A certain shyness about research misconduct in the UK

Since Earth Pages was launched at the start of the 21st century there have been highly publicised cases of gross misconduct by researchers, including plagiarism, ‘massaging ‘data and even sabotaging the work of others, as well as lesser cases where publications were withdrawn or removed from journals. The most notorious have been from the USA, Japan, the Netherlands and a number of other advanced countries. But sharp practices in science are not well known in the UK; indeed I can’t recollect more than one case that reached the same degree of coverage as the most notorious instances. Yet, in 2009, Daniele Fanelli of the University of Edinbugh reported the results of her analysis of accessible information from the UK about this matter. She found that about 2% of British scientists, who had been interviewed or answered questionnaires, answered ‘Yes’ when asked if they ever fabricated or falsified research data, or if they altered or modified results to improve the outcome. Up to one third admitted other questionable practices or knew of them having been committed by colleagues. Fanelli doesn’t refer to more grievous matters such as sabotage or exploitation of students’ work.

The silence from British Universities on research misconduct has become such an embarrassment that it was a subject of an Editorial and a News In Focus Report in the 21 May issue of Nature . While there are guidelines that urge British universities to publish annual reports of their investigations into misconduct, for 2013-14 only 12 such reports have been published : of the 88 universities contacted by the informal UK Research Integrity Office, 30 institutions responded to UKRIO’s survey. These reports covered 21 investigations, mostly unspecified, with 5 cases of plagiarism, 2 of falsification, 2 concerning authorship, 1 of fabrication and 1 breach of confidentiality. Three were upheld and 3 are pending.

These figures speak loudly for themselves: misconduct by researchers (and academics in general) is something that the halls of British academe ‘dinnae care to speak aboot’. As the author of UKRIO’s survey observed, ‘It’s just not credible’, although many of the universities that she contacted claim that such reports were in progress. A likely story… We all know that the ‘filthy snout’ (Tom Wolfe The Bonfire of the Vanities) does ‘come popping to the surface’, but is buried in confidentiality by university Research Committees, leaving any victims dangling in a sorry psychological state and allowing journals’ peer review system to catch any perpetrators before they reach the press, which it is rarely able to do. It takes a case as severe as that of Andrew Wakefield’s fraudulent 1998 paper in the Lancet associating the MMR vaccine with autism to see justice done.

Snowball Earth events pinned down

The Period that lasted from 850 to 635 million years ago, the Cryogenian, takes its name from evidence for two and perhaps three episodes of glaciation at low latitudes. It has been suggested that, in some way, they were instrumental in the decisive stage of biological evolution from which metazoan eukaryotes emerged: the spectacular Ediacaran fossil assemblages follow on the heels of the last such event Although controversies about the reality of tropical latitudes experiencing ice caps have died away, there remains the issue of synchronicity of such frigid events on all continents, which is the central feature of so-called ‘Snowball Earth’ events. While each continent does reveal evidence for two low latitude glaciations – the Sturtian (~710 Ma) and the later Marinoan (~635 Ma) – in the form of diamictites (sediments probably dropped from floating ice and ice caps) it has proved difficult to date their start and duration. That is, the cold episodes may have been diachronous – similar conditions occurring at different localities at different times. Geochronology has, however, moved on since the early disputes over Snowball Earths and more reliable and precise dates for beginnings and ends are possible and have been achieved in several places (Rooney, A.D. et al. 2015. A Cryogenian chronology: Two long-lasting synchronous Neoproterozoic glaciations. Geology, v. 43, p. 459-462).

One computer simulation of conditions during a...

Computer simulation of conditions during a Snowball Earth period. (credit: Macmillan Publishers Ltd: Hyde et al., Nature 405:425-429, 2000)

Rooney and colleagues from Harvard and the University of Houston in the USA used rhenium-osmium radiometric dating in Canada, Zambia and Mongolia. The Re-Os method is especially useful for sulfide minerals as in the pyritic black shales that occur extensively in the Cryogenian, generally preceding and following the glacial diamictites and their distinctive carbonate caps. Combined with a few ages obtained by other workers using the Re-Os method and U-Pb dating of volcanic units that fortuitously occur immediately beneath or within diamictites, Rooney et al. establish coincident start and stop dates and thus durations of both the Sturtian and Marinoan glacial events: 717 to 660 Ma and 640 to 635 Ma respectively on all three continents. Their data is also said to refute the global extent and even the very existence of an earlier, Kaigas glacial event (~740 Ma) previous recorded from diamictites in Namibia, the Congo, Canada and central Asia. This assertion is based on the absence of diamictites with that age in the area that they studied in Canada and their own dating of a diamictite in Zambia, which is one that others assigned to the Kaigas event

