Dr. Haydon Mort

Universidade Federal de Pernambuco, Geologia, Faculty Member

Followers

Following

Co-authors

Public Views

British geoscientist.

Bachelor and Masters in Plymouth, Devon, UK
PhD, Neuchâtel, Switzerland
Post-doctoral researcher, Utrecht, The Netherlands

Currently visiting professor specialising in geochemistry and sedimentology. Main duties involve research, supervising bachelors and masters students, publishing papers in international peer-reviewed journals, obtaining external research funding.

Reviewer for the following journals: Nature Geosciences, Sedimentary Geology and Cretaceous Research.

Member of the European Geophysical Union, American Geophysical Union, American Geochemical Society, Geological Society of London

Consultant for the following charities: Sense About Science, British Science Association.

Other major interests: Philosophy and Religion.
Address: Department of Geology,
Federal University of Pernambuco,
Cidade Universitária,
50.740-530,
Recife – PE,
Brazil

less

InterestsView All (12)

Uploads

Papers by Dr. Haydon Mort

Palaeoenvironmental Constraints on Productivity at the Cenomanian-Turonian boundary: An Example from the Pueblo Stratotype, Colorado

by Alfonso Pardo, Dr. Haydon Mort, Zsolt A Berner, and Gerta Keller

Surface dwelling planktic foraminifera, H. planispira, register a +2.0 to 2.5 ppm delta13C excurs... more Surface dwelling planktic foraminifera, H. planispira, register a +2.0 to 2.5 ppm delta13C excursion straddling the Harland Shale and Bridge Creek Limestone member (latest Cenomanian) at the Pueblo Stratotype, Colorado. Post-excursion, the delta13C values remain at approximately 2.0 ppm dipping only slightly in the early Turonian (H. helvetica zone). During the initial phases of the delta13C excursion, 5 planktic species consecutively become extinct (Rotalipora deekei, R. greenhornensis, R. cushmani, P. inornata, G. bentonensis). These are subsequently replaced in the latter stages of the excursions by 5 new species with high depth tolerances, resulting in no net diversity loss. The extinction is therefore likely to have been as a direct result from the increased water mass stratification. A temporary decrease in bottom water productivity is also suggested by oxygenated bottom waters (presence of Cibidicoides) and a minimum of low O_2 tolerant species (hetrohelicids). Elevated HI/OH...

Download

Coupled Dynamics of Iron and Phosphorus in Sediments of an Oligotrophic Coastal Basin and the Impact of Anaerobic Oxidation of Methane

Plos One, Apr 23, 2013

Studies of phosphorus (P) dynamics in surface sediments of lakes and coastal seas typically empha... more Studies of phosphorus (P) dynamics in surface sediments of lakes and coastal seas typically emphasize the role of coupled iron (Fe), sulfur (S) and P cycling for sediment P burial and release. Here, we show that anaerobic oxidation of methane (AOM) also may impact sediment P cycling in such systems. Using porewater and sediment profiles for sites in an oligotrophic coastal basin (Bothnian Sea), we provide evidence for the formation of Fe-bound P (possibly vivianite; Fe 3 (PO 4 ) 2 . 8H 2 O) below the zone of AOM with sulfate. Here, dissolved Fe 2+ released from oxides is no longer scavenged by sulfide and high concentrations of both dissolved Fe 2+ (.1 mM) and PO 4 in the porewater allow supersaturation with respect to vivianite to be reached. Besides formation of Fe(II)-P, preservation of Fe-oxide bound P likely also contributes to permanent burial of P in Bothnian Sea sediments. Preliminary budget calculations suggest that the burial of Fe-bound P allows these sediments to act as a major sink for P from the adjacent eutrophic Baltic Proper.

