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Ice or fire? Constraining the origin of isotopically anomalous cap carbonate cements by SIMS. / Cui, Huan; Orland, Ian J.; Denny, Adam; Kitajima, Kouki; Fournelle, John H.; Baele, Jean-Marc; De Winter, Niels; Goderis, Steven; Claeys, Philippe; Valley, John W.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5. Vol. 51 Denver Co. : Geological Society of America, 2019. p. 1-1.

Research output: Chapter in Book/Report/Conference proceedingConference paperResearch

Harvard

Cui, H, Orland, IJ, Denny, A, Kitajima, K, Fournelle, JH, Baele, J-M, De Winter, N, Goderis, S, Claeys, P & Valley, JW 2019, Ice or fire? Constraining the origin of isotopically anomalous cap carbonate cements by SIMS. in Geological Society of America Abstracts with Programs. Vol. 51, No. 5. vol. 51, Geological Society of America, Denver Co., pp. 1-1, Geological Society of America 2019 annual meeting, Phoenix, United States, 22/09/19. https://doi.org/10.1130/abs/2019AM-332456

APA

Cui, H., Orland, I. J., Denny, A., Kitajima, K., Fournelle, J. H., Baele, J-M., ... Valley, J. W. (2019). Ice or fire? Constraining the origin of isotopically anomalous cap carbonate cements by SIMS. In Geological Society of America Abstracts with Programs. Vol. 51, No. 5 (Vol. 51, pp. 1-1). Denver Co.: Geological Society of America. https://doi.org/10.1130/abs/2019AM-332456

Vancouver

Cui H, Orland IJ, Denny A, Kitajima K, Fournelle JH, Baele J-M et al. Ice or fire? Constraining the origin of isotopically anomalous cap carbonate cements by SIMS. In Geological Society of America Abstracts with Programs. Vol. 51, No. 5. Vol. 51. Denver Co.: Geological Society of America. 2019. p. 1-1 https://doi.org/10.1130/abs/2019AM-332456

Author

Cui, Huan ; Orland, Ian J. ; Denny, Adam ; Kitajima, Kouki ; Fournelle, John H. ; Baele, Jean-Marc ; De Winter, Niels ; Goderis, Steven ; Claeys, Philippe ; Valley, John W. / Ice or fire? Constraining the origin of isotopically anomalous cap carbonate cements by SIMS. Geological Society of America Abstracts with Programs. Vol. 51, No. 5. Vol. 51 Denver Co. : Geological Society of America, 2019. pp. 1-1

BibTeX

@inproceedings{be44e8bd26e44a28ab384abb65585e65,
title = "Ice or fire? Constraining the origin of isotopically anomalous cap carbonate cements by SIMS",
abstract = "The Marinoan glaciation (a.k.a. the Snowball Earth) represents a profound paleoclimatic anomaly in deep time. However, the detailed mechanism of its termination remains largely unknown. It was hypothesized that massive releases of methane via clathrate destabilization at ~635 Ma may have played a role in terminating the glaciation. A key piece of supporting evidence is the finding of methane-derived authigenic calcite cements (MDACCs, δ13Ccarb values down to –48‰) within the Marinoan cap carbonates in South China. However, a more recent study based on clumped isotope (Δ47) measurements suggests that the MDACCs are hydrothermal (T as high as 476 °C) in origin. If correct, the MDACCs cannot be used to infer paleoenvironments right after the glaciation. To test these contrasting hypotheses (ice vs. fire), we conducted a detailed investigation via μXRF, CL, SEM, and SIMS. The SIMS data show a 60‰ range of δ13Ccarb values with positive values (as high as +6.3‰) exclusively in dolomites and negative values (as low as –53.8‰) in calcites. Both the positive δ13Ccarb values and the lowest δ13Ccarb values are revealed in this study for the first time. Our results show that the dolomite crystals are typically euhedral, anomalously large (up to 200 μm) in size, have positive δ13Ccarb values, and are Mn-poor with dull or red luminescence under CL, with dolomite cores partly or almost completely replaced by low-δ13Ccarb calcite. The calcites have low δ13Ccarb values, are Mn-rich with bright orange luminescence under CL, showing multiple stages of vug-filling cements surrounding the preexisting dolomite crystals. These results suggest that the dolomites have been significantly recrystallized during burial or hydrothermal diagenesis and the MDACCs formed even later, postdating the recrystallized dolomites. We conclude that the MDACCs are post-depositional and formed during late diagenesis. Our conclusion is consistent with the prior work based on clumped isotope analysis. The present study casts further doubt on using MDACCs as evidence for methane clathrate in deep time. The role of methane in terminating the Snowball Earth should be re-assessed.",
keywords = "SIMS, Doushantuo Formation, Marinoan glaciation, Cap carbonates, Authigenic carbonates, methane, μXRF, SEM",
author = "Huan Cui and Orland, {Ian J.} and Adam Denny and Kouki Kitajima and Fournelle, {John H.} and Jean-Marc Baele and {De Winter}, Niels and Steven Goderis and Philippe Claeys and Valley, {John W.}",
year = "2019",
month = "9",
doi = "10.1130/abs/2019AM-332456",
language = "English",
volume = "51",
pages = "1--1",
booktitle = "Geological Society of America Abstracts with Programs. Vol. 51, No. 5",
publisher = "Geological Society of America",
address = "United States",

}

RIS

TY - GEN

T1 - Ice or fire? Constraining the origin of isotopically anomalous cap carbonate cements by SIMS

AU - Cui, Huan

AU - Orland, Ian J.