The dating is convincing evidence for global glaciation on land and continental margins in the Cryogenian, as all the dates are from areas based on older continental crust. But the concept of Snowball Earth, in its extreme form, is that the oceans were ice-capped too as the name suggests, which remains to be convincingly demonstrated. That would only be achieved by suitably dated diamictites located on obducted oceanic crust in an ophiolite complex. Moreover, there are plenty more Cryogenian diamictites on other palaeo-continents and formed at different palaeolatitudes that remain to be dated (see here)

Earthquake hazard news

Assessments of seismic risk have relied until recently on records of destructive earthquakes going back centuries and their relationship to tectonic features, mainly active faults. They usually predict up to 50 years ahead. The US Geological Survey has now shifted focus to very recent records mainly of small to medium tremors, some of which have appeared in what are tectonically stable areas as well as the background seismicity in tectonically restless regions. This enables the short-term risk (around one year) to be examined. To the scientists’ surprise, the new modelling completely changes regional maps of seismic risk. The probabilities in the short-term of potentially dangerous ground movements in 17 oil- and gas-rich areas rival those in areas threatened by continual, tectonic jostling, such as California. The new ‘hot spots’ relate to industrial activity, primarily the disposal of wastewater from petroleum operations by pumping it into deep aquifers.

USGS map highlighting short-term earthquake risk zones. Blue boxes indicate areas with induced earthquakes (source: US Geological Survey)

USGS map highlighting short-term earthquake risk zones. Blue boxes indicate areas with induced earthquakes (source: US Geological Survey)

Fluid injection increases hydrostatic pressure in aquifers and also in the spaces associated with once inactive fault and fracture systems. All parts of the crust are stressed to some extent but the presence of fluids and over-pressuring increases the tendency for rock failure. While anti-fracking campaigners have focussed partly on seismic risk – fracking has caused tremors around magnitudes 2 to 3 – the process is a rapid one-off injection involving small fluid volumes compared with petroleum waste-water disposal. All petroleum production carries water as well as oil and gas to wellheads. Coming from great depth it is formation water held in pores since sedimentary deposition, which is environmentally damaging because of its high content of dissolved salts and elevated temperature. Environmental protection demands that disposal must return it to depth.

The main worry is that waste water disposal might trigger movements with magnitudes up to 7.0: in 2011 a magnitude 5.6 earthquake hit a town in oil-producing Oklahoma and damaged many buildings. Currently, US building regulations rely on earthquake risk maps that consider a 50-year timescale, but they take little account of industrially induced seismicity. So the new data is likely to cause quite a stir. These are changing times, however, as the oil price fluctuates wildly. So production may well shift from field to field seeking sustainable rates of profit, and induced seismicity may well change as a result.

None of these areas are likely to experience the horrors of the 25 April 2015 magnitude 7.8 earthquake in Nepal. However, it also occurred in an area expected to be relatively stable compared with the rest of the Himalayan region. The only previous major tremor there was recorded in the 14th century. This supposedly ‘low-risk’ area overlies a zone in which small tremors or microearthquakes occur all the time. Such zones – and this one extends along much of the length of the Himalaya – seem to mark where fault depths are large enough for displacements to take place continually by plastic flow, thereby relieving stresses. Most of the large earthquakes have taken place south of the microseismic zone where the shallow parts of the Indian plate are brittle and have become locked. The recent event is raising concerns that it is a precursor of further large earthquakes in Nepal. Its capital Kathmandu is especially susceptible as it is partly founded on lake sediments that easily liquefy.