Download

The expression of the Cenomanian–Turonian oceanic anoxic event in Tibet

Palaeogeography, Palaeoclimatology, Palaeoecology, 2013

The Gongzha section of Tibet, China is located at the northern margin of the Indian Plate (SE Tet... more The Gongzha section of Tibet, China is located at the northern margin of the Indian Plate (SE Tethys) and is characterized by hemipelagic grey marls and marly limestones, light grey limestones and silty limestones, but no organic-rich sediments. High-resolution biostratigraphy reveals an expanded Cenomanian–Turonian (CT) boundary interval and the δ13C record includes the main features of the classical positive carbon-isotope excursion that characterizes the CT oceanic anoxic event. The biotic response inferred from the foraminifera suggests that oxic to dysoxic conditions prevailed, except for a short interval marked by peak abundance of Heterohelix that indicates a significantly dysoxic environment during the δ13C “b” peak excursion. The overall decreasing trend in redox-sensitive trace elements (RSTE) during the maximum δ13C excursion confirms the absence of significant longer-lasting anoxia in the Gongzha section. Enrichments in RSTE are linked to phases of increased detrital input. Chemical weathering indices suggest that the upper Cenomanian sediments accumulated under an increasingly hot and humid climate that culminated near the CT boundary. In the early Turonian lower weathering indices suggest a warm, drier climatic regime with reduced continental runoff. Phosphorus mass-accumulation rates show a significant peak at the onset of the positive δ13C excursion, followed by a decrease up to the basal Turonian. This pattern is positively correlated with the long-term decrease in detrital index as also observed in numerous other CT boundary sections (e.g., Eastbourne, Pueblo, and Whadi El Ghaib, Sinaï). Long-term phosphorus accumulation in the Gongzha section is therefore associated with changes in detrital input. The overall decreased detrital input can be explained by the increasingly remote continental sources due to the major transgression at the end of Cenomanian, coupled with changes in continental weathering intensity linked to increasingly more arid climate conditions.

Download

Sulphate-sensitive seas

About 94.5 million years ago, oxygen levels in the deep ocean dropped while carbon burial rapidly... more

Download

Middle and late Cenomanian oceanic anoxic events in shallow and deeper shelf environments of western Morocco

The response of shallow-water sequences to oceanic anoxic event 2 and mid-Cenomanian events 1a an... more The response of shallow-water sequences to oceanic anoxic event 2 and mid-Cenomanian events 1a and 1b was investigated along the west African margin of Morocco north of Agadir (Azazoul) and correlated with the deep-water sequence of the Tarfaya Basin (Mohammed Beach) based on biostratigraphy, mineralogy, phosphorus and stable isotopes. In the deeper Mohammed Beach section results show double peaks in d13Corg for mid-Cenomanian events 1a and 1b (Rotalipora reicheli biozone, lower CC10a biozone), the characteristic oceanic anoxic event 2 d13C excursion (Rotalipora cushmani extinction, top of CC10a biozone) and laminated (anoxic) black shale. In the shallow environment north of Agadir, a ﬂuctuating sea-level associated with dysoxic, brackish and mesotrophic conditions prevailed during the middle to late Cenomanian, as indicated by oyster biostromes, nannofossils, planktonic and benthonic foraminiferal assemblages. Anoxic conditions characteristic of oceanic anoxic event 2 (for example, laminated black shales) did not reach into shallow-water environments until the maximum transgression of the early Turonian. Climate conditions decoupled along the western margin of Morocco between mid-Cenomanian event 1b and the Cenomanian–Turonian boundary, as also observed in eastern Tethys. North of Agadir alternating humid and dry seasonal conditions prevailed, whereas in the Tarfaya Basin the climate was dry and seasonal. This climatic decoupling can be attributed to variations in the Intertropical Convergence Zone and in the intensity of the north-east trade
winds in tropical areas.

Download

The biological origins of religious hyper-offense-taking: Implications for the new atheists discourse.

This article summarizes recent advancements regarding the neurology of offense-taking, and assess... more This article summarizes recent advancements regarding the neurology of offense-taking, and assesses how this understanding impacts the highly vocal war of ideas currently being fought between atheists and theists. The differences in approach to religious criticism within the current atheist movement are outlined by assessing the stance of four of the most prominent critics of religion; Richard Dawkins, Daniel C. Dennett, Sam Harris and Christopher Hitchens. The efficacy of each mode of criticism is discussed within a biological and social-psychological framework. A simple model is offered which demonstrates that blanket critiques of religion will very likely increase polarization, hostility and religious convictions within religious groups. Alternative approaches are offered which may enhance the acceptability of religious activities within society. The atheistic response to Islamic fundamentalism is briefly discussed.

