days/year, and 19.5 years for the lunar nodal period), when employed in different equations that make allowance for lunar and solar tidal effects, each give a lunar semimajor axis in the range of 96.5–96.9% of the present figure. Such self-consistency strongly supports the validity of the derived l.o.d. of 21.9 hours at ∼620 Ma. The validity of the estimated l.o.d. of 20.9 hours at ∼900 Ma (revised value, Big Cottonwood rhythmites, Utah) and of 17.1–18.9 hours at ∼2.5 Ga (Weeli Wolli rhythmites, Western Australia) cannot be assessed in that way because each data set has only one directly determined value. The derived mean rate of lunar retreat of 2.16 cm/year since ∼620 Ma averts a close approach of the Moon at least since 3 Ga and a lower rate of retreat seems likely during the Proterozoic.

Paleomagnetic data for Neoproterozoic glacial deposits in South Australia and elsewhere verify glaciomarine deposition near the paleoequator. Tidal rhythmites from such deposits in South Australia display symmetrical ripples indicating decades of continuous wave activity, and also record the annual oscillation of sea level. In low and moderate latitudes the annual oscillation of sea level results mostly from seasonal changes in heat content of the sea, indicating extensive and long-lived open seas in low latitudes during Neoproterozoic glaciations. Neoproterozoic periglacial sand wedges 3+ m deep, marking polygons 10-30 m across, are closely comparable to periglacial wedges in present high latitudes and imply large (∼40°C) seasonal changes of mean monthly temperature near the paleoequator. Periglacial wedges did not form at high elevations on the Pleistocene equator where temperatures were well below 0°C throughout the year and temperature fluctuations were mainly diurnal, which militates against diurnal fluctuations as the cause of the Neoproterozoic wedges. An extremely large (50%) octupole component of the geomagnetic field is required to make true moderate latitudes appear paleoequatorial, whereas Proterozoic paleomagnetic data suggest a maximum octupole component of ≤30%. A snowball or slushball Earth is difficult to reconcile with open seas and large seasonal temperature-changes in low paleolatitudes. A Proterozoic high obliquity (>54°) resulting from the Moon-producing single giant impact may explain glaciation and strong seasonality on the equator, but a mechanism is required to subsequently reduce the obliquity. At present the Neoproterozoic paleomagnetic and glacial records cannot be reconciled satisfactorily, demanding further wide-ranging research.

A suite of soft-sediment deformation structures occurs in tidal rhythmites of fine sand to silt grade in the late Neoproterozoic (∼600 Ma) Elatina Formation, which is part of the Marinoan glaciogenic succession in the Adelaide foldbelt, South Australia. The structures include: (1) sets of asymmetrical cuspate ridges (γ = 13–50 cm, h = 3–5 cm) formed on bed surfaces and underlain by folds affecting as much as 60 cm thickness of strata; (2) symmetrical and interference ripple forms (γ = 3–15 cm, h = ≤1.5 cm) mostly confined to the troughs between the cuspate ridges and which are underlain by folds, involving up to 20 cm thickness of strata, that commonly parallel the undulations of the bed surface but in places have steepened limbs; (3) rill marks on the flanks of cuspate ridges and some ripple forms. The crests of the cuspate ridges and ripple forms commonly were draped and locally eroded and truncated during overall vertical accretion. The cuspate structures are interpreted as gravity slide deposits that formed after transformation of surficial sediment to a hydroplastic state, possibly by the cyclic stresses generated by storm waves, and its sliding on tidal-delta slopes. The ripple forms resulted from continuing wave activity and were maintained by draping and vertical accretion from unidirectional currents and locally by deposition of supercritical cross-lamination. The further deformation of the cuspate folds, as revealed by palaeomagnetic analyses of the structures, implies additional sliding and/or the differential loading of hydroplastic sediment in the troughs between the cuspate ridges. This study confirms that positive palaeomagnetic fold-tests on several cuspate folds indicate a primary origin for the shallow palaeomagnetic inclination (−5.3°) of the Elatina Formation and hence the equatorial palaeolatitude of late Neoproterozoic glaciation in South Australia.

