U-Pb sensitive high-resolution ion microprobe ages from the Doushantuo Formation in south China: Constraints on late Neoproterozoic glaciations

Zhang, Shihong; Jiang, Ganqing; Zhang, Junming; Song, Biao; Kennedy, Martin J.; Christie‐Blick, Nicholas

doi:10.1130/g21418.1

Cited by 231 publications

(74 citation statements)

References 33 publications

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“…Both pre-Ediacaran-and DPM-type acanthomorphic acritarchs exhibit near-global but mutually exclusive distributions in shallow marine facies, separated by the 635-Ma (29,30) Marinoan glaciation. The oldest DPM-type acritarchs first appear in the lower Doushantuo Fm (55), in association with an ash bed recently dated at 635-627 Ma (30,56,57), and disappear from the record before 580 Ma (48). We note that the appearance of the DPM precedes the first (direct) record of eumetazoan fossils by as much as 55 myr (30), a not-unexpected gap, given the taphonomic challenges of preserving small nonbiomineralizing metazoans.…”

Section: Discussionmentioning

confidence: 99%

Origin of the Eumetazoa: Testing ecological predictions of molecular clocks against the Proterozoic fossil record

Peterson

Butterfield

2005

Proc. Natl. Acad. Sci. U.S.A.

326

219

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Molecular clocks have the potential to shed light on the timing of early metazoan divergences, but differing algorithms and calibration points yield conspicuously discordant results. We argue here that competing molecular clock hypotheses should be testable in the fossil record, on the principle that fundamentally new grades of animal organization will have ecosystem-wide impacts. Using a set of seven nuclear-encoded protein sequences, we demonstrate the paraphyly of Porifera and calculate sponge͞eumetazoan and cnidarian͞bilaterian divergence times by using both distance [minimum evolution (ME)] and maximum likelihood (ML) molecular clocks; ME brackets the appearance of Eumetazoa between 634 and 604 Ma, whereas ML suggests it was between 867 and 748 Ma. Significantly, the ME, but not the ML, estimate is coincident with a major regime change in the Proterozoic acritarch record, including: (i) disappearance of low-diversity, evolutionarily static, pre-Ediacaran acanthomorphs; (ii) radiation of the high-diversity, short-lived Doushantuo-Pertatataka microbiota; and (iii) an orderof-magnitude increase in evolutionary turnover rate. We interpret this turnover as a consequence of the novel ecological challenges accompanying the evolution of the eumetazoan nervous system and gut. Thus, the more readily preserved microfossil record provides positive evidence for the absence of pre-Ediacaran eumetazoans and strongly supports the veracity, and therefore more general application, of the ME molecular clock.Porifera ͉ acritarchs ͉ Ediacaran ͉ coevolution T he sudden appearance of diverse metazoan fossils Ϸ530 million years ago (Ma) is the focus of ongoing and heated debate: Is this recording a true ''Cambrian explosion'' of early metazoan evolution or merely the onset of extensive burrowing and biomineralization (1)? Certainly the invisibility of microscopic, nonburrowing, and͞or nonbiomineralizing metazoans in the fossil record allows for the possibility of deep Proterozoic origins, so independent lines of evidence must be sought. Molecular clocks offer a potentially powerful approach for testing such evolutionary hypotheses (2), but recent analyses have yielded conspicuously discordant results. Pisani et al. (3), for example, estimate that the protostome-deuterostome ancestor evolved 900-1,100 Ma, whereas Douzery et al. (4) place this node at 642-761 Ma and Peterson et al. (5) at Ϸ570 Ma. With estimated divergence times differing by Ͼ500 million years (myr), there is clearly a need to assess both the methods used and predictions made by individual molecular-clocks analyses.Pisani et al. (3) have argued that their deep estimate for metazoan origins is robust because it agrees with a previous analysis calibrated by using different taxa, i.e., between chick and mouse (6) vs. centipedes and millipedes and spiders and horseshoe crabs (3). However, Peterson et al. (5) demonstrated that a significant rate reduction is associated with the vertebrate sequences, such that a vertebrate-calibrated clock produces a spurious 2-fold ove...

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Section: Discussionmentioning

confidence: 99%

Origin of the Eumetazoa: Testing ecological predictions of molecular clocks against the Proterozoic fossil record

Peterson

Butterfield

2005

Proc. Natl. Acad. Sci. U.S.A.