Note added: 13 May 2015. Nepal suffered another major shock (magnitude 7.3) on 12 May in the vicinity of Mount Everest. It too seems to have occurred in the zone of microearthquakes formerly thought to mark a zone where the crust fails continually bu plastic deformation thereby relieving stresses. Kathmandu was this time at the edge of the shake zone

Two large, reorganised landscapes

Where tectonic processes proceed quickly it is only to be expected that the land surface undergoes dramatic changes and that big features form. Exactly which processes lay behind very striking landforms may have been worked out long ago; or old ideas from the heyday of geomorphology have perhaps lingered longer than they should. Two tectonically active regions that have a long history of study are the Himalaya and Iceland: one a model of long-lived and rapid uplift driven by collisional tectonics; the other likewise, as a product of extension and rapid build-up of flood basalt flows. Major features of both have been shown to be not quite what they seem.
Substantial parts of the India-Asia collision zone contain broad patches of high, low-relief plateaus separated by deeply incised river gorges. In its eastern parts rise 3 of the largest rivers in SE Asia: the Yangtse; the Mekong and the Salween, which flow roughly parallel to the east and south-east for about 1000 km from their sources in the Tibetan Plateau. Their trajectories partly follow some enormous strike-slip fault that accommodated the relative motion of two continent-bearing plates over the last 50 million years. As well as the crustal thickening that attended the collision, vast amounts of uplifted material have been eroded from the three major gorges. Thickening and unloading have been the key to producing the largest tracts of high land on the planet. Yet between the gorges and their many tributaries in the eastern part of the collision zone are many tracts of high land with only moderate relief rather than sharp ridges. Because the Eurasian plate prior to India’s impact might reasonably be expected to have been only moderately high, if not low lying, and with a mature and muted landscape, a long-lived theory has been that these elevated plateaus are uplifted relics of this former landscape that were dissected by progressively deepening river incision. Much the same idea has been applied to similar mega features, and even coincident peaks in more completely eroded highlands.

Drainage basins of the Yangtse, Mekong and Salween rivers, with low-relief surfaces in buff and cream. Figure 1 in Yang et al. 2015 (credit: Nature)

Drainage basins of the Yangtse, Mekong and Salween rivers, with low-relief surfaces in buff and cream. Figure 1 in Yang et al. 2015 (credit: Nature)

In the India-Asian collision zone the supposedly ‘relic’ plateaus have been used to reconstruct the pre-collision land surface and the degree of bulging it has undergone since. However, the advent of accurate digital terrain elevation data has enabled the modelling of not only the large rivers but also of the tributary streams that make up major drainage. As well as the directional aspects of drainages their along-channel slopes can be analysed (Yong, R. et al. 2015. In situ low-relief landscape formation as a result of river network disruption. Nature, v. 520, p. 526-529). Rong Yang of the Swiss Federal Institute of Technology and colleagues from the same department and Ben-Gurion University of the Negev, Israel have been able to show that matters are far more complex than once believed. The tributary drainages of the Yangtse, Mekong and Salween gorges appear to have been repeatedly been disrupted by the complexities of deformation. One important factor has been drainage capture or piracy, in which drainages with greater energy erode towards the heads of their catchments until they intercept a major drainage in another sub-basin, thereby ‘stealing’ the energy of the water that it carries. The ‘pirate’ stream then erodes more powerfully in its lower reaches, whereas the basin burgled of much of its energy becomes more sluggishly evolving thereafter and increasingly left anomalous high in the regional terrain: it evolves to liken what previously it had been supposed to be – a relic of the pre-collision landscape.
Many of the rivers in Iceland occupy gorges that contain a succession of large waterfalls. Upstream of each is a wide rock terrace, and downstream the gorge is eroded into such a terrace. Much of Iceland is composed of lava flows piled one above another, as befits the only substantial land that straddles a constructive plate margin – the mid-Atlantic Ridge. Being famous also for its substantial ice caps that are relics of one far larger during the last glacial maximum, it has proved irresistible for geomorphologists to assign the gorge-fall-terrace repetition to gradual uplift due to isostatic rebound as the former ice cap melted and unloaded the underlying lithosphere. As relative sea-level fell each river gained more gravitational potential energy to cut back up its channel, which resulted in a succession of upstream migrating waterfalls and gorges below them. Individual lava flows, being highly resistant to abrasion cease to be affected once cut by a gorge; hence the terraces. But it is now possible to establish the date when each terrace first became exposed to cosmic-ray bombardment, using the amount of cosmogenic 3He that has accumulated in the basalts that form the terrace surfaces (Baynes, E.R. et al. 2015. Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland. Proceedings of the National Academy of Science, doi:10.1073/pnas.1415443112).

Valley of Jökulsá á Fjöllum past Dettifoss, Jö...