A new palaeomagnetic study has been conducted on haematitic shales and siltstones of the late Neoproterozoic Bunyeroo Formation in the Adelaide fold belt (Geosyncline), South Australia, which host an extensive horizon of shock-deformed rock fragments and microtektite-like material of probable impact origin. Thermal step demagnetisation of 116 samples of red shale and siltstone from six sections (sites) revealed a high-temperature component with a bedding-corrected site-mean direction of remanence of D = 56.6°, I = 29.3° (α95 = 10.7°) that gives a pole at 18.1°S, 16.3°E (dp = 6.5°, dm = 11.8°). The high-temperature component provides a positive tectonic-fold test (99% level of confidence). The Bunyeroo high-temperature remanence direction is near the remanence direction (D = 50°, I = 40°) indicated by modelling the subsurface magnetic source of the central high-amplitude anomaly at Acraman, Australia's largest confirmed meteorite impact structure 220–350 km west of the Adelaide fold belt, and also is close to the mean direction (D = 48.3°, I = 54.7°, α95 = 5.2°) determined for surface melt rock from Acraman. Statistical tests show that the virtual geomagnetic poles indicated by the directions for the subsurface central magnetic source and surface melt rock at Acraman may be regarded as subsets of the Bunyeroo palaeomagnetic pole position, indicating that the three pole positions are statistically indistinguishable. The results imply that the subsurface magnetic source and surface melt rock acquired their remanence in the ambient geomagnetic field during cooling, after the impact when structural disturbance had ceased, while the Bunyeroo Formation was accumulating. The agreement among the various remanence directions argues strongly that the ejecta horizon in the Bunyeroo Formation was derived from Acraman. The present findings confirm that the Acraman impact occurred in the late Neoproterozoic, about 590 Ma, which is the age of the Bunyeroo Formation provided by Rb Sr whole-rock shale dating of equivalent and contiguous strata in the Adelaide fold belt region. The Bunyeroo palaeomagnetic data give a palaeolatitude of ∼ 15°, indicating a low palaeolatitude for the Acraman impact and supporting other findings that the Adelaide fold belt occupied low to equatorial palaeolatitudes during the late Neoproterozoic.

The stratigraphic position and claimed glacial origin of the diamictitic ‘Gangau tilloid’ in central India have long been controversial. Our study shows that the ∼ 50-m-thick tilloid overlies the Palaeoproterozoic Bijawar Group with angular unconformity and forms the base of the Mesoproterozoic (∼ 1200–1400 Ma) Vindhyan Semri Group. The tilloid contains clasts up to 1 m across, virtually all of stable siliceous lithologies like those of the Bijawar Group, supported by a fine-grained haematitic matrix. Glacially faceted and striated clasts were not observed. The tilloid displays much disruption of beds, and pebble-sized clasts of lamellar and nodular chert-quartz underwent brittle fracture and plastic puckering during deposition. Values are high for SiO2 (68.8–85.5%) and Fe2O3 (7.73–20.1%), and low for Al2O3 (1.03–5.50%) and other elements. The composition of the tilloid is similar to that of laterites formed on sandstone bedrock. Thermal step demagnetisation of 91 core samples from seven sites spanning the tilloid revealed three components: a low-temperature Tertiary component A, an intermediate-temperature steep downward component B and, more rarely, a high-temperature less steep component C. Haematite is the likely carrier of the remanence, interpreted as chemical remanent magnetisation. C may be older than B and date from near the time of deposition. Bedding-corrected C has a direction of D = 161.4°, I = 63.2° (a95 = 12.7°) that gives a pole at 18.2°S, 93.4°E (dp = 15.8°, dm = 20.0°). The pole plots near 1200 Ma on the Australian Precambrian apparent polar wander path using the Veevers et al. (1991) reconstruction for East Gondwanaland. The sedimentology, composition and geochemistry of the Gangau tilloid accord with deposition by continental debris-flows derived mainly from a ferruginous regolith formed on sedimentary rocks. Zoned chert-quartz bodies may have been precipitated in shrinkage cracks and voids in the lower, saturated zone of the regolith, and possibly also as thin beds or crusts of silica within the drainage system. The inferred ferruginous weathering in the source area favours warm and humid conditions with a dry season, and precipitation of silica in the regolith implies seasonal or longer wet and dry intervals. Debris-flow activity indicates brief episodes of abundant runoff. There is no evidence of glaciation. Production of abundant ferric iron in the source regolith implies the presence of appreciable atmospheric oxygen by ∼ 1200–1400 Ma.