326

219

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“…18. Carbon isotope data are given for Wushanhu (this study), Jijiawan (31), and Wuhe-Gaojiaxi (30). The MOSD position is marked within the dolostone sequence at the Wushanhu section.…”

Section: Methodsmentioning

confidence: 99%

“…At Jijiawan the 632.5-Ma age comes from a tuff bed in the shale unit at 5.0 m above the top of the 4.5-m-thick postglacial dolostones. Here, the dolostone δ 13 C data come from the same section (31) (Fig. 3).…”

Section: Mosd Durationmentioning

confidence: 99%

Sedimentary constraints on the duration of the Marinoan Oxygen-17 Depletion (MOSD) event

Killingsworth

Hayles

Zhou

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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The ∼635 Ma Marinoan glaciation is marked by dramatic Earth system perturbations. Deposition of nonmass-dependently 17 Odepleted sulfate (SO 4 2− ) in worldwide postglacial sediments is, thus far, unique to this glaciation. It is proposed that an extremely high-pCO 2 atmosphere can result in highly 17 O-depleted atmospheric O 2 , or the Marinoan Oxygen-17 Depletion (MOSD) event. This anomalous 17 O signal was imparted to sulfate of oxidative weathering origin. However, 17 O-depleted sulfate occurs in limited sedimentary intervals, suggesting that Earth surface conditions conducive to the MOSD had a finite duration. An MOSD duration can, therefore, provide much needed constraint on modeling Earth system responses at that time. Unfortunately, the sulfate 17 O record is often sparse or lacks radiometric dates. Here, we report 11 barite layers from a post-Marinoan dolostone sequence at Wushanhu in the South China Block. The 17 O depletion fluctuates in magnitude in lower layers but is persistently absent up section, providing the most confident first and last sedimentary appearance of the anomaly. δ 13 C chemostratigraphy is used to correlate the Wushanhu section to two proximal sections on the same shallow platform that lack barite layers but have published U-Pb dates that occur in dolostone and shale. Assuming a similar pattern and rate for carbonate and shale deposition among the different sections, we estimate the MOSD duration at 0-0.99 My. This number can be further constrained by new radiometric dates from equivalent sequences worldwide, thus underpinning models on the nonsteady-state Earth system response in the immediate aftermath of the Marinoan meltdown.T he Marinoan glaciation (∼635 Ma) may be the most extreme glacial period in Earth history, with widespread occurrence of glacial sediments at low paleolatitudes near the tropics (1). The central theme of the original snowball Earth hypothesis, which was developed to explain this glacial record, is the buildup of atmospheric CO 2 to bring the Earth out of an indefinite deep freeze (2). This idea has been expanded (3-5), undergone debate (1, 6), and driven new modeling work (7-14). Thanks to well-preserved sedimentary records (15, 16) and decent geochronological controls (17-19), many of the theories pertaining to the Marinoan glaciation can be tested.The most unusual evidence that is consistent with a snowball Earth hypothesis is the nonmass-dependently 17 A global occurrence of 17 O-depleted sulfate within post-Marinoan sedimentary sequences has been established by our recent findings in South China, West Africa, Svalbard, and Western Australia. This global occurrence is consistent with an event of atmospheric origin. In fact, the 17 O-depleted sulfate can be confidently used as a marker for a global synchronous event. However, although the anomalous sulfate occurs in one or two layers of barite or several horizons of dolostones, in all cases, it occurs only in limited intervals in the postglacial sediments. Viewed on the scale of geologic time, the MOSD...

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“…The Ediacaran fauna in the Yangtze Gorge is found in two formations. The upper Dengying Formation extends from the base of the Cambrian to about 551 MA (Condon et al 2005;Zhang et al 2005). The Doushantuo Formation extends from the base of the Dengying formation to about 635 MA.…”

Section: Time Of First Appearance Of Ediacaran Genera and Their Geolomentioning

confidence: 99%

“…The Doushantuo Formation extends from the base of the Dengying formation to about 635 MA. The Marinoan glaciation, which was a global event, was coming to an end at the base of the Doushantuo Formation (Condon et al 2005;Zhang et al 2005). All of the fossiliferous sites in both formations appear to have been shallow marine basins.…”

Section: Time Of First Appearance Of Ediacaran Genera and Their Geolomentioning

confidence: 99%

The rise of bilaterians

Freeman

2009

Historical Biology

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Recently Shen et al. have argued that the Ediacaran faunas from Avalon-Charnwood [580 -560 million years ago (MA)], the White Sea-Flinders Range (560-550 MA) and Namibia (550 -543 MA) occupied the same morphospace even though these faunas differed in species composition, ecology, biogeography and age. The traits they used to characterise these faunas could not distinguish between important promorphological features such as radial vs. bilaterian and unitary vs. colonial animals. Their inappropriate assignment of symmetry properties led to the homogenisation of morphospace in these different faunas. Another way to examine shifts in morphospace involves sorting out radial vs. bilaterian and unitary vs. colonial genera in terms of their time of first appearance in the fossil record. While genera with both kinds of symmetry properties and unitary and colonial animals were present during the early Ediacaran, there was a large proportional increase in new bilaterian genera and a decrease in colonial genera beginning between 560-550 MA. The increase in bilaterians may have been associated with the ability to exploit food sources in and on the substrate of shallow water environments.

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U-Pb sensitive high-resolution ion microprobe ages from the Doushantuo Formation in south China: Constraints on late Neoproterozoic glaciations

Cited by 231 publications

References 33 publications

Origin of the Eumetazoa: Testing ecological predictions of molecular clocks against the Proterozoic fossil record

Origin of the Eumetazoa: Testing ecological predictions of molecular clocks against the Proterozoic fossil record

Sedimentary constraints on the duration of the Marinoan Oxygen-17 Depletion (MOSD) event

The rise of bilaterians

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