AU - Denny, Adam

AU - Kitajima, Kouki

AU - Fournelle, John H.

AU - Baele, Jean-Marc

AU - De Winter, Niels

AU - Goderis, Steven

AU - Claeys, Philippe

AU - Valley, John W.

PY - 2019/9

Y1 - 2019/9

N2 - The Marinoan glaciation (a.k.a. the Snowball Earth) represents a profound paleoclimatic anomaly in deep time. However, the detailed mechanism of its termination remains largely unknown. It was hypothesized that massive releases of methane via clathrate destabilization at ~635 Ma may have played a role in terminating the glaciation. A key piece of supporting evidence is the finding of methane-derived authigenic calcite cements (MDACCs, δ13Ccarb values down to –48‰) within the Marinoan cap carbonates in South China. However, a more recent study based on clumped isotope (Δ47) measurements suggests that the MDACCs are hydrothermal (T as high as 476 °C) in origin. If correct, the MDACCs cannot be used to infer paleoenvironments right after the glaciation. To test these contrasting hypotheses (ice vs. fire), we conducted a detailed investigation via μXRF, CL, SEM, and SIMS. The SIMS data show a 60‰ range of δ13Ccarb values with positive values (as high as +6.3‰) exclusively in dolomites and negative values (as low as –53.8‰) in calcites. Both the positive δ13Ccarb values and the lowest δ13Ccarb values are revealed in this study for the first time. Our results show that the dolomite crystals are typically euhedral, anomalously large (up to 200 μm) in size, have positive δ13Ccarb values, and are Mn-poor with dull or red luminescence under CL, with dolomite cores partly or almost completely replaced by low-δ13Ccarb calcite. The calcites have low δ13Ccarb values, are Mn-rich with bright orange luminescence under CL, showing multiple stages of vug-filling cements surrounding the preexisting dolomite crystals. These results suggest that the dolomites have been significantly recrystallized during burial or hydrothermal diagenesis and the MDACCs formed even later, postdating the recrystallized dolomites. We conclude that the MDACCs are post-depositional and formed during late diagenesis. Our conclusion is consistent with the prior work based on clumped isotope analysis. The present study casts further doubt on using MDACCs as evidence for methane clathrate in deep time. The role of methane in terminating the Snowball Earth should be re-assessed.

AB - The Marinoan glaciation (a.k.a. the Snowball Earth) represents a profound paleoclimatic anomaly in deep time. However, the detailed mechanism of its termination remains largely unknown. It was hypothesized that massive releases of methane via clathrate destabilization at ~635 Ma may have played a role in terminating the glaciation. A key piece of supporting evidence is the finding of methane-derived authigenic calcite cements (MDACCs, δ13Ccarb values down to –48‰) within the Marinoan cap carbonates in South China. However, a more recent study based on clumped isotope (Δ47) measurements suggests that the MDACCs are hydrothermal (T as high as 476 °C) in origin. If correct, the MDACCs cannot be used to infer paleoenvironments right after the glaciation. To test these contrasting hypotheses (ice vs. fire), we conducted a detailed investigation via μXRF, CL, SEM, and SIMS. The SIMS data show a 60‰ range of δ13Ccarb values with positive values (as high as +6.3‰) exclusively in dolomites and negative values (as low as –53.8‰) in calcites. Both the positive δ13Ccarb values and the lowest δ13Ccarb values are revealed in this study for the first time. Our results show that the dolomite crystals are typically euhedral, anomalously large (up to 200 μm) in size, have positive δ13Ccarb values, and are Mn-poor with dull or red luminescence under CL, with dolomite cores partly or almost completely replaced by low-δ13Ccarb calcite. The calcites have low δ13Ccarb values, are Mn-rich with bright orange luminescence under CL, showing multiple stages of vug-filling cements surrounding the preexisting dolomite crystals. These results suggest that the dolomites have been significantly recrystallized during burial or hydrothermal diagenesis and the MDACCs formed even later, postdating the recrystallized dolomites. We conclude that the MDACCs are post-depositional and formed during late diagenesis. Our conclusion is consistent with the prior work based on clumped isotope analysis. The present study casts further doubt on using MDACCs as evidence for methane clathrate in deep time. The role of methane in terminating the Snowball Earth should be re-assessed.

KW - SIMS

KW - Doushantuo Formation

KW - Marinoan glaciation

KW - Cap carbonates

KW - Authigenic carbonates

KW - methane

KW - μXRF

KW - SEM

U2 - 10.1130/abs/2019AM-332456

DO - 10.1130/abs/2019AM-332456

M3 - Conference paper

VL - 51

SP - 1

EP - 1

BT - Geological Society of America Abstracts with Programs. Vol. 51, No. 5

PB - Geological Society of America

CY - Denver Co.

ER -

ID: 46527622