Climate variability and relationship with ocean fertility during the Aptian Stage

Abstract. Several studies have been conducted to reconstruct temperature variations across the Aptian Stage, particularly during the Early Aptian Oceanic Anoxic Event (OAE)1a. There is a general consensus that a major warming characterized the OAE 1a, although some studies have provided evidence for transient "cold snaps" or cooler intervals during the event. The climatic conditions for the middle–late Aptian are less constrained, and a complete record through the Aptian is not available. Here we present a reconstruction of surface-water palaeotemperature and fertility based on calcareous nannofossil records from the Cismon and Piobbico cores (Tethys) and DSDP Site 463 (Pacific Ocean). The data, integrated with oxygen-isotope and TEX86 records, provide a detailed picture of climatic and ocean fertility changes during the Aptian Stage, which are discussed in relation to the direct/indirect role of volcanism. Warm temperatures characterized the pre-OAE 1a interval followed by a maximum warming (of ~2–3 °C) during the early phase of anoxia under intense volcanic activity of the Ontong Java Plateau (OJP). A short-lived (~35 ky) cooling episode interrupted the major warming, following a rapid increase of weathering rates. Nannofossils indicate that eutrophic conditions were reached when temperatures were at their highest and OJP volcanism most intense, thus suggesting that continental runoff, together with increased input of hydrothermal metals, increased nutrient supply to the oceans. The latter part of OAE 1a was characterized by cooling events, probably promoted by CO2 sequestration during burial of organic matter. In this phase, high productivity was probably maintained by N2-fixing cyanobacteria while nannofossil taxa indicating high fertility were rare. The end of anoxia coincided with the cessation of volcanism and a pronounced cooling. The mid-Aptian was characterized by high surface-water fertility and progressively decreasing temperatures, probably resulting from intense continental weathering drawing down pCO2. The lowest temperatures, combined with low fertility, were reached in the middle–late Aptian across the interval characterized by blooming of Nannoconus truittii. The data presented suggest that OJP activity played a direct role in inducing global warming during the early Aptian, whereas other mechanisms (weathering, deposition of organic matter) acted as feedback processes, favouring temporary cooler interludes.

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Climate variability and ocean fertility during the Aptian Stage

Climate of the Past ◽

10.5194/cp-11-383-2015 ◽

2015 ◽

Vol 11 (3) ◽

pp. 383-402 ◽

Cited By ~ 52

Author(s):

C. Bottini ◽

E. Erba ◽

D. Tiraboschi ◽

H. C. Jenkyns ◽

S. Schouten ◽

...

Keyword(s):

Organic Matter ◽

Surface Water ◽

Climatic Conditions ◽

Low Fertility ◽

Ontong Java Plateau ◽

Direct Role ◽

High Productivity ◽

Oceanic Anoxic Event ◽

Continental Runoff ◽

Maximum Warming

Abstract. Several studies have been conducted to reconstruct temperature variations across the Aptian Stage, particularly during early Aptian Oceanic Anoxic Event (OAE) 1a. There is a general consensus that a major warming characterized OAE 1a, although some studies have provided evidence for transient "cold snaps" or cooler intervals during the event. The climatic conditions for the middle–late Aptian are less constrained, and a complete record through the Aptian is not available. Here we present a reconstruction of surface-water palaeotemperature and fertility based on calcareous nannofossil records from the Cismon and Piobbico cores (Tethys) and DSDP Site 463 (Pacific Ocean). The data, integrated with oxygen-isotope and TEX86 records, provide a detailed picture of climatic and ocean fertility changes during the Aptian Stage, which are discussed in relation to the direct/indirect role of volcanism. Warm temperatures characterized the pre-OAE 1a interval, followed by a maximum warming (of ~ 1.5–2 °C) during the early phase of anoxia under intense volcanic activity of the Ontong Java Plateau (OJP). A short-lived cooling episode interrupted the major warming, following a rapid increase in weathering rates. Nannofossils indicate that mesotrophic conditions were reached when temperatures were at their highest and OJP volcanism most intense, thus suggesting that continental runoff, together with increased input of hydrothermal metals, increased nutrient supply to the oceans. The latter part of OAE 1a was characterized by cooling events, probably promoted by CO2 sequestration during burial of organic matter. In this phase, high productivity was probably maintained by N2-fixing cyanobacteria, while nannofossil taxa indicating higher fertility were rare. The end of anoxia coincided with the cessation of volcanism and a pronounced cooling. The mid-Aptian was characterized by highest surface-water fertility and progressively decreasing temperatures, probably resulting from intense continental weathering drawing down pCO2. The lowest temperatures, combined with low fertility, were reached in the middle–late Aptian across the interval characterized by blooming of Nannoconus truittii. The prolonged cooling was followed by significant warming across the Aptian–Albian boundary. The data presented suggest that OJP activity played a direct role in inducing global warming during the early Aptian, whereas other mechanisms (weathering, deposition of organic matter) acted as feedback processes, favouring temporary cooler interludes.

