Sterkfontein is the most prolific single source of
Australopithecus
fossils, the vast majority of which were recovered from Member 4, a cave breccia now exposed by erosion and weathering at the ...landscape surface. A few other
Australopithecus
fossils, including the StW 573 skeleton, come from subterranean deposits T. C. Partridge
et al.
,
Science
300, 607–612 (2003); R. J. Clarke, K. Kuman,
J. Hum. Evol.
134, 102634 (2019). Here, we report a cosmogenic nuclide isochron burial date of 3.41 ± 0.11 million years (My) within the lower middle part of Member 4, and simple burial dates of 3.49 ± 0.19 My in the upper middle part of Member 4 and 3.61 ± 0.09 My in Jacovec Cavern. Together with a previously published isochron burial date of 3.67 ± 0.16 My for StW 573 D. E. Granger
et al.
,
Nature
522, 85–88 (2015), these results place nearly the entire
Australopithecus
assemblage at Sterkfontein in the mid-Pliocene, contemporaneous with
Australopithecus afarensis
in East Africa. Our ages for the fossil-bearing breccia in Member 4 are considerably older than the previous ages of ca. 2.1 to 2.6 My interpreted from flowstones associated with the same deposit. We show that these previously dated flowstones are stratigraphically intrusive within Member 4 and that they therefore underestimate the true age of the fossils.
China's historiographical traditions tell of the successful control of a Great Flood leading to the establishment of the Xia dynasty and the beginning of civilization. However, the historicity of the ...flood and Xia remain controversial. Here, we reconstruct an earthquake-induced landslide dam outburst flood on the Yellow River about 1920 BCE that ranks as one of the largest freshwater floods of the Holocene and could account for the Great Flood. This would place the beginning of Xia at ∼1900 BCE, several centuries later than traditionally thought. This date coincides with the major transition from the Neolithic to Bronze Age in the Yellow River valley and supports hypotheses that the primary state-level society of the Erlitou culture is an archaeological manifestation of the Xia dynasty.
The cave infills at Sterkfontein contain one of the richest assemblages of Australopithecus fossils in the world, including the nearly complete skeleton StW 573 ('Little Foot') in its lower section, ...as well as early stone tools in higher sections. However, the chronology of the site remains controversial owing to the complex history of cave infilling. Much of the existing chronology based on uranium-lead dating and palaeomagnetic stratigraphy has recently been called into question by the recognition that dated flowstones fill cavities formed within previously cemented breccias and therefore do not form a stratigraphic sequence. Earlier dating with cosmogenic nuclides suffered a high degree of uncertainty and has been questioned on grounds of sediment reworking. Here we use isochron burial dating with cosmogenic aluminium-26 and beryllium-10 to show that the breccia containing StW 573 did not undergo significant reworking, and that it was deposited 3.67 ± 0.16 million years ago, far earlier than the 2.2 million year flowstones found within it. The skeleton is thus coeval with early Australopithecus afarensis in eastern Africa. We also date the earliest stone tools at Sterkfontein to 2.18 ± 0.21 million years ago, placing them in the Oldowan at a time similar to that found elsewhere in South Africa at Swartkans and Wonderwerk.
The Tennessee River, a primary drainage of the southern Appalachians and significant sediment source for the Gulf of Mexico, is generally considered to be the product of captures that rerouted the ...river from a more direct gulfward course. Sedimentary and genetic evidence indicates that a paleo-Tennessee flowed into the Mobile Basin through the late Miocene, although alternate models propose other redirections of the river. We constrain the river course’s age by dating terraces near Pickwick, Tennessee, with cosmogenic 26Al/10Be isochron burial dating. We find that the river’s present path dates to at least the early Pliocene.
Frost et al. (1) show that molars of the East African Theropithecus oswaldi lineage become systematically larger from 4.0 to 0.5 My. They use this trend to infer ages for various South African fossil ...sites, assuming no clinal variation in tooth size over the continent. They estimate an age of ca. 2.4 My from the large T. oswaldi darti teeth at Makapansgat. Sterkfontein Members 4 and 2 lack Theropithecus but preserve other cercopithecid species similar to Makapansgat, so they propose a similar age, rejecting radiometric dates and stratigraphic observations (2) placing Sterkfontein Members 4 and 2 from ca. 3.4 to 3.7 My. We do not question that tooth size can be helpful for relative dating in East Africa but rather challenge the extrapolation of inferred ages to Sterkfontein. Frost et al. have based their age estimate for Sterkfontein mainly on paleomagnetism and U-Pb dating of flowstones and the presence of Cercopithecoides williamsi, "true" Papio, and Parapapio, which they compare with Makapansgat.
The Early Pleistocene site of Swartkrans in South Africa’s Cradle of Humankind World Heritage Site has been significant for our understanding of the evolution of both early Homo and Paranthropus, as ...well as the earliest archaeology of southern Africa. Previous attempts to improve a faunal age estimate of the earliest deposit, Member 1, had produced results obtained with uranium-lead dating (U–Pb) on flowstones and cosmogenic burial dating of quartz, which placed the entire member in the range of >1.7/1.8 Ma and <2.3 Ma. In 2014, two simple burial dates for the Lower Bank, the earliest unit within Member 1, narrowed its age to between ca. 1.8 Ma and 2.2 Ma. A new dating program using the isochron method for burial dating has established an absolute age of 2.22 ± 0.09 Ma for a large portion of the Lower Bank, which can now be identified as containing the earliest Oldowan stone tools and fossils of Paranthropus robustus in South Africa. This date agrees within one sigma with the U–Pb age of 2.25 ± 0.08 Ma previously published for the flowstone underlying the Lower Bank and confirms a relatively rapid rate of accumulation for a large portion of the talus.