Gorge incised in basalt flows, Jökulsárgljúfur National Park, Iceland (credit: Wikipedia)

The British-German team from the University of Edinburgh and Deutsches GeoForschungsZentrum, Potsdam worked on terraces of the Jökulsárgljúfur canyon, discovering that three terraces formed abruptly in the Holocene, at 9, 5 and 2 ka ago, with no evidence for any gradual erosion by abrasion. Each terrace was cut suddenly, probably aided by the highly jointed nature of the overlying lava flow that would encourage toppling of blocks given sufficient energy. The team suggests that each represents not stages in uplift, but individual megafloods, perhaps caused by catastrophic glacial melting during subglacial eruptions or failures of dams formed by moraines or ice lobes.

What followed the Giant Impact (read Lord Mayor’s Show)?

The dominance of the Lunar Highlands by feldspar-rich anorthosites, which form when feldspars that crystallise from magmas float because of their lower density, gave rise to the idea that the Moon initially formed as a totally molten mass. That this probably resulted because the early Earth collided with a Mars-sized protoplanet stems from the almost identical chemical composition of the lunar and terrestrial mantles, as worked out from the composition of younger basalts derived from both, together with the vast energy needed to support a large molten planetary body condensing from a plasma cloud orbiting the Earth. Such a giant impact is also implicated in the final stages of core formation within the Earth.

Artist's depiction of the giant impact that is...

Artist’s depiction (after William K. Hartmann) of the giant impact that is hypothesized to have formed the Moon. (credit: Wikipedia)

A core formed from molten iron alloyed with nickel would have acted as a chemical attractor for all other elements that have an affinity for metallic iron: the siderophile elements, such as gold and platinum. Yet the chemistry of post-moon formation basaltic melts derived from the Earth’s mantle contain considerably more of these elements than expected, a feature that has led geochemists to wonder whether a large proportion of the mantle arrived – or was accreted – after the giant impact.

A tool that has proved useful in geochemistry on the scale of entire planets – well, just the Earth and Moon so far – is measuring the isotopic composition of tungsten, a lithophile metal that has great affinity for silicates. One isotope is 182W that forms when a radioactive isotope of hafnium (182Hf) decays. The proportion of 182W relative to other tungsten isotopes has been shown to be about the same in Lunar Highland anorthosites as it is in the Earth’s mantle. This feature is believed to reflect Moon formation and its solidification after the parent 182Hf had all decayed away: the decay has a half-life of about 9 Ma and after 60 Ma since the formation of the Solar System (and a nearby supernova that both triggered it and flung unstable isotopes such as 182Hf into what became the Solar nebula) vanishingly small amounts would remain.

Oddly, two papers on tungsten and Earth-Moon evolution, having much the same aims, using similar, newly refined methods and with similar results appeared in the same recent issue of Nature (Touboul, M. et al. 2015. Tungsten isotopic evidence for disproportional late accretion to the Earth and Moon. Nature, v. 520, p. 530-533. Kruijer, T.S. et al. 2015. Lunar tungsten isotopic evidence for the late veneer. Nature, v. 520, p. 534-537). The two of them present analyses of glasses produced by large impacts into the lunar surface and probably the mantle, which flung them all over the place, maintaining the commonality of the ventures that might be explained by there being a limited number of suitable Apollo samples. Both report an excess of 182W in the lunar materials: indeed, almost the same excess given the methodological precisions. And, both conclude that Moon and Earth were identical just after formation, with a disproportional degree of later accretion of Solar nebula material to the Earth and Moon.

So, there we have it: it does look as if Earth continued to grow after it was whacked, and there is confirmation. Both papers conclude, perhaps predictably, that the early Solar System was a violent place about which there is much yet to be learned…

St Paul and the meteorite?

Dateline: Chelyabinsk, Russia 09.20 15 February 2013. As in many parts of Russia drivers in this Oblast in the Urals Economic District use an in-car camera during rush hour, hopefully to have proof of innocence in the event of a traffic accident. On this day, such cameras recorded a massive fireball streaking low across a clear, frosty sky. Some people on foot were temporarily blinded by its light, about 4 times that sunlight, and others were thrown off their feet by a large shock wave. Travelling at about 20 km s-1 the fireball exploded, the blast shattering windows where people were gazing at the remarkable sight, about 1500 needing medical treatment. This event is the first in modern times to record the atmospheric entry of a superbolide and air blast, probably similar to what happened in the deserted area of Tunguska in Siberia on 30 June 1908.