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Monsoon variability during Mid Pliocene Warm Period: Evidence from oceanic denitrification at eastern Arabian Sea

10.5194/egusphere-egu21-12089 ◽

2021 ◽

Author(s):

Padmasini Behera ◽

Manish Tiwari

Keyword(s):

Organic Matter ◽

Surface Water ◽

Water Column ◽

Arabian Sea ◽

Water Productivity ◽

Warm Period ◽

Late Pliocene ◽

High Productivity ◽

Future Global Warming ◽

Eastern Arabian Sea

The variability of the South Asian Monsoon (SoAM) in warmer climatic conditions is not established yet. The Mid-Pliocene Warm Period (MPWP, 3.264 to 3.025 ma) is the most recent such event when the boundary conditions were similar to present with similar CO2 concentration (more than 400 ppmv) and temperature (2-3&#176;C higher than present). It presents the best analogue for understanding the impacts of future global warming on SoAM. The high-resolution study of denitrification from the eastern Arabian Sea can provide an insight into the SoAM variability during MPWP. Denitrification is the process by which nitrate is reduced to nitrogen gas (N2 or N2O) during organic matter decay in oxygen minima zones in the water column. The denitrification process enriches the nitrate pool with 15N, which is incorporated in the particulate organic matter. Denitrification is governed by the surface water productivity related to SoAM strength and the water column ventilation. We analyzed the nitrogen isotopic ratio of sedimentary organic matter (SOM, &#948;15NSOM) to examine the denitrification in the eastern Arabian Sea. Total nitrogen (TN %) and total organic carbon (TOC%) are used to estimate the surface water productivity from the sediment collected during expedition IODP 355, Hole U1456A. We find that the &#948;15NSOM values vary between 7-9 &#8240; during 3.22-3.15 Ma and 2.9-2.75 Ma indicating high denitrification. High &#948;15NSOM values coincide with high productivity as shown by both TN and TOC. It shows two major periods in the late Pliocene (3.22-3.15 Ma and 2.92-2.75 Ma) associated with stronger denitrification and high productivity. These results indicate the intensification of SoAM during warmer periods of Late Pliocene and at the start of intensification of Northern hemisphere glaciation. The enhanced denitrification during this period could possibly be due to a reduction in deep water ventilation and monsoon driven upsurge in productivity.

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Mid-Cretaceous paleoenvironmental changes in the western Tethys

Climate of the Past ◽

10.5194/cp-14-1147-2018 ◽

2018 ◽

Vol 14 (8) ◽

pp. 1147-1163 ◽

Cited By ~ 14

Author(s):

Cinzia Bottini ◽

Elisabetta Erba

Keyword(s):