The age of Zhoukoudian Homo erectus, commonly known as 'Peking Man', has long been pursued, but has remained problematic owing to the lack of suitable dating methods. Here we report cosmogenic ...(26)Al/(10)Be burial dating of quartz sediments and artefacts from the lower strata of Locality 1 in the southwestern suburb of Beijing, China, where early representatives of Zhoukoudian Homo erectus were discovered. This study marks the first radioisotopic dating of any early hominin site in China beyond the range of mass spectrometric U-series dating. The weighted mean of six meaningful age measurements, 0.77 +/- 0.08 million years (Myr, mean +/- s.e.m.), provides the best age estimate for lower cultural layers 7-10. Together with previously reported U-series dating of speleothem calcite and palaeomagnetic stratigraphy, as well as sedimentological considerations, these layers may be further correlated to S6-S7 in Chinese loess stratigraphy or marine isotope stages (MIS) 17-19, in the range of approximately 0.68 to 0.78 Myr ago. These ages are substantially older than previously supposed and may imply early hominin's presence at the site in northern China through a relatively mild glacial period corresponding to MIS 18.
Abstract
The formation of magma‐poor continental rifts is an enigmatic process, as the weakening mechanism(s) for cratonic lithosphere remains uncertain in the absence of elevated lithospheric ...temperature. One view links weakening to melts hidden at depth, while another ascribes it to pre‐existing weaknesses. Long‐term extensional rates also influence lithospheric strength and rift evolution. We target the Linfen Basin (LB) in the magma‐poor Shanxi Rift System (SRS) in the North China Craton to understand these components. We apply cosmogenic
26
Al/
10
Be burial dating on 14 core samples at different depths from three deep boreholes in the basin and obtain six valid burial ages ranging from 2.37
+1.18/−1.21
to 5.86
+inf/−1.37
Ma. We further re‐interpret a seismic reflection profile and quantify the geometry and amount of extension by forward structural modeling with multiple constraints based on extensional fault‐bend folding theory. The timing of the basal sedimentation is estimated to be ∼6.1 and ∼4.2 Ma in the southern and northern portions, respectively, indicating diachronous, northward‐propagating rifting. The amount and mean rate of extension are ∼3.6 km and ∼0.9 km/Myr, respectively. The basin depths increasing northward indicates the clockwise rotation of the basin. We propose a basin‐scale non‐rigid transtensional bookshelf faulting model to explain the rotation patterns of the circum‐Ordos basins. We argue that the inherited structures weaken the cratonic lithosphere of the SRS, and the low extension rate contributes to its magma‐poor nature. We propose a lithospheric‐scale evolution model for the LB, invoking the inherited crustal weakness, low extension rate, and lower lithosphere counterflow.
Plain Language Summary
Continental rifting is an important part of plate tectonics. Scientists are still trying to understand how magma‐poor continental rifts happen because the tectonic forces available are not enough to stretch the strong lithosphere (outer layer of the Earth). We take the Linfen Basin (LB) in the magma‐poor Shanxi Rift System (SRS) in North China as an example to study this issue. We find the basin bottom ages are about 6.1 million years in the south and 4.2 million years in the north, indicating northward propagation of the rift basin. The basin extended by about ∼3.6 km at an average rate of 0.9 km per million years. Not only the LB but also the circum‐Ordos basins are rotating accordantly. We propose a basin‐scale non‐rigid transtensional bookshelf faulting model to explain their rotation pattern. We argue that the pre‐existing, old structures made the SRS's lithosphere weaker, and the slow extension rate contributes to its magma‐poor nature. We finally propose a model for how the LB developed over time, which takes into account the crustal weakness caused by the pre‐existing structures, slow extension rate, and counterflow in the lower lithosphere.
Key Points
Basal sediments in the Linfen Basin (LB) yield ∼4.2 and ∼6.1 Ma burial ages, indicating diachronous, northward‐propagating extension
Fault‐bend folding theory‐based seismic interpretation yields ∼3.6 km extension at a mean rate of ∼0.9 km/Myr across the basin
The LB of the Shanxi Rift System may be a natural example of the lower lithospheric counterflow model
Rock uplift rates can be difficult to measure over 103-105 yr time scales. If, however, a landscape approaches steady state, where hillslope erosion and rock uplift rates are steady and locally ...similar, then it should be possible to quantify rock uplift rates from hillslope erosion rates. Here, we test this prediction by comparing channel steepness index values and 10Be catchment-averaged erosion rates to well-constrained rock uplift rates in two landscapes in Italy. The first field area is the Romagna Apennines, northern Italy, where rock uplift rates are relatively uniform, between 0.2 and 0.5 mm/yr (regional mean 0.40±0.15 SE mm/yr), and have been steady since 0.9 Ma. The second area is the region around northeastern Sicily and the southernmost Italian peninsula, where rock uplift rates are higher and exhibit a strong spatial gradient, from ∼0.7 to ∼1.6 mm/yr (regional mean 1.09±0.13 SE mm/yr). In both regions, channel steepness indices and 10Be erosion rates vary directly with rock uplift rates. Although there is considerable variability in erosion rates, regionally averaged rates in both the northern (0.46±0.04 SE mm/yr) and southern (1.21±0.24 SE mm/yr) areas accurately measure rock uplift rates. Although channel steepness indices do not quantify rock uplift rates, they are useful for (1) identifying regional patterns of rock uplift, (2) identifying areas where uplift rates might be expected to be uniform, and (3) informing 10Be sampling strategies. This study demonstrates that, together, channel steepness and hillslope erosion rates can provide a powerful tool for determining rock uplift rates.
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