Meteor trail and fireball seen over industrial estate in Chelyabinsk, Russia (credit: Russia Today)

Meteor trail and fireball seen over industrial estate in Chelyabinsk, Russia (credit: Russia Today)

Cut to the Levant in the 1st century of the Common Era: on the road to Damascus a Jewish fundamentalist with Roman citizenship, sworn to destroy the early Christian movement, is on a mission to arrest Christians and take them in chains to Jerusalem. Saul witnesses a great light in the sky and a deafening sound that he believes is the voice of Jesus, saying ‘Saul, Saul, why persecutest thou me?’(Acts 9:4). He is flung off his feet, struck blind and convinced of the error of his calling. Three days later, in Damascus ‘…there fell from his eyes as it had been scales: and he received sight forthwith, and arose, and was baptized’ (Acts 9:18), taking the name Paul.

The conversion of Saul by Michaelangelo

The conversion of Saul by Michaelangelo

William Hartmann of the Planetary Science Institute at the University of Arizona, among the first planetary scientists to propose the giant impact origin for the Moon (see next item) and in his case to visualise it in a famous painting, has drawn a somewhat obvious hypothesis linking the two events (Hartmann, W.K. 2015. Chelyabinsk, Zond IV, and a possible first-century fireball of historical importance. Meteoritics and Planetary Science, v. 50, p. 368-381: doi: 10.1111/maps.12428). These days such a scary observation is easily rationalised as a natural phenomenon, but in earlier times Hartmann believes such a shock would have convinced witness of the almighty power of the supernatural ‘in terms of current cultural conceptions’. He suggests that Saul of Tarsus may, at the time, have been struggling with his conscience about his attacks on his countrymen: hence his conversion. The phrase ‘ scales fell from his eyes’ has entered common parlance for sudden changes in mental state and attitude: in fact it matches an outcome of severe photokeratitis of the eye’s epithelial coating, the dead tissue eventually becoming detached, when clear sight is restored to some sufferers.
While claiming to have no intention of undermining anyone’s spiritual beliefs, Hartmann suggests that such rare and spectacular events are capable of having emotionally changed influential figures of the past and thereby re-routing the course of history. Hartmann cites modern cases of lesser bolide-entry phenomena, such as destruction of satellites over the US and Russia, which some witnesses misreported as rockets with lighted windows; i.e. UFOs. There are plenty of medieval cases where spiritual connotations were widely attached to strange natural phenomena. I have heard accounts from people living in Asmara, capital of Eritrea, who ascribed saintly intervention to a full solar halo with sun dogs connected by cruciform arcs on a misty morning in 1991. This occurred a few days before the occupying Ethiopian forces surrendered to Eritrean nationalist forces whose struggle for self determination had lasted for the previous three decades.

The dinosaur they could not kill: Brontosaurus is back

It would be pretty safe to say that everyone has heard of Brontosaurus, but in the 1970s the genus vanished from the palaeobiology lexicon. The ‘Bone Wars’ of post-Civil War US palaeontology stemmed from the astonishing prices that dinosaur skeletons fetched. The frenzy of competition to fill museums unearthed hundreds of specimens, but the financial enthusiasm did not extend to painstaking anatomy. Finding a new genus meant further profit so a slapdash approach to taxonomy might pay well. So it did with the dinosaur family Diplodocidae for Othniel Marsh, one of the fossil marauders. He along with his main competitor, Edward Cope, was a wizard fossicker, but lacked incentive to properly describe what he unearthed. In 1877 Marsh published a brief note about a new genus that he called Apatosaurus, then hurried off to for more booty. Two years later he returned from the field with another monster reptile, and casually made a brief case for the ‘Thunder Lizard’, Brontosaurus. Unlike his usage of ‘Deceptive Lizard’ for Apatosaurus, the English translation of Brontosaurus caught the public imagination and lingers to this day as the archetype for a mighty yet gentle, extinct beast. Yet, professional palaeontologists were soon onto the lax ways of Marsh and Cope, and by 1903 deemed Brontosaurus to be taxonomically indistinguishable from Apatosaurus, and as far as science was concerned the ‘Thunder Lizard’ was no more.

Illustration of a Brontosaurus (nowadays calle...

Artist’s impression of a Brontosaurus . The idea that it was wholly or mostly aquatic is now considered outdated. (credit: Wikipedia)

But, the legacy of frenzied fossil collecting of a century or more ago is huge collections that never made it to display, which form rich pickings for latter-day palaeontologists with all kinds of anatomical tools now at their disposal: the stuff of almost endless graduate studies. Emanuel Tschopp of the New University of Lisbon with colleagues took up the challenge of the Diplodocidae by examining 49 named specimens and 32 from closely related specimens as controls, measuring up to 477 skeletal features (Tschopp, E. et al. 2015. A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ, v. 3, doi10.771/peerj.857). An unintended consequence was their discovery that 6 specimens of what had become Apatosaurus excelsus (formerly Marsh’s Brontosaurus) differed from all other members of its genus in 12 or more key characteristics. It seems to taxonomists a little unfair that Brontosaurus should not be resurrected, and that looks likely.