Surface Water ◽

Cold Water ◽

Global Scale ◽

Climatic Conditions ◽

Black Shales ◽

Temperature Index ◽

Western Tethys ◽

Oceanic Anoxic Event ◽

Cooling Trend

Abstract. We present a continuous record of surface water temperature and fertility variations through the latest Barremian–Cenomanian interval (ca. 27 Myr) based on calcareous nannofossil abundances from the western Tethys. The nannofossil temperature index, calibrated with TEX86 sea surface temperatures, suggests that warmest (34–36 ∘C) conditions were reached during oceanic anoxic event (OAE) 1a onset, the Aptian–Albian boundary interval hyperthermals (113, Kilian level and Urbino level OAE 1b) and during a ca. 4 Myr long phase in the middle Albian. Coolest temperatures (29 ∘C) correspond instead to the late Aptian. Generally warm conditions characterized the Albian followed by a progressive cooling trend that started in the latest Albian (at the Marne a Fucoidi–Scaglia Bianca Formation transition). Temperate conditions occurred in the Cenomanian with frequent short-term variations highlighted by abundance peaks of the cold-water nannofossil species E. floralis and R. parvidentatum. Mid-Cretaceous surface water fertility was rather fluctuating and mostly independent from climatic conditions as well as from black shales intervals. Intense warming and fertility spikes were systematically associated only with black shales of OAE 1a and of the Aptian–Albian boundary hyperthermals. The Albian–Cenomanian rhythmic black shales are, in fact, associated with varying long-term climatic and fertility conditions. The similarity of western Tethys climatic and fertility fluctuations during OAE 1a, OAE 1b, the middle Albian and OAE 1d with nannofossil-based records from other basins indicated that these paleoenvironmental conditions were affecting the oceans at supra-regional to global scale.

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Carbon Isotopic Signature and Organic Matter Composition of Cenomanian High-Latitude Paleosols of Southern Patagonia

Geosciences ◽

10.3390/geosciences11090378 ◽

2021 ◽

Vol 11 (9) ◽

pp. 378

Author(s):

Augusto Nicolás Varela ◽

María Sol Raigemborn ◽

Patricio Emmanuel Santamarina ◽

Sabrina Lizzoli ◽

Thierry Adatte ◽

...

Keyword(s):

Organic Matter ◽

Carbon Isotope ◽

Southern Hemisphere ◽

Isotopic Signature ◽

Climatic Conditions ◽

Organic Carbon Content ◽

Oceanic Anoxic Event ◽

Palynological Data ◽

Stable Pattern ◽

Southern Patagonia

The Cenomanian Mata Amarilla Formation (MAF) in southern Patagonia (~55° S paleolatitude, Austral-Magallanes Basin, Argentina) is composed mainly of stacked fluvial deposits with intercalated paleosols, which document Cenomanian environments at high-paleolatitudes in the Southern Hemisphere. We performed a multiproxy study of the paleosols and sediments of the MAF in order to (1) understand the composition of the soil- and sediment-derived organic matter (OM), (2) apply carbon isotope stratigraphy as a tool to correlate patterns obtained from the MAF with existing marine and non-marine δ13Corg records worldwide, and (3) investigate the relationship between variations in spore-pollen assemblages of the MAF and the climatic conditions prevailing in the Cenomanian Southern Hemisphere. An integrated dataset was generated, including total organic carbon content, Rock-Eval pyrolysis data, stable isotope (δ13Corg) composition, and palynological data, combined with published paleosol-derived mean annual temperatures and mean annual precipitations. The results indicated that the OM preserved in the MAF paleosols allowed its use as a chemostratigraphic tool. The MAF δ13Corg curve showed the rather stable pattern characteristic for the Early to Late Cenomanian interval. The absence of the major positive carbon isotope excursion associated with oceanic anoxic event 2 provided an upper limit for the stratigraphic range of the MAF. The palynological data suggested the development of fern prairies during warmer and moister periods at the expense of the background gymnosperm-dominated forests. Overall, the multiproxy record provided new insights into the long-term environmental conditions during the Cenomanian in the high latitudes of the Southern Hemisphere.

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Assessing controls on organic matter enrichments in hemipelagic homogenous marls of the Cretaceous Vocontian Basin (France): an unexpected variability observed from multiple organic-rich levels

BSGF - Earth Sciences Bulletin ◽

10.1051/bsgf/2022001 ◽

2022 ◽

Author(s):

Alexis Caillaud ◽

Melesio Quijada ◽

Stephan R. Hlohowskyj ◽

Anthony Chappaz ◽

Viviane Bout-Roumazeilles ◽

...

