U-Pb dating of detrital zircons from the Wudangshan Group in the

Transcription

Article
Geochemistry
August 2010 Vol.55 No.22: 2440−2448
doi: 10.1007/s11434-010-3095-6
SPECIAL TOPICS:
U-Pb dating of detrital zircons from the Wudangshan Group in
the South Qinling and its geological significance
LING WenLi1,2*, DUAN RuiChun1,3, LIU XiaoMing1,4, CHENG JianPing1, MAO XinWu5,
PENG LianHong5, LIU ZaoXue5, YANG HongMei1,3 & REN BangFang1,6
1
Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China;
State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Wuhan 430074, China;
3
Yichang Institute of Geology and Mineral Resources, Yichang 443003, China;
4
State Key Laboratory of Continental Geodynamics, Northwest University, Xi’an 710069, China;
5
Geological Survey of Hubei Province, Wuhan 430022, China;
6
Tianjin Institute of Geology and Mineral Resources, Tianjin 300170, China
2
Received November 16, 2009; accepted December 22, 2009
U-Pb dating was made by the LA-ICP-MS method for detrital zircons from the Wudangshan volcanic-sedimentary succession in
the South Qinling. Samples comprise quartz sandstones of the Wudangshan Group collected from the base of the Yangping Formation and an upper layer of the Shuangtai Formation overlain its volcanic sequence, and two river-sand collections from the
drainage systems cutting across the two formations, respectively. The results show that the Yangping detrital zircons are dominated by 830–780 Ma grains with a minor population of ~1.0–0.84 Ga and sporadic grains of ~2.6, ~2.4 and 2.0 Ga, whereas the
Shuangtai zircons yield an upper intercept age of 763±33 Ma, identical to the timing of the Wudangshan volcanism within error,
with few concordant grains of 1.9 and 0.86 Ga. Age spectra for the two river-sand samples are similar to those of the Yangping
and Shuangtai Formations, respectively. It thus suggests that the Wudangshan strata are less than 780 Ma, whereas their major
detrital zircon populations of 1.0–0.85 Ga and 830–780 Ma are consistent with timing of the Hannan magmatic activities along
the northwestern margin of the South China Block. This suggests a Hannan or adjacent area provenance for the Wudangshan
strata. The Wudang area is characterized by rift-related igneous events at ~755 and ~680 Ma, respectively, pointing to a tectonomagmatic history different from the Hannan area. It is inferred that the ~755 Ma magmatism is likely to indicate a separation of
the South China Block from the supercontinent Rodinia, while the ~680 Ma event suggests a further split between the South
Qinling and some unknown continent.
Detrital zircon, U-Pb geochronology, South Qinling, South China Block, Neoproterozoic evolution
Citation:
Ling W L, Duan R C, Liu X M, et al. U-Pb dating of detrital zircons from the Wudangshan Group in the South Qinling and its geological significance.
Chinese Sci Bull, 2010, 55: 2440−2448, doi: 10.1007/s11434-010-3095-6
It is well known that the Qinling-Dabie-Sulu orogenesis
played an important role in east-central China’s continental
configuration and evolution, particularly amalgamation between the North China Block (NCB) and the South China
Block (SCB) and a transformation of lithospheric tectonic
regime during the Mesozoic [1–6]. However, a number of
essential issues remain controversial, including the dis*Corresponding author (email: [email protected])
© Science China Press and Springer-Verlag Berlin Heidelberg 2010
chronous collisions in the Qinling and Dabie-Sulu orogenic
belts, comparison between the tectonic units and positions
along the continental suture zone. In fact, these disputes are
principally due to our poor understanding of the attributes
of diverse Qinling tectonic units. For instance, whether the
North-and South Qinling units were the orogen-involved
segments from the two blocks or independent micro-continents? Although arc-and rift-related igneous activities at 1.0 to 0.78 Ga intensively occurred along the northcsb.scichina.com
www.springerlink.com
LING WenLi, et al.