Had this been about almost any other group of fossils, with the exception perhaps of the ever-popular tyrannosaurs, the lengthy paper would have passed unnoticed except by specialist palaeontologists. In a little over a week the open-access publication had more than 17 thousand views and 3300 copies were downloaded.

See also: Balter, M. 2015. Bully for Brontosaurus. Science, v. 348, p. 168

Magma rushed into largest layered intrusion

Chances are that the platinum in the catalytic converter that helps prevent your car emitting toxic gases in its exhaust fumes came from a vast igneous intrusion in South Africa known as the Bushveldt complex. The world’s most important source of noble metals formed by repeated differentiation of huge volumes of mafic magma to form thin, dense layers rich in sulfides, platinum group metals and chromium ore set in very thick layers of barren gabbro and other mafic to ultramafic rock. The intrusion is exposed over an area the size of Ireland and formed about 2 billion years ago. Its 370 000 to 600 000 km3 volume suggests that it was the magma chamber that fed flood basalts that erosion has since eroded away. Successive pulses of basaltic magma built up a total thickness of about 8 kilometres of layered rock.

English: black Chromitite and grey anorthosite...

Layered igneous rocks in the Bushveld Complex (credit: Wikipedia)

The final product of the Bushveldt differentiation process was minute pockets of material of more felsic composition trapped within overwhelmingly larger amounts of gabbro. One of the elements that ended up in these roughly granitic inclusions was zirconium that mafic minerals are unable to accommodate while basaltic magma is crystallising. That formed minute crystals of the mineral zircon (ZrSiO4) in the residual pockets, which in turn locked up a variety of other elements, including uranium. Zircon can be dated using uranium’s radioactive decay to form lead isotopes, its refusal to enter chemical reactions after its crystallisation makes U/Pb dates of zircon among the most reliable available for geochronology and the precision of such dates has become increasingly exquisite as mass spectrometry has improved. So, the Bushveldt complex now has among the best records of magma chamber evolution (Zeh, A. et al. 2015. The Bushveld Complex was emplaced and cooled in less than one million years – results of zirconology, and geotectonic implications. Earth and Planetary Science Letters, v. 418, p. 103-114).

Like a number of younger large igneous provinces, the Bushveldt complex took a very short time to form, about 950 thousand years at 2055 Ma ago. That is from magma emplacement to final crystallization when the zircon ages were set, so the accumulation of magma probably took only 100 thousand years. This suggests that magma blurted into the lower crust at an average rate of around 5 cubic kilometers per year, and quite probably even faster if the magmatism was episodic. It requires a major stretch of the imagination to suggest that this could have occurred by some passive process. Instead, the authors have suggested that while a plume of mantle material rose from well below the lithosphere a large slab of lower lithosphere, formed from dense eclogite, broke off and literally fell into the deeper mantle. The resulting changes in stress in the lower lithosphere would have acted as a pump to drive the plume upwards, causing it to melt as pressure dropped, and to squirt magma into the overlying continental crust. Although the authors do not mention it, this is reminiscent of the idea of large igneous provinces having sufficient power to eject large masses from the Earth’s surface: the Verneshot theory, recently exhumed in late 2014. The main difference is that the originators of the Verneshot theory appealed to explosive gas release.

A new explanation for banded iron formations (BIFs)

The main source for iron and steel has for more than half a century been Precambrian rock characterised by intricate interlayering of silica- and iron oxide-rich sediments known as banded iron formations or BIFs. They always appear in what were shallow-water parts of Precambrian sedimentary basins. Although much the same kind of material turns up in sequences from 3.8 to 0.6 Ga, by far the largest accumulations date from 2.6 to 1.8 Ga, epitomised by the vast BIFs of the Palaeoproterozoic Hamersley Basin in Western Australia. This peak of iron-ore deposition brackets the time (~2.4 Ga) when world-wide evidence suggests that the Earth’s atmosphere first acquired tangible amounts of free oxygen: the so-called ‘Great Oxidation Event’. Yet the preservation of such enormous amounts of oxidised iron compounds in BIFs is paradoxical for two reasons: the amount of freely available atmospheric oxygen at their acme was far lower than today; had the oceans contained much oxygen, dissolved ions of reduced Fe-2 would not have been able to pervade seawater as they had to for BIFs to have accumulated in shallow water. Iron-rich ocean water demands that its chemical state was highly reducing.