As medical technology has improved, greater numbers of previously infertile couples have been able to conceive. Evidence of idealized views of parenting and unrealistic expectations for their children has fueled speculation about a possible negative impact of infertility on parent-child relationships. We evaluated the impact of past infertility on parent and child adjustment. Women with a history of infertility (N = 45) or who had voluntarily delayed pregnancy (n = 45) and who had a child 5 years old or younger completed the Parenting Stress Index (PSI) and Child Behavior Checklist. Results showed that mothers who were at one time infertile did not report significantly greater adjustment difficulties for themselves or their children than a comparable group of parents who voluntarily delayed pregnancy. The control group did report significantly higher scores on several subscales of the PSI, indicating that they felt more restricted, isolated, and unsupported than the group with a history of infertility. Ne...

New palaeomagnetic analyses have been carried out for the Neoproterozoic (650-600 Ma) Elatina Formation, an important redbed unit of the Marinoan glaciogenic sequence in the Adelaide Geosyncline, South Australia, and flat-lying equivalent facies on the adjacent cratonic Stuart Shelf and Torrens Hinge Zone. The Marinoan rocks display strong evidence of marine glacial deposition, and coeval periglacial sand wedges in permafrost regolith on the Stuart Shelf indicate in-situ cold climate near sea level and marked seasonality. The palaeomagnetic data define a palaeopole for the formation and indicate that Marinoan glaciation, including permafrost, grounded glaciers and marine glacial deposition, occurred near the palaeoequator. Rocks analysed include 97 oriented outcrop samples from 15 sites at three widely separated sections (∼ 65–115 m thick) of gently folded and unmetamorphosed sandstone, siltstone and tillite spanning the Elatina Formation in the Central Flinders Zone of the Adelaide Geosyncline, soft-sediment folds from tidal rhythmites, and 60 specimens from 54 core samples from six deep drillholes on the Stuart Shelf and Torrens Hinge Zone. The most stable remanence components were only completely demagnetised by 685°C, indicating that haematite is the likely carrier of the remanent magnetisation. This conclusion is supported by the presence of ultrafine haematitic pigment coating clastic grains and filling interstices in the rocks. The observation of mixed polarities within some sandstone samples suggests that such lithologies acquired their remamence as chemical remanent magnetisation (CRM). A positive fold test on syndepositional soft-sediment folds in tidal rhythmites confirms that the rhythmites acquired a detrital remanent magnetisation (DRM) by the settling of haematite grains from suspension in quiet waters. Concordant palaeomagnetic directions determined for the rhythmites and other facies of the Elatina Formation show that the formation acquired its CRM close to the time of deposition. The existence of polarity reversals within a stratigraphic section and within some samples therefore argues strongly for the identification of a dipole field axis and the sufficient averaging of secular variation to define a palaeopole for the formation. The palaeopole derived from the oriented sample results (structurally corrected) is located at 52.4°S, 347.1°E ( d p = 3.7 °, d m = 7.4°); this pole position is consistent with the Neoproterozoic apparent polar wander path for Australia. The overall formation mean direction determined from the sample results (structurally corrected) has a declination of 197.3° and an inclination of −5.3° (α 95 = 7.4°), and indicates a mean palaeolatitude of deposition of 2.7° ± 3.7°N. These results accord with the virtual geomagnetic pole previously determined for tidal rhythmites of the Elatina Formation and provide the strongest evidence yet for the equatorial palaeolatitude of Neoproterozoic glaciation. The palaeomagnetic results, together with geological observations for Marinoan glaciogenic rocks, therefore confirm the Neoproterozoic (pre-Ediacaran, ≥ 590 Ma) climatic paradox in South Australia: frigid strongly seasonal climate, permafrost, and grounded glaciers near sea level in equatorial palaeolatitudes . Resolution of this paradox may illuminate Precambrian planetary dynamics and the change in global state during the Ediacaran.