Chinese Sci Bull
ern margin of the SCB, these events are lacking in the adjacent South Qinling. It is also notable that Neoproterozoic
zircons hosted by the Triassic eclogites in the Dabie-Sulu
orogenic belt have been used as a critical indicator of the
SCB subduction beneath the NCB. However, there are two
difficulties in this inference: (1) if the Qinling and the
Dabie-Sulu belts were co-genetic and the South Qinling was
the orogen-involved segment from the SCB, the subducted
block should show a South Qinling affinity [7]. However,
the Neoproterozoic affinity between the South Qinling and
the northern SCB remains unclear; and (2) a large amount
of the Neoproterozoic zircons hosted by the Dabie-Sulu
eclogites are ~750 and ~680 Ma [8–10], but these ages have
not been documented along the northern SCB margin next
to the South Qinling. Thus, more detailed studies of the
Qinling tectonic unites, especially the late Precambrian history, are critical to understanding of the Phanerozoic continental convergence and the tectonic transformation in
east-central China. Besides, a Neoproterozoic correlation
study between the South Qinling and SCB would also provide new constraints on the connection models of South
China with Rodinia.
In the South Qinling, the largest Precambrian terrain occurs at the Wudang area. The Wudangshan Group dominates the South Qinling deformed basement [3], on which a
number of studies have been documented [11–14]. The
Wudangshan volcanic-sedimentary succession experienced
a regional metamorphism varying from lower to upper
greenschist facies, while intensive deformation has transformed the strata to NW-trending tight folds and faults.
Previous age data are highly controversial, which is markedly illustrated by a ~1.0 Ga difference between volcanic
rocks collected from the southern-and northern Wudang
area, respectively [13]. The present authors recently reported a comprehensive U-Pb zircon study of volcanic rocks
collected from the main cross sections of the Wudangshan
strata, which exclusively reveals a ~755 Ma igneous timing
[15]. However, the depositional age and provenance of the
lower Wudangshan strata are still poorly constrained due to
a ~2500 m stratigraphy thickness and that the volcanic sequence occurs only at the upper strata. This work reports a
U-Pb detrital zircon geochronology of the Wudangshan
sedimentary succession. The samples comprise sandstones
from the Yangping- Shuangtai Formations of the lower and
mid-upper strata, respectively, and river sands deposited
within two local water systems cutting across these two
formations, respectively. The aims of this study were to (1)
depict the U-Pb geochronology of the Wudangshan detrital
zircons and constrain the maximum age of the strata; (2)
compare their Neoproterozoic spectra with the timing of the
synchronous igneous activities that occurred along the
northern SCB margin, thus to analyze their provenance correlation with the SCB Precambrian basement; and (3) explore the correlation of the South Qinling and SCB during
the Neoproterozoic as well as their linkage with Rodinia
August (2010) Vol.55 No.22
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breakup.
1 Regional geology
The North and South China Blocks are separated by the
E-W trending Qinling-Dabie-Sulu orogen, which is disconnected by the Nanyang basin. The orogen is suggested to
have been finally formed by the closure of easternmost Paleo-Tethys [1,2,6]. Form the north southward, the Qinling
orogenic belt comprises tectonic units of the southern margin of the NCB, North Qinling, South Qinling and the
northern margin of the SCB (Figure 1).
The South Qinling borders the North Qinling and the
northern margin of the SCB along the Shangdan suture to
the north and the Mianlue suture to the south, respectively.
These sutures are inferred to have been formed by the Middle Paleozoic collision between the NCB and the South
Qinling and the Late Triassic collision between the South
Qinling and the SCB, respectively [6]. The Wudang area is
situated at the eastern extremity of the South Qinling and
typical of an inlier. The uplift center comprises the Wudangshan Gp surrounded by the Nanhua-Sinian to Phanerozoic strata (Figure 1). The Wudangshan Gp comprises
the oldest base of the outcropped strata in the region and the
largest Precambrian suites (~8000 km2) in the South Qinling.
From bottom upward this volcanic-sedimentary succession
is subdivided into the Yangping, Shuangtai and Lanyuhe
Formations. The Yangping Fm comprises quartz sandstone,
feldspathic-quartz sandstone, arkose, siltstone, and sericite
(-quartz) schist with minor marble layers. The Shuangtai
Fm consists of bimodal volcanic sequence intercalated with
fine-grain sedimentary beds, whereas the Lanyuhe Fm is
dominated by greywacke, quartzofeldspathic sandstones and
finegrain rocks. The Yaolinghe succession overlies the
Wudangshan strata by an unconformity contact, and consists of dominatively basaltic lavas interbedded with minor
silicic volcanic and schist layers. Both the Wudangshan and
Yaolinghe Gps were intruded by doleritic-gabbroic sills,
and all these suites suffered greenschist facies metamorphism and were overlain by the Nanhua-Sinian to Phanerozoic covers. The Wudangshan and the Yaolinghe volcanisms were dated at 755±3 Ma and 685±7 Ma, respectively,
while the mafic sills at 679 ±3 Ma [15].