Oblique view of an open pit mine in banded iron formation at Mount Tom Price, Hamersley region Western Australia (Credit Google earth)

Oblique view of an open pit mine in banded iron formation at Mount Tom Price, Hamersley region Western Australia (Credit Google earth)

The paradox of highly oxidised sediments being deposited when oceans were highly reduced was resolved, or seemed to have been, in the late 20th century. It involved a hypothesis that reduced, Fe-rich water entered shallow, restricted basins where photosynthetic organisms – probably cyanobacteria – produced localised enrichments in dissolved oxygen so that the iron precipitated to form BIFs. Later work revealed oddities that seemed to suggest some direct role for the organisms themselves, a contradictory role for the co-dominant silica-rich cherty layers and even that another kind of bacteria that does not produce oxygen directly may have deposited oxidised iron minerals. Much of the research focussed on the Hamersley BIF deposits, and it comes as no surprise that another twist in the BIF saga has recently emerged from the same, enormous repository of evidence (Rasmussen, B. et al. 2015. Precipitation of iron silicate nanoparticles in early Precambrian oceans marks Earth’s first iron age. Geology, v. 43, p. 303-306).

The cherty laminations have received a great deal less attention than the iron oxides. It turns out that they are heaving with minute particles of iron silicate. These are mainly the minerals stilpnomelane [K(Fe,Mg)8(Si, Al)12(O, OH)27] and greenalite [(Fe)2–3Si2O5(OH)4] that account for up to 10% of the chert. They suggest that ferruginous, silica-enriched seawater continually precipitated a mixture of iron silicate and silica, with cyclical increases in the amount of iron-silicate. Being such a tiny size the nanoparticles would have had a very high surface area relative to their mass and would therefore have been highly reactive. The authors suggest that the present mineralogy of BIFs, which includes iron carbonates and, in some cases, sulfides as well as oxides may have resulted from post-depositional mineral reactions. Much the same features occur in 3.46 Ga Archaean BIFs at Marble Bar in Western Australia that are almost a billion years older that the Hamersley deposits, suggesting that a direct biological role in BIF formation may not have been necessary.

Anthropocene: what (or who) is it for?

The made-up word chrononymy could be applied to the study of the names of geological divisions and their places on the International Stratigraphic Chart. Until 2008 that was something of a slow-burner, as careers go. It all began with Giovanni Arduino and Johann Gotlob Lehman in the mid- to late 18th century, during the informal historic episode known as the Enlightenment. To them we owe the first statements of stratigraphic principles and the beginning of stratigraphic divisions: rocks divided into the major segments of Primitive, Secondary, Tertiary and Quaternary (Arduino). Thus stratigraphy seeks to set up a fundamental scale or chart for expressing Earth’s history as revealed by rocks. The first two divisions bit the dust long ago; Tertiary is now an informal synonym for the Cenozoic Era; only Quaternary clings on as the embattled Period at the end of the Cenozoic.  All 11 Systems/Periods of the Phanerozoic, their 37 Series/Epochs and 85 Stages/Ages in the latest version of the International Stratigraphic Chart have been thrashed out since then, much being accomplished in the late 19th and early 20th centuries. Curiously, the world body responsible for sharpening up the definition of this system of ‘chrononymy’, the International Commission on Stratigraphy (ICS), seems not to have seen fit to record the history of stratigraphy: a great mystery. Without it geologists would be unable to converse with one another and the world at large.

Yet now an increasing number of scientists are seriously proposing a new entry at the 4th level of division after Eon, Era and Period: a new Epoch that acknowledges the huge global impact of human activity on atmosphere, hydrosphere, biosphere and even lithosphere. They want it to be called the Anthropocene, and for some its eventual acceptance ought to relegate the current Holocene Epoch, in which humans invented agriculture, a form of economic intercourse and exchange known as capital and all the trappings of modern industry, to the 5th division or Stage. Earth-pages has been muttering about the Anthropocene for the past decade, as charted in a number of the links above, so if you want to know which way its author is leaning and how he came to find the proposal an unnecessary irritation, have a look at them. Last week things became sufficiently serious for another comment. Simon Lewis and Mark Maslin of the Department of Geography at University College London have summarised the scientific grounds alleged to justify an Anthropocene Epoch and its strict definition in a Nature Perspective (Lewis, S.J. & Maslin, M.A. 2015. Defining the Anthropocene. Nature, v. 519, p. 171-180).-=, which is interestingly discussed in the same Issue by Richard Monastersky.