Download

Phosphorus recycling and burial in Baltic Sea sediments with contrasting redox conditions

In this study, redox-dependent phosphorus (P) recycling and burial at 6 sites in the Baltic Sea i... more In this study, redox-dependent phosphorus (P) recycling and burial at 6 sites in the Baltic Sea is investigated using a combination of porewater and sediment analyses and sediment age dating (210Pb and 137Cs). We focus on sites in the Kattegat, Danish Straits and Baltic Proper where present-day bottom water redox conditions range from fully oxygenated and seasonally hypoxic to almost permanently anoxic and sulfidic. Strong surface enrichments of Fe-oxide bound P are observed at oxic and seasonally hypoxic sites but not in the anoxic basins. Reductive dissolution of Fe-oxides and release of the associated P supports higher sediment-water exchange of PO4 at hypoxic sites (up to 800 μmol P m-2 d-1) than in the anoxic basins. This confirms that Fe-bound P in surface sediments in the Baltic acts as a major internal source of P during seasonal hypoxia, as suggested previously from water column studies. Most burial of P takes place as organic P. We find no evidence for significant authigenic Ca-P formation or biogenic Ca-P burial. The lack of major inorganic P burial sinks makes the Baltic Sea very sensitive to the feedback loop between increased hypoxia, enhanced regeneration of P and increased primary productivity. Historical records of bottom water oxygen at two sites (Bornholm, Northern Gotland) show a decline over the past century and are accompanied by a rise in values for typical sediment proxies for anoxia (total sulfur, molybdenum and organic C/P ratios). While sediment reactive P concentrations in anoxic basins are equal to or higher than at oxic sites, burial rates of P at hypoxic and anoxic sites are up to 20 times lower because of lower sedimentation rates. Nevertheless, burial of reactive P in both hypoxic and anoxic areas is significant because of their large surface area and should be accounted for in budgets and models for the Baltic Sea.

Organic carbon deposition and phosphorus accumulation during Oceanic Anoxic Event 2 in Tarfaya, Morocco

With a multi-proxy approach, an attempt was made to constrain productivity and bottom-water redox... more With a multi-proxy approach, an attempt was made to constrain productivity and bottom-water redox conditions and their effects on the phosphorus accumulation rate at the Mohammed Plage section on the Tarfaya coast, Morocco, during the Cenomanian-Turonian Anoxic Event (OAE 2). A distinct δ13Corg isotope excursion of +2.5‰ occurs close to the top of the section. The unusually abrupt shift of the isotope excursion and disappearance of several planktonic foraminiferal species (e.g. Rotalipora cushmani and Rotalipora greenhornensis) in this level suggests a hiatus of between 40–60 kyrs at the excursion onset. Nevertheless, it was possible to determine both the long-term environmental history as well as the processes that took place immediately prior to and during OAE 2. TOC% values increase gradually from the base of the section to the top (from 2.5% to 10%). This is interpreted as the consequence of a long-term eustatic sea-level rise and subsidence causing the encroachment of less oxic waters into the Tarfaya Basin. Similarly a reduction in the mineralogically constructed ‘detrital index’ can be explained by the decrease in the continental flux of terrigenous material due to a relative sea-level rise. A speciation of phosphorus in the upper part of the section, which spans the start and mid-stages of OAE 2, shows overall higher abundances of Preactive mass accumulation rates before the isotope excursion onset and lower values during the plateau. Due to the probable short hiatus, the onset of the decrease in phosphorus content relative to the isotope excursion is uncertain, although the excursion plateau already contains lower concentrations. The Corg/Ptotal and V/Al ratios suggest that this reduction was mostly likely caused by a decrease in the available bottom oxygen content (probably as a result of higher productivity) and a corresponding fall in the phosphorus retention ability of the sediment. Productivity appears to have remained high during the isotope plateau possibly due to a combination of ocean-surface fertilisation via increased aridity (increased K/Al and Ti/Al ratios) and/or higher dissolved inorganic phosphorus content in the water column as a result of the decrease in sediment P retention. The evidence for decreased P-burial has been observed in many other palaeoenvironments during OAE 2. Tarfaya's unique upwelling paleosituation provides strong evidence that the nutrient recycling was a global phenomenon and therefore a critical factor in starting and sustaining OAE 2.

