Late Paleozoic remagnetization of Precambrian crystalline rocks along the Precambrian/Carboniferous nonconformity, Rocky Mountains: a relationship among deformation, remagnetization, and fluid migration

Geissman, J. W.; Harlan, Stephen S.

doi:10.1016/s0012-821x(02)00932-9

Cited by 22 publications

(38 citation statements)

References 49 publications

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“…Acquisition of magnetization after the formation of a rock, termed remagnetization, can obscure or remove the primary magnetizations and thus limit the utility of paleomagnetism in global (plate) tectonic reconstructions [ Elmore et al ., ; Font et al ., ]. Widespread remagnetization events are usually linked to large‐scale tectonic processes [ McCabe et al ., ; Miller and Kent , ; Chen and Courtillot , ; Appel et al ., ; Molina Garza and Zijderveld , ; Weil and Van der Voo , ; Font et al ., ; Rapalini and Bettucci , ; Font et al ., ] and can affect both sedimentary rocks [ Appel et al ., ; Gong et al ., ; Roberts et al ., ; Liu et al ., ; van der Voo and Torsvik , ] and igneous rocks [ Harlan et al ., ; Edel and Aifa , ; Geissman and Harlan , ; Otofuji et al ., ; Borradaile et al ., ; Preeden et al ., ]. Suspected mechanisms for remagnetization include elevated temperature, chemical alteration, and secondary mineral growth.…”

Section: Discussionmentioning

confidence: 99%

What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet)

et al. 2015

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The Paleogene latitude of the Lhasa terrane (southern Tibet) can constrain the age of the onset of the India-Asia collision. Estimates for this latitude, however, vary from 5°N to 30°N, and thus, here, we reassess the geochronology and paleomagnetism of Paleogene volcanic rocks from the Linzizong Group in the Linzhou basin. The lower and upper parts of the section previously yielded particularly conflicting ages and paleolatitudes. We report consistent 40 Ar/ 39Ar and U-Pb zircon dates of~52 Ma for the upper Linzizong, and 40 Ar/ 39 Ar dates (~51 Ma) from the lower Linzizong are significantly younger than U-Pb zircon dates (64-63 Ma), suggesting that the lower Linzizong was thermally and/or chemically reset. Paleomagnetic results from 24 sites in lower Linzizong confirm a low apparent paleolatitude of~5°N, compared to the upper part (~20°N) and to underlying Cretaceous strata (~20°N). Detailed rock magnetic analyses, end-member modeling of magnetic components, and petrography from the lower and upper Linzizong indicate widespread secondary hematite in the lower Linzizong, whereas hematite is rare in upper Linzizong. Volcanic rocks of the lower Linzizong have been hydrothermally chemically remagnetized, whereas the upper Linzizong retains a primary remanence. We suggest that remagnetization was induced by acquisition of chemical and thermoviscous remanent magnetizations such that the shallow inclinations are an artifact of a tilt correction applied to a secondary remanence in lower Linzizong. We estimate that the Paleogene latitude of Lhasa terrane was 20 ± 4°N, consistent with previous results suggesting that India-Asia collision likely took place by~52 Ma at~20°N.

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Section: Discussionmentioning

confidence: 99%

What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet)

et al. 2015

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“…A study of dolomite veins in the Precambrian-Early Palaeozoic Dalradian schist in Scotland reported a Carboniferous -Triassic CRM which was interpreted as being related to deep oxidizing weathering (Parnell et al 2000). Late Palaeozoic remagnetizations residing in haematite are also reported from crystalline rocks in North America and have been related to weathering fluids (Hamilton et al 2012) or to migration of brines along porous zones at the Precambrian-Carboniferous nonconformity (Geissman & Harlan 2002).…”

Section: Weathering Fluidsmentioning

confidence: 99%

Remagnetization and chemical alteration of sedimentary rocks

Elmore

Muxworthy

Aldana

2012

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Chemical remagnetization is a very common phenomenon in sedimentary rocks and developing a greater understanding of the mechanisms has several benefits. Acquisition of a secondary magnetization is usually tangible evidence of a diagenetic event that can be dated by isolation of the chemical remanent magnetization and comparison of the pole position to the apparent polar wander path. This can be important because diagenetic investigations are frequently limited by the difficulty in constraining the time frames in which most past events have occurred. Remagnetization can commonly obscure a primary magnetization; developing a better understanding of remagnetization could improve our ability to uncover primary magnetizations. Many chemical remagnetization mechanisms have been proposed, including those associated with chemical alteration by a number of different fluids (orogenic, basinal and hydrocarbons), burial diagenetic processes (clay diagenesis and maturation of organic matter) or other processes. This paper summarizes our current knowledge of these chemical remagnetization mechanisms, with a focus on examples where there is a connection with chemical alteration.