Lewis and Maslin present two dates that their arguments and accepted stratigraphic protocols suggest as candidates for the start of the Anthropocene: 1610 and 1964 CE, both of which relate to features that are expressed by geological records that should last indefinitely. The first is a decline and eventual recovery in the atmospheric CO2 level recorded in high-resolution Antarctic ice core records between 1570 and 1620 CE that can be ascribed to the decline in the population of the Americas’ native peoples from an estimated 60 to 6 million. This result of the impact of European first colonisation – disease, slaughter, enslavement and famine – reduced agriculture and fire use and saw the regeneration of 5 x 107 hectares of forest, which drew down CO2 globally. It also coincides with the coolest part of the Little Ice Age from 1594-1677 CE. They caution against the start of the Industrial Revolution as an alternative for a ‘Golden Spike’ since it was a diachronous event, beginning in Europe. Instead, they show that the second proposal for a start in 1964 has a good basis in the record of global anthropogenic effects on the Earth marked by the peak fallout of radioactive isotopes generated by atomic weapons tests during the Cold War, principally 14C with a 5730 year half life, together with others more long-lived. The year 1964 is also roughly when growth in all aspects of human activity really took off, which some dub in a slightly Tolkienesque manner the ‘Great Acceleration’. [There is a growing taste for this kind of hyperbole, e.g. the ‘Great Oxygenation Event’ around 2.4 Ga and the ‘Great Dying’ for the end-Permian mass extinction]. Yet they neglect to note that the geochronological origin point for times past has been defined as 1950 CE when nucleogenic 14C contaminated later materials as regards radiocarbon dating, which had just become feasible.   Lewis and Maslin conclude their Perspective as follows:

To a large extent the future of the only place where life is known to exist is being determined by the actions of humans. Yet, the power that humans wield is unlike any other force of nature, because it is reflexive and therefore can be used, withdrawn or modified. More widespread recognition that human actions are driving far-reaching changes to the life-supporting infrastructure of Earth may well have increasing philosophical, social, economic and political implications over the coming decades.

So the Anthropocene adds the future to the stratigraphic column, which seems more than slightly odd. As Richard Monastersky notes, it is in fact a political entity: part of some kind of agenda or manifesto; a sort of environmental agitprop from the ‘geos’. As if there were not dozens of rational reasons to change human impacts to haul society back from catastrophe, which many people outside the scientific community have good reason to see as  hot air on which there is never any concrete action by ‘the great and the good’. Monastersky also notes that the present Anthropocene record in naturally deposited geological materials accounts for less than a millimetre at the top of ocean-floor sediments. How long might the proposed Epoch last? If action to halt anthropogenic environmental change does eventually work, the Anthropocene will be  very short in historic terms let alone those which form the currency of geology. If it doesn’t, there will be nobody around able to document, let alone understand, the epochal events recorded in rocks. At its worst, for some alien, visiting planetary scientists, far in the future, an Anthropocene Epoch will almost certainly be far shorter than the 104 to 105 years represented by the hugely more important Palaeozoic-Mesozoic and Mesozoic-Cenozoic boundary sequences; but with no Wikipedia entry.

Not everybody gets a vote on these kinds of thing, such is the way that science is administered, but all is not lost. The final arbiter is the Executive Committee of the International Union of Geological Sciences (IUGS), but first the Anthropocene’s status as a new Epoch has to be approved by 60% of the ICS Subcommission on Quaternary Stratigraphy, if put to a vote. Then such a ‘supermajority’ would be needed from the chairs of all 16 of the ICS subcommissions that study Earth’s major time divisions. But first, the 37 members of the Subcommission on Quaternary Stratigraphy’s ‘Anthropocene’ working group have to decide whether or not to submit a proposal: things may drag on at an appropriately stratigraphic pace. Yet the real point is that the effect of human activity on Earth-system processes has been documented and discussed at length. I’ll give Marx the last word in this ‘The philosophers have only interpreted the world, in various ways. The point, however, is to change it’. A new stratigraphic Epoch doesn’t really seem to measure up to that…