Phosphorus and the roles of productivity and nutrient recycling during oceanic anoxic event 2

Four sections documenting the impact of the late Cenomanian oceanic anoxic event (OAE 2) were stu... more Four sections documenting the impact of the late Cenomanian oceanic anoxic event (OAE 2) were studied in basins with different paleoenvironmental regimes. Accumulation rates of phosphorus (P) bound to iron, organic matter, and authigenic phosphate are shown to rise and arrive at a distinct maximum at the onset of OAE 2, with an associated increase in δ13C values. Accumulation rates of P return to pre-excursion values in the interval where the δ13C record reaches its first maximum. An offset in time between the maximum in P accumulation and peaks in organic carbon burial, hydrogen indices, and Corg/Preact molar ratios is explained by the evolution of OAE 2 in the following steps. (1) An increase in productivity increased the flux of organic matter and P into the sediments; the preservation of organic matter was low and its oxidation released P, which was predominantly mineralized. (2) Enhanced productivity and oxidation of organic matter created dysoxic bottom waters; the preservation potential for organic matter increased, whereas the sediment retention potential for P decreased. (3) The latter effect sustained high primary productivity, which led to an increase in the abundance of free oxygen in the ocean and atmosphere system. After the sequestration of CO2 in the form of black shales, this oxygen helped push the ocean back into equilibrium, terminating black shale deposition and removing bioavailable P from the water column.

The Cenomanian/Turonian anoxic event at the Bonarelli Level in Italy and Spain: enhanced productivity and/or better preservation?

The upper Cenomanian pelagic sediments of Furlo in the northern Apennines, Italy, are characteriz... more The upper Cenomanian pelagic sediments of Furlo in the northern Apennines, Italy, are characterized by a 1.5-m-thick organic-rich stratigraphic horizon called the Bonarelli Level, which represents the second major oceanic anoxic event in the Cretaceous (OAE 2). The Bonarelli Level is depleted in carbonates and consists essentially of biogenic quartz, phyllosilicates, and organic matter, with values of TOC reaching 18%. The age of the Furlo section is constrained by correlating its δ13C curve with that of the well-dated Pueblo (USA) and Eastbourne (UK) sections. The presence of all the planktonic foraminiferid zones and details of the OAE 2 δ13C excursion indicates a relatively continuous but reduced sedimentation rate across the Cenomanian/Turonian (C/T) boundary. Sediment and TOC mass accumulation rates have been calculated and suggest a sedimentation break in the upper Bonarelli Level. This may be an artifact of the diachronous FAD of the planktonic foraminiferid Helvetoglobotruncana helvetica and suggests that in some sections the δ13C curve may provide more reliable age control for dating the C/T boundary. In order quantitatively to explain the carbon isotope curve and the measured TOC mass accumulation rate, a simple dynamic model of the isotope effects of organic versus inorganic carbon burial was developed. In order to verify the consistency of the model we correlated the modeled output of the Furlo section with that of the Manilva section, in southeast Spain. The modeling shows that increasing productivity only partially explains the measured δ13C excursion and is not the only factor relevant to black shales deposition. Preservation may play a central role, especially in the later stages of OAE 2. Phosphorus and TOC accumulation patterns in the Bonarelli Level in both Furlo and Manilva suggest a similar process although other factors may also be involved.

Talks by Dr. Haydon Mort

What do black shales and red beds have in common?

So-called Cretaceous Oceanic Red Beds (CORBs) frequently follow periods of black shale deposition... more So-called Cretaceous Oceanic Red Beds (CORBs) frequently follow periods of black shale deposition. This, in turn, has led to some suggestions that the two are somehow causally related. This presentation is a speculative look at the geochemical pathways that may connect CORBs and black shales and what may cause one to lead to the other.