Pediatricians are often asked to advise parents who are having difficulty managing the oppositional behaviors of their toddlers and preschool-age children. A large number of articles provide advice to pediatricians and parents on effective disciplinary strategies. However, despite the fact that verbal explanations, reasoning, and instructions are commonly used by parents, few articles directly address the use of these strategies to affect children's behavior. In this paper, we review studies that explicitly investigate the ability of adults' verbal explanations or instructions to alter the behavior of young children. These studies suggest that under most circumstances, verbal explanations and instructions are not effective in changing young children's problem behaviors. We then discuss how theories in developmental and behavioral psychology help explain the limitations of using verbal reasoning and instructions to change young children's problem behaviors. Finally, we provide some recommendations for parents on the use of verbal explanations and instructions in disciplining young children.

In the geological past when the Earth's decelerating rotation passed through the critical length of day of ∼ 22.2 h, the free nutation or ‘tipping’ of the fluid core (for a core shape in hydrostatic equilibrium) would have resonated precisely with the Earth's retrograde annual forced nutation caused by solar torques. This annual resonance may have caused orders-of-magnitude amplification of core rotation and velocity of core motions, leading to temperature increase and heat release near the core-mantle boundary, instability of the D″ thermal boundary layer at the base of the mantle, and the upwelling of deep mantle plumes. Neoproterozoic palaeotidal data indicate 21.9 ± 0.4 h/day at ∼ 620 Ma, thus placing the critical length of day of ∼ 22.2 h and core resonance at 530 ± 100 Ma. A core shape departing by ±5% from its equilibrium value places resonance in the interval 530 ± 250 Ma. The one distinctive, major tectonothermal event in the interval 530 ± 250 Ma was that of ‘late Pan-African’ age, which affected much of Gondwana during the late Neoproterozoic-early Palaeozoic. This tectonothermal activity, which peaked between ∼ 570 and ∼ 500 Ma, was marked by high temperatures at mid-crustal levels and elevated heat flow, widespread granulite facies metamorphism and crustal reworking and anatexis, commonly in the absence of obvious pervasive deformation, extensive epeirogenic uplift and extrusion of flood basalts; such features indicate an intense crustal heating event that may be ascribed to mantle plumes and hotspots. Furthermore, flood volcanism and rifting in Laurentia during the late Neoproterozoic-early Palaeozoic suggest the coeval upwelling of mantle plumes that led to continental breakup including the opening of the Iapetus Ocean. The apparent global peak in plume activity between ∼ 570 and ∼ 500 Ma may reflect an increase in core-mantle heat flux and instability of D″, caused by the annual resonance of the fluid core (for a core shape in or near hydrostatic equilibrium). The core evidently underwent stronger resonances with the semi-annual and 1/3-annual forced nutations at widely spaced times during the Archaean, when the length of day was approximately 17.7 ± 0.4 h and 15.4 ± 0.4 h, respectively; these two resonances probably caused much greater increases in the velocity and amplitude of core motions and in core-mantle heat flux than occurred during the annual resonance. Proterozoic palaeorotational data suggest that the very strong semi-annual resonance may correlate with the worldwide tectonothermal event at ∼ 2700 Ma; this event is marked by widespread mantle and crustal anatexis, granitoid intrusion and the extrusion of flood basalts and komatiites, and has been ascribed to the upwelling of high-temperature plumes from the core-mantle boundary. The hypothesis that major tectonothermal reworking events may have resulted from thermal plumes generated at the core-mantle boundary in response to resonances of the fluid core for a tidally decelerating Earth may be tested by the acquisition of high quality palaeorotational data for the early Palaeoproterozoic and Archaean.