Keyword(s):

Organic Matter ◽

Surface Water ◽

Sea Level ◽

Water Productivity ◽

The Other ◽

Redox Conditions ◽

Accumulation Rates ◽

High Productivity ◽

Anoxic Events ◽

Parameter Approach

The Marnes Bleues Formation from the Vocontian Basin (Southeastern France) shows many organic rich levels, some concomitant to oceanic anoxic events OAE1a and OAE1b. These organic-rich levels are scattered through a thick homogeneous succession of marls, poor in organic matter (OM). Through a multi-parameter approach, the organic-rich levels from the Aptian-Albian were characterized. Our results show that all OM-rich levels exhibit variable characteristics, such as OM nature (marine vs. continental), sedimentation and accumulation rates, redox conditions, surface-water productivity and relative sea level, but they all show low to modest enrichments in OM. Furthermore, all the levels share in common the fact that they formed under conditions of normal to low productivity and oxic to suboxic conditions. Thus, our results strongly suggest that, in the absence of high productivity and anoxic bottom conditions, the other factors reputed to favor OM accumulation only led to sporadic and low enrichments in organic contents. It is as if such factors could only enhance OM accumulation but could not induce it alone. What was true for the Vocontian Basin may be extended to other settings, regardless of their time of deposition or location.

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Mid-Cretaceous paleoenvironmental changes in the western Tethys

10.5194/cp-2018-34 ◽

2018 ◽

Author(s):

Cinzia Bottini ◽

Elisabetta Erba

Keyword(s):

Surface Water ◽

Cold Water ◽

Global Scale ◽

Climatic Conditions ◽

Black Shales ◽

Temperature Index ◽

Western Tethys ◽

Oceanic Anoxic Event ◽

Cooling Trend

Abstract. We present a continuous record of surface water temperature and fertility variations through the latest Barremian–Cenomanian interval (ca. 27 My) based on calcareous nannofossil abundances from the western Tethys. The nannofossil temperature index, calibrated with TEX86-Sea Surface Temperatures, suggests that warmest (34–36 °C) conditions were reached during Oceanic Anoxic Event (OAE) 1a onset, the Aptian/Albian boundary interval hyperthermals (113, Kilian Level and Urbino Level-OAE 1b), and during a ca. 4 My-long phase in the middle Albian. Coolest temperatures (29 °C) correspond, instead, to the late Aptian. Generally warm conditions characterized the Albian followed by a progressive cooling trend started in the latest Albian (at the Marne a Fucoidi/Scaglia Bianca Formation transition). Temperate conditions occurred in the Cenomanian with frequent short-term variations highlighted by abundance peaks of cold-water nannofossil species E. floralis and R. parvidentatum. Mid-Cretaceous surface water fertility was rather fluctuating and mostly independent from climatic conditions as well as from black shales intervals. Intense warming and fertility spikes resulted to be systematically associated only to black shales of OAE 1a and of the Aptian/Albian boundary hyperthermals. The Albian–Cenomanian rhythmic black shales are, in fact, associated with varying long-term climatic/fertility conditions. The similarity of western Tethys climatic/fertility fluctuations during OAE 1a, OAE 1b, the middle Albian and OAE 1d with nannofossil-based records from other basins indicated that these paleoenvironmental conditions were affecting the oceans at supra-regional to global scale.

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ON-FARM FORESTRY DEVELOPMENT OPTIONS FOR NORTHLAND

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.1986.47.1762 ◽

1986 ◽

pp. 27-32

Author(s):

J.S. Clark

Keyword(s):

Joint Ventures ◽

Low Fertility ◽

High Fertility ◽

Financial Returns ◽

Farm Forestry ◽

Hill Country ◽

Financial Position ◽

On Farm

Agroforests and woodlots offer Northland hill country farmers investment and diversification opportunities. Agroforests have less effect on the "whole farm" financial position than woodlots, especially where a progressive planting regime is adopted and where no further borrowing is required. Establishment and tending costs for agro-forests are lower, and returns come much sooner. The proven opportunity for continued grazing under trees established in this manner, apart from a short post-planting period, further enhances the agroforesty option. Even where there is reluctance on a farmer's part to plant trees on high fertility land, the expected financial returns from agroforests on low and medium fertility land will increase the overall long-term profitability and flexibility of the whole farming operation. Woodlots may be more appropriate on low fertility areas where weed reversion is likely. Joint ventures may be worth considering where farm finances are a limited factor. Keywords: On-farm forestry development, Northland hill country, agroforestry, woodlots, diversification, joint ventures, progressive planting regimes, grazing availability.