Drawing on a geochemical study focusing on OAE 2, we are able to construct a plausible mechanism that causally links these phenomena given the similarities between the phosphorus and iron (Fe) cycles. Phosphorus mass accumulation rates (P MARs) in Tethyan and Western Interior realms peak at the onset OAE 2’s δ13 C positive isotope excursion. This is possibly due to the mechanical reworking of continental margins during a period of maximum sea-level transgression. A subsequent decrease in P MARs before the isotope plateau was probably caused by 1) capping of drowned sediments and 2) decreased oxygen availability in pore waters reducing the ability of the sediments to retain phosphorus.

If we assume that bottom oxygen levels were the primary control on P burial, it would be logical to predict an increase in P MARs at the end of OAE 2. We present evidence for this in an Egyptian section. Although more sections need to be analyzed we can conﬁdently say that, given the redox links between P and Fe, the Fe cycle should behave in a similar way. If Fe accumulation increases after OAE 2, it is likely to be for the same reason(s) that drove the increase in P. Therefore the formation of black shales and red beds can be seen as a series of redox thresholds where P and Fe are in dynamic equilibrium with oceanic and atmospheric O2 content.

A second aspect of this presentation illustrates how red bed formation maybe diachronous, even if they were caused by the same event. The gradual extinction of certain species of planktonic foraminifera clearly shows that the expansion of the oxygen minimum zone, during OAE 2, was not geologically instantaneous (i.e. it occurred over some 10’s of ka). If Fe is controlled by bottom water O2 content then it is possible that the stepwise expansion and contraction of the OMZ affected environments at different times. This may explain why differences in the age estimates for the onset of CORB deposition occur. Conﬂicting ages could be reconciled with a deeper appreciation of how a sections paleodepth affects the timing of geochemical porewater changes.

Bridging the gap between science and sprirituality

A short presentation given to a Christian youth group in Bern, Switzerland. The talk covers a gen... more

Biogeochemical Changes During OAE 2: A Multisite Phosphorus Speciation

Understanding the sources and behaviour of productivity limiting nutrients, such as phosphorus, i... more Understanding the sources and behaviour of productivity limiting nutrients, such as phosphorus, is critical in our understanding the triggers and development of past climate changes. We present results from a sequential extraction of phosphorus from four sections that differ in their paleoenvironmental situation during oceanic anoxic event 2, (93.5 Ma). The sections are Pueblo (Colorado), Furlo (Italy), Manilva (Spain) and Eastbourne (UK). Mass accumulation rate corrections have been applied in all cases is give P MARs. We also integrate kaolinite and rock-eval data, collected from Pueblo, into our disussion.
We observe a significant peak in all P MARs. The must abundant of these is authigenic in origin. However the first δ13C peak is offset from the P MAR peaks by some tens of thousands of years. P MARs tend to rise, initially in step with δ13C values but then decrease to pre-excursion values at or just after the first isotope peak. This behaviour is indicative of phosphorus recycling under increasingly anoxic conditions. The regeneration of phosphorus may have sustained productivity beyond that which would have been possible by continental nutrient influx alone. Kaolinite clearly spikes at the base of the isotope excursion in Pueblo, suggesting a brief period of humidity preceded isotope excursion. Rock-eval shows a rapid sea-level transgression at the δ13C excursion, which could have reworked the kaolinite and/or remobilised nutrients. The abundance of shallow seas during this period make it possible that one or both of these factors was responsible for supplying the initial nutrient levels to boost productivity. However if productivity was responsible for the characteristic isotope plateaux during OAE 2, then it is unlikely that nutrients alone were directly responsible. The decline in P MAR, as an expression of recycling under anoxia, is an appealing explanation for sustained productivity.
These results give valuable insights into the causal mechanism of OAE 2 and offer new avenues of investigation into the other OAEs that occurred periodically during the mid-late Cretaceous.

Dr. Haydon Mort

Uploads

Papers by Dr. Haydon Mort

Talks by Dr. Haydon Mort

Log In