Palaeoecology and biostratigraphy of early Cretaceous (Aptian) calcareous nannofossils and the δ13Ccarb isotope record from NE Iran

Mahanipour, Azam; Mutterlose, Jörg; Kani, Anoshiravan; Adabi, Mohammad Hossein

doi:10.1016/j.cretres.2011.01.006

Cited by 21 publications

(4 citation statements)

References 63 publications

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“…The disturbance in the carbon cycle related to OAE 1a is recorded in sedimentary successions worldwide, presenting a negative carbon-isotope anomaly at the onset of OAE 1a, followed by a positive excursion that extends into the late Aptian (e.g. Weissert, 1989;Weissert and Lini, 1991;Jenkyns, 1995;Menegatti et al, 1998;Bralower et al, 1999;Luciani et al, 2001;Bellanca et al, 2002;Price, 2003;van Breugel et al, 2007;Ando et al, 2008;Méhay et al, 2009;Malkoč et al, 2010;Mahanipour et al, 2011;Millán et al, 2009;Stein et al, 2011;Hu et al, 2012). Volcanism, associated with the emplacement C. Bottini et al: Aptian climate and ocean fertility of the Ontong Java Plateau (OJP), is thought to be the main triggering mechanism for global anoxia as well as for imposed greenhouse conditions (e.g.…”

Section: Introductionmentioning

confidence: 99%

Climate variability and ocean fertility during the Aptian Stage

et al. 2015

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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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Section: Introductionmentioning

confidence: 99%

Climate variability and ocean fertility during the Aptian Stage

et al. 2015

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“…The GTS also provides an integrated chart of biozonations, together with magnetostratigraphy. In addition, Mahanipour et al (2011, fig. 7) summarised Barremiane Aptian nannofossil zonations currently in use.…”

Section: Nannofossil Zonationmentioning

confidence: 99%

Integrated calcareous nannofossil and ammonite data from the upper Barremian–lower Albian of the northeastern Transdanubian Range (central Hungary): Stratigraphical implications and consequences for dating tectonic events

Szives

Fodor

Fogarasi

et al. 2018

Cretaceous Research

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The transition of post-obduction Neotethyan contraction to Eo-Alpine ("Austroalpine") nappe stacking that took place during the Early Cretaceous is an important event in the Cretaceous history of the Alpine-Carpathian-Dinaridic orogenic system. The Transdanubian Range (TR) in Hungary has been shown to have been impacted by both events. Dating of this transition has proved to be difficult; several interpretations were published during the last decades. Uniquely exposed in and around the Gerecse Mountains, the L abatlan Sandstone Formation (LSF) and the V ertessoml o Aleurolite Formation (VAF) bracket this time interval. The last phase of Neotethyan contraction occurred after the deposition of the LSF, and the Eo-Alpine nappe stacking started during the deposition of the VAF. Earlier stratigraphical studies provided valuable data for our understanding of geodynamics, but precise bio-and chronostratigraphy e to constrain the interval of deformations e became possible only with systematic correlation of macrofossil-poor outcrops to ammonite-rich series with the help of calcareous nannofossil data. Here new nannofossil data, and whenever still available, a re-examination of the original smear slides yields new constraints on the age of the younger part of the sequence. The nannofossil and ammonite record is now combined to create a local chronostratigraphical correlation, with records tied in to the integrated Tethyan nannofossil and ammonite biozonation, which, in turn, is numerically calibrated by international zonal standards and radiometric ages. Our study demonstrates that the youngest part of the sandstone-dominated LSF is in nannozone NC7B of late Aptian age. The overlying K€ osz€ or} uk} ob anya Conglomerate Member has a closely similar age in NC7A/B, noticeably older than previously suggested. On the other hand, the VAF clearly is of early Albian age (NC8). This latter unit is not represented in the inner Gerecse Mountains, in contrast to what has been suggested in previous studies. The observed earlier two sub-phases of Neotethyan compression with NeS to ENEeWSW shortening possibly are latest Aptian in age and are within nannofossil subzone NC7C, while the following Eo-Alpine deformation has an early Albian age (NC8) and is marked by WeE to NWeSE compression. The Aptian/Albian boundary (around 113 Ma) may indicate the switch of the TR from lower to upper position with respect to Neotethyan subduction to "Austroalpine" nappe stacking. Our data on deformational ages may support the idea that the onset of "Austroalpine" transpressional deformation at c. 114e112 myr ago could be related to the start of Penninic subduction, or, alternatively, to the onset of intra-oceanic subduction within the Austroalpine realm.

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“…The disturbance in the carbon cycle related to OAE 1a is recorded in sedimentary successions worldwide, presenting a negative carbon-isotope anomaly at the onset of OAE 1a, followed by a positive excursion that extends into the late Aptian (e.g. Weissert, 1989;Weissert and Lini, 1991;Jenkyns, 1995;Menegatti et al, 1998;Bralower et al, 1999;Erba et al, 1999;Luciani et al, 2001;Bellanca et al, 2002;Price, 2003;van Breugel et al, 2007;Ando et al, 2008;Méhay et al, 2009;Malkoč et al, 2010;Mahanipour et al, 2011;Millán et al, 2011;Stein et al, 2011;Hu et al, 2012). Volcanism, associated with the emplacement of the Ontong Java Plateau (OJP), is thought to be the main triggering mechanism for global anoxia as well as for imposed greenhouse conditions and ocean acidification during OAE 1a (e.g.…”

Section: Introductionmentioning

confidence: 99%

Climate variability and relationship with ocean fertility during the Aptian Stage

Bottini¹,

Erba²,

Tiraboschi³

et al. 2014

Preprint

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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.

show abstract

Palaeoecology and biostratigraphy of early Cretaceous (Aptian) calcareous nannofossils and the δ13Ccarb isotope record from NE Iran

Cited by 21 publications

References 63 publications

Climate variability and ocean fertility during the Aptian Stage

Climate variability and ocean fertility during the Aptian Stage

Integrated calcareous nannofossil and ammonite data from the upper Barremian–lower Albian of the northeastern Transdanubian Range (central Hungary): Stratigraphical implications and consequences for dating tectonic events

Climate variability and relationship with ocean fertility during the Aptian Stage

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