2 Sampling and analysis methods
Samples comprise two sandstones (WD05-64 and WD05-65)
from the base of the Yangping Fm in the south, one feldspathic-quartz (WD05-14) from the upper Shuangtai Fm in
the southwest, and two river-sands (WD05-S1 and
WD05-S2) from two water systems cutting across these two
formations, respectively (Figure 1). The rocks for detrital
zircons analysis were crushed and separated using standard
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Figure 1 Sketch geological map of the Wudangshan area in the South Qinling [12] showing sampling locations (c). (a) and (b) show tectonic positions of
the Qinling-Dabie orogen and the Wudang area, respectively. 1, Wudangshan Gp; 2,Yaolinghe Gp; 3, mafic sill; 4, the sinian; 5, intermediate-acid intrusion;
6, Phanerozoic sedimentary succession; 7, reservoir; 8, fault; 9, sampling location of this study; 10, sampling location of the Wudang igneous suites [15]; 11,
approximate range of the sampled local water-system.
techniques of density and magnetic discrimination. The final concentrates were handpicked under a binocular microscope. The zircon grains were mounted in epoxy resin with
zircon standard 91500 and silicate glass standard NIST
SRM610. After polishing, the zircon grains were examined
by cathodoluminescence (CL) to detect cores, rims and
other complexities might be present and select suitable laser
ablation spots during in situ analysis of U-Pb isotope. The
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CL imaging was performed at the State Key Laboratory of
Continental Dynamics (LCD), Northwest University (Xi’An,
China) using Quanta 400FEG SEM. Analysis of U-Pb detrital zircon was carried out at LCD using ELA-ICPMS.
Laser-ablation system comprises GeoLas 200M equipped
with a 193 nm ArF-excimer laser and is coupled with an
Agilent 7500a ICP-MS. The laser spot diameter was 30 μm.
Each analysis includes a background acquisition interval of
approximately 30 s and a signal acquisition of about 80 s.
Raw data were processed using the Glitter (REV 4.0) software [16]. Apparent and discordia U-Pb ages were calculated by the ISOPLOT program (REV. 4.9) [17]. All measurements were performed using zircon 91500 as the external
standard with a 206Pb/238U age of 1065.4±0.6 Ma [18]. The
standard silicate glass NIST SRM610 was used to calculate
U, Th and Pb concentrations. The detailed analytical method was described elsewhere [19].
3 U-Pb geochronology of detrital zircon
The measured U-Pb isotopic data and corresponding apparent ages for 179 zircons from the sandstones and 183 grains
from the river-sands are listed in Table S1.
3.1
Yangping sandstone
Analyses of 59 grains from WD05-64 g an age range from
2.55 Ga to 780 Ma (Figure 2a). All zircons are concordant
or near concordant except two grains, which display
207
Pb/206Pb and 206Pb/238U apparent ages of 1975±32 Ma,
2022±33 Ma and 1741±14 Ma, 1828±15 Ma, respectively.
Of the concordant zircons, 5 grains consist of the oldest
population ranging 2555–2380 Ma (206Pb/238U age, the same
below). These grains are olivary round and display weak CL
images with accreted light thin rims (Figure 3a1, a2). The
second population comprises 8 grains giving ages of 2071–
2032 Ma. Their surfaces are rounded and pitted, while their
CL images show well-developed oscillatory zoning or sectors typical of magmatic genesis (Figure 3a3–a5). The remaining zircons are Neoproterozoic and can be further divided into two populations of 1045–855 and 830–780Ma,
respectively. The former population (15 grains) has subhedral to rounded surfaces with stubby form. Their CL images are variable with relatively faint composition zoning and
tiny inclusions (Figure 3a6–a8). In contrast, the later population (24 grains) are euhedral and elongate with relatively
intact prisms, pyramids and well defined oscillatory zones
(Figure 3a9–a11), indicating a short distance provenance.
