Magnetic methods and the timing of geological processes

Jovane, Luigi; Hinnov, Linda A.; Housen, Bernard A.; Herrero-Barvera, E.

doi:10.1144/sp373.17

Cited by 12 publications

(6 citation statements)

References 130 publications

(103 reference statements)

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“…U‐channel ARM and IRM data were processed and deconvolved with the software of Xuan and Channell (). Parameters were calculated as follows: (i) S ratio (as IRM@‐0.3/IRM@1) and (ii) Hard IRM (HIRM) (as [IRM@‐0.3+IRM@1]/2) (Jovane et al, ; Liu et at., ; Verosub & Roberts, ).…”

Section: Methodsmentioning

confidence: 99%

Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil

et al. 2019

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Magnetotactic bacteria (MTB) synthesize magnetite and greigite crystals under low oxygen conditions in the water column or uppermost sediment (greigite‐producing bacteria are found below the oxic‐anoxic transition). Dissolved iron and oxygen contents in local environments are known to be limiting factors for the production and preservation of biogenic magnetite. Understanding the processes that link MTB to their living environments is fundamental to reconstructing past chemical variations in the water column and sediment, and for using the magnetic properties of biogenic magnetite as environmental proxy indicators. Previous studies have suggested that the frequently identified biogenic soft (BS) and biogenic hard (BH) magnetite types are associated with equant and more elongated morphologies, respectively, and that their abundance varies in accordance with sedimentary oxygen content, where MTB that produce the BH component live in less oxygenated environments. We test this hypothesis in a high‐resolution integrated environmental magnetic and geochemical study of surface sediments from Mamanguá Ría, SE Brazil. Based on magnetic and pore water profiles, we demonstrate that both the BS and BH components occur within microaerobic environments and that as sediment oxygen content decreases with depth, the BS component disappears before the BH component. With continued burial into the sulfidic diagenetic zone, both components undergo progressive dissolution, but the BH component is more resistant to dissolution than the BS component. Our observations confirm previous inferences about the relative stability of these phases and provide a firmer basis for use of these two types of biogenic magnetite as paleoenvironmental proxies.

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Section: Methodsmentioning

confidence: 99%

Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil

et al. 2019

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“…χ includes contributions from all minerals (diamagnetic, paramagnetic and ferrimagnetic) present in the sediment in proportion to their abundance. Usually in the Tethyan Realm, it is a direct function of the terrigenous input into the basin (Jovane et al, 2004(Jovane et al, , 2013Roberts et al, 2013).…”

Section: Magnetic Susceptibility and Gamma-ray Logsmentioning

confidence: 99%

Multistratigraphic records of the Lower Cretaceous (Valanginian–Cenomanian) Puez key area in N. Italy

Lukeneder

Soták

Jovane

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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We present a stratigraphic investigation of a Hauterivian to Cenomanian hemipelagic succession from Col Puez, in the Dolomites (Southern Alps, northern Italy). A composite section of seven segments was studied with bio-, magneto-, and chemostratigraphy, which enabled detailed and robust age calibration of the Puez succession. It also revealed the paleoceanographic history and helped identify the important global climatic events of that period. The age of the Lower Cretaceous Puez Formation in the Dolomites is refined as late Hauterivian to early Cenomanian. Ammonoids provide a detailed biostratigraphic subdivision that forms the basis for analyses of the faunal distribution and the paleoenvironmental evolution of basins and plateaus across the Tethys. The succession consists of facies similar to those of coeval units in the Tethys, apart from the late Barremian to late Aptian interval, which is marked by a major hiatus followed by a few-metersthick redbed of late Aptian age. The Lower Cretaceous was characterized by a weak (~1‰) positive δ 13 C trend, punctuated by a positive shift in the late Hauterivian corresponding to the Faraoni Level. Oxygen isotope values show a decreasing trend from the Hauterivian to the Albian/Cenomanian, which mirrors a long-term increasing trend in paleotemperatures from ~15-18°C to ~25-30°C. This is in agreement with global paleotemperature reconstructions for this period representing the onset of mid-Cretaceous super-greenhouse conditions. Nonetheless, no black shale occurs at the intervals equivalent to Aptian-Albian oceanic anoxic events (OAE), suggesting unique paleoceanographic conditions (enhanced current activity on a submarine height) on the Trento Plateau area during the mid-Cretaceous.

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“…Artificial magnetic fields of known characteristics were used in order to study the response of the samples in different conditions and the following parameters were determined: (a) anhysteretic remanent magnetization (ARM), which was measured first by imposing a 0.1 mT DC bias field while applying a 0.1 T demagnetizing alternating field, and then by progressively demagnetizing via AF with fields of 50, 100, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1,000 mT; (b) backfield isothermal remanent magnetization (BIRM), was imparted by applying first a 1.0T direct field (IRM@1.0) and subsequently by applying a 0.1 (IRM@-0.1) and 0.3 mT (IRM@-0.3) direct field in the opposite direction (e.g., King and Channell, 1991;Verosub and Roberts, 1995;Liu et al, 2012;Jovane et al, 2013).…”

Section: Environmental Magnetismmentioning

confidence: 99%

Diversions of the Ribeira River Flow and Their Influence on Sediment Supply in the Cananeia-Iguape Estuarine-Lagoonal System (SE Brazil)

et al. 2018

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The Cananéia-Iguape system is a combined estuarine-lagoonal sedimentary system, located along the SE coast of Brazil. It consists of a network of channels and islands oriented mainly parallel to the coast. About 165 years ago, an artificial channel, the Valo Grande, was opened in the northern part of this system to connect a major river of the region, the Ribeira River, to the estuarine-lagoon complex. The Valo Grande was closed with a dam and reopened twice between 1978 and 1995, when it was finally left open. These openings and closures of the Valo Grande had a significant influence on the Cananéia-Iguape system. In this study we present mineralogical, chemical, palaeomagnetic, and geochronological data from a sediment core collected at the southern end of the 50 km long lagoonal system showing how the phases of the opening and closure of the channel through time are expressed in the sedimentary record. Despite the homogeneity of the grain size and magnetic properties throughout the core, significant variations in the mineralogical composition showed the influence of the opening of the channel on the sediment supply. Less mature sediment, with lower quartz and halite and higher kaolinite, brucite, and franklinite, corresponded to periods when the Valo Grande was open. On the other hand, higher abundance of quartz and halite, as well as the disappearance of other detrital minerals, corresponded with periods of absence or closure of the channel, indicating a more sea-influenced depositional setting. This work represented an example of anthropogenic influence in a lagoonal-estuarine sedimentary system, which is a common context along the coast of Brazil.

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Magnetic methods and the timing of geological processes

Cited by 12 publications

References 130 publications

Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil

Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil

Multistratigraphic records of the Lower Cretaceous (Valanginian–Cenomanian) Puez key area in N. Italy

Diversions of the Ribeira River Flow and Their Influence on Sediment Supply in the Cananeia-Iguape Estuarine-Lagoonal System (SE Brazil)

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