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Characterisation of production of organic rich topsoil from sludge

Water Science & Technology ◽

10.2166/wst.2000.0205 ◽

2000 ◽

Vol 42 (9) ◽

pp. 195-201 ◽

Cited By ~ 1

Author(s):

P. Andreasen ◽

P. B. Mortensen ◽

A. Stubsgaard ◽

B. Langdahl

Keyword(s):

Organic Matter ◽

Oxygen Consumption ◽

Oxygen Transport ◽

Mineral Soil ◽

Climatic Conditions ◽

Growth Media ◽

Soil Mixture ◽

Water Suspension ◽

Aerobic Process ◽

Stable Product

The stabilisation of a sludge-mineral soil mixture and a method to evaluate the state of stabilisation were investigated. The organic matter and nitrogen content are reduced up to 50% during a stabilisation process of three months under Danish climatic conditions. The stabilisation was shown to be an aerobic process limited by oxygen transport within the mixture. The degree of stabilisation was evaluated by oxygen consumption in a water suspension and the results showed that a stable product was achieved when oxygen consumption was stable and in the level of natural occurring aerobic soils (0.1 mgO2/(g DS*hr). The study thereby demonstrates that a stability of a growth media can be controlled by the oxygen consumption method tested.

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EVALUATING ORGANIC MATTER SULFURIZATION AS A MECHANISM OF ENHANCED BURIAL OF REDUCED CARBON AND SULFUR ACROSS THE TOARCIAN OCEANIC ANOXIC EVENT

10.1130/abs/2019se-327732 ◽

2019 ◽

Author(s):

Selva M. Marroquín ◽

◽

Jordan Alexandria Pritchard ◽

Karl B. Föllmi ◽

Alicia Fantasia ◽

...

Keyword(s):

Organic Matter ◽

Oceanic Anoxic Event ◽

Anoxic Event

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Effect of Digestate and Straw Combined Application on Maintaining Rice Production and Paddy Environment

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18115714 ◽

2021 ◽

Vol 18 (11) ◽

pp. 5714

Author(s):

Xue Hu ◽

Hongyi Liu ◽

Chengyu Xu ◽

Xiaomin Huang ◽

Min Jiang ◽

...

Keyword(s):

Organic Matter ◽

Surface Water ◽

Soil Organic Matter ◽

Paddy Soil ◽

Rice Yield ◽

Soil Surface ◽

Rice Production ◽

Straw Decomposition ◽

Rice Grains ◽

Combined Application

Few studies have focused on the combined application of digestate and straw and its feasibility in rice production. Therefore, we conducted a two-year field experiment, including six treatments: without nutrients and straw (Control), digestate (D), digestate + fertilizer (DF), digestate + straw (DS), digestate + fertilizer + straw (DFS) and conventional fertilizer + straw (CS), to clarify the responses of rice growth and paddy soil nutrients to different straw and fertilizer combinations. Our results showed that digestate and straw combined application (i.e., treatment DFS) increased rice yield by 2.71 t ha−1 compared with the Control, and digestate combined with straw addition could distribute more nitrogen (N) to rice grains. Our results also showed that the straw decomposition rate at 0 cm depth under DS was 5% to 102% higher than that under CS. Activities of catalase, urease, sucrase and phosphatase at maturity under DS were all higher than that under both Control and CS. In addition, soil organic matter (SOM) and total nitrogen (TN) under DS and DFS were 20~26% and 11~12% higher than that under B and DF respectively, suggesting straw addition could benefit paddy soil quality. Moreover, coupling straw and digestate would contribute to decrease the N content in soil surface water. Overall, our results demonstrated that digestate and straw combined application could maintain rice production and have potential positive paddy environmental effects.

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