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“…Precipitation and growth of secondary hematite to produce CRMs during low‐temperature hydrothermal alteration of igneous rocks have been described by several workers [e.g., Edel and Schneider , ; Edel and Aifa , ; Geissman and Harlan , ; Ricordel et al ., ; Preeden et al ., ; Parcerisa et al ., ]. Edel and Schneider [] found that high laboratory unblocking temperature magnetizations carried by secondary hematite and hematized titanomagnetite could be isolated in Upper Carboniferous‐Lower Permian rhyolites from Northern Vosges (France).…”

Section: Discussionmentioning

confidence: 99%

“…Continuous overprinting due to low‐temperature alteration of titanomagnetite and crystallization of secondary hematite from the Middle Permian to Upper Permian was suggested to explain the resetting of the primary magnetization. In another example, Geissman and Harlan [] studied Precambrian crystalline units in the Rocky Mountains and suggested that magnetization of exclusively reversed polarity in those rocks was presumably acquired during the Permo‐Carboniferous reversed superchron. The dominant magnetic carrier of these plutonic rocks is secondary hematite, which was formed during migration of basinal fluids (at temperatures below 200°C) along regional nonconformities and fracture or fault zones in Precambrian basement rocks.…”

Section: Discussionmentioning

confidence: 99%

“…These processes can act alone or in concert, and they frequently result in changes in the magnetic mineralogy, in the NRM, or both [ Jackson and Swanson‐Hysell , ]. The severity of the problem is illustrated by widespread remagnetization events linked to large‐scale tectonic processes, which are common in orogens in North America [e.g., McCabe et al ., ; Miller and Kent , ; McCabe and Elmore , ; Elmore and McCabe , ; Elmore et al ., ; Geissman and Harlan , ; Evans et al ., ; Zechmeister et al ., ], South America [e.g., D'Agrella‐Filho et al ., ; Trindade et al ., ; Rapalini and Bettucci , ; Font et al ., , ; Tomezzoli et al ., ], Europe [e.g., Molina Garza and Zijderveld , ; Van der Voo et al ., ; Dinarès‐Turell and Garcia‐Senz , ; Weil and Van der Voo , ; Zegers et al ., ; Gong et al ., ; Zwing et al ., ; Roberts et al ., ], and Asia [e.g., Chen and Courtillot , ; Appel et al ., , ; Otofuji et al ., ; Torsvik et al ., ; Kim et al ., ; Liu et al ., ; Appel et al ., ; Kirscher et al ., ]. Therefore, proper identification of “remagnetized” and “nonremagnetized” rocks is critical to paleomagnetic research, particularly for paleogeographic reconstructions of continental blocks in convergent orogenic belts.…”

Section: Introductionmentioning

confidence: 99%

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Can a primary remanence be retrieved from partially remagnetized Eocence volcanic rocks in the Nanmulin Basin (southern Tibet) to date the India‐Asia collision?

et al. 2015

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Paleomagnetic dating of the India-Asia collision hinges on determining the Paleogene latitude of the Lhasa terrane (southern Tibet). Reported latitudes range from 5°N to 30°N, however, leading to contrasting paleogeographic interpretations. Here we report new data from the Eocene Linzizong volcanic rocks in the Nanmulin Basin, which previously yielded data suggesting a low paleolatitude (~10°N). New zircon U-Pb dates indicate an age of~52 Ma. Negative fold tests, however, demonstrate that the isolated characteristic remanent magnetizations, with notably varying inclinations, are not primary. Rock magnetic analyses, end-member modeling of isothermal remanent magnetization acquisition curves, and petrographic observations are consistent with variable degrees of posttilting remagnetization due to low-temperature alteration of primary magmatic titanomagnetite and the formation of secondary pigmentary hematite that unblock simultaneously. Previously reported paleomagnetic data from the Nanmulin Basin implying low paleolatitude should thus not be used to estimate the time and latitude of the India-Asia collision. We show that the paleomagnetic inclinations vary linearly with the contribution of secondary hematite to saturation isothermal remanent magnetization. We tentatively propose a new method to recover a primary remanence with inclination of 38.1°(35.7°, 40.5°) (95% significance) and a secondary remanence with inclination of 42.9°(41.5°,44.4°) (95% significance). The paleolatitude defined by the modeled primary remanence-21°N (19.8°N, 23.1°N)-is consistent with the regional compilation of published results from pristine volcanic rocks and sedimentary rocks of the upper Linzizong Group corrected for inclination shallowing. The start of the Tibetan Himalaya-Asia collision was situated at~20°N and took place by~50 Ma.

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Late Paleozoic remagnetization of Precambrian crystalline rocks along the Precambrian/Carboniferous nonconformity, Rocky Mountains: a relationship among deformation, remagnetization, and fluid migration

Cited by 22 publications

References 49 publications

What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet)

What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet)

Remagnetization and chemical alteration of sedimentary rocks

Can a primary remanence be retrieved from partially remagnetized Eocence volcanic rocks in the Nanmulin Basin (southern Tibet) to date the India‐Asia collision?

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