Analyses of 68 zircons from WD05-65 display age spectra similar to WD05-64 (Figure 2b). One grain gives an Archean age of 2631±13 Ma. It is a rounded surface and elongate crystal with light CL image but featureless internal
core and gray accreted rim (Figure 3b1). Three grains give
ages from 2003 to 2023 Ma comparable with the second
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population of the WD05-64 spectra. These zircons are
rounded and pitted with light but recognizable oscillatory
zoning core and gray accreted rim (Figure 3b2). The spectra
are dominated by Neoproterozoic grains, which can be also
divided into two populations. Ten grains of 903–841 Ma are
stubby to elongate with rounded surfaces. Their CL images
show blurred oscillatory zoning (Figure3b3, b4). The largest
population of 831–777 Ma comprises 51 grains, comparable
with the younger Neoproterozoic population of WD05-64.
These grains are variable elongate from euhedral with relatively intact prisms and pyramids to rounded surfaces, and
characterized by well defined oscillatory zones (Figure 3b5–
b7).
3.2
Shuangtai sandstone
Sample WD05-14 was collected from a sandstone layer
overlying the volcanic sequence within the Shuangtai Fm
along the stratotype section. Analyses of 52 grains were
carried out. Compared with the Yangping sandstones, most
grains from WD05-14 are tiny in size (< 100 μm). Two
grains give ages (206Pb/238U) of 1781±22 Ma and 861±11
Ma, respectively (Figure 2c). The older grain is moderately
discordant (207Pb/206Pb age of 1915±54 Ma) with rounded
surface but oscillatory zoning core and wide accreted rim
(Figure 3 c1), whereas the younger is concordant with subhedral surface, zoning oscillatory core and thin accreted rim
(Figure 3c2). The remaining grains are characterized by
discordant U-Pb composition with 206Pb/238U apparent ages
from 732 to 453 Ma (Figure 2c). These grains are euhedral
with well-defined oscillatory zoning (Figure 3c3, c4). On
the concordia diagram, however, the grains give a well defined upper intercept age of 763±33 Ma, identical to the timing of the Wudangshan volcanism within analysis error [15].
3.3
Sandy zircons
Though it is likely that the river sands may contain zircons
from previously eroded rocks, river detrital zircon analysis
is still a valuable approach to assess possible sampling bias
and provide age spectra representative of a wider range of
the Wudangshan rocks. Sand WD05-S1 was collected from
a river system chiefly cutting across the Shuangtai Fm and
its covers. Of the 105 analyses (Figure 2d), one subhedral
grain show faint but recognizable oscillatory zoning and
give concordant ages of 1748±12 Ma and 1724±12 Ma for
its core and rim, respectively (Figure 3d1), while another
grain yields an age of 869t±8 Ma and is characterized by
rounded surface and light oscillatory zoning (Figure 3d2).
The remaining concordant zircons can be divided into four
populations with weighted mean ages of 792±4 Ma (95%
confidence, n=12, MSWD=2.3), 748±3 Ma (n=55,
MSWD=6.8), 680±5 Ma (n=19, MSWD=6.0) and 582±3 Ma
(n=3, MSWD=1.1), respectively. These grains are euhedral
and stubby to elongate forms with well-developed oscillatory
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Figure 2 Concordia diagrams for detrital zircons from the Yangping (a,b) and Shuangtai (c) Fms of the Wudangshan Gp and river sands of the local water
systems (d–e).
zoning (Figure 3d3, d4 for population ~792 Ma, Figure 3d5,
d7 for population ~748 Ma, Figure3d8 for population ~680
Ma and Figure 3d9 for population ~582 Ma). The data suggest that their provenances are primarily the Wudangshan
volcanics (~750 Ma), and subordinately the Yaolinghe volcanics and the intrusive sills (~680 Ma), whereas the ~790
Ma grains indicate an inherited origin previously hosted by
these igneous rocks. It is notable that ~580 Ma magmatism
has not been reported in this region. A further work is
needed to assess the possible magmatism occurring at the
Neoproterozoic-Cambrian transition though it is likely a
less intensive igneous event.
Sample WD05-S2 was collected from a river system
mainly cutting across the Yangping Fm. The age spectra
comprise 78 analyses and show features similar to
WD05-64 (Figure 2). Two concordant grains are 2378±16
and 2376±31 Ma, respectively, with rounded surfaces and
oscillatory zoning core and dark gray accreted rims (Figure
3e1–e2). The second population consists of 17 grains ranging
from 2056 to 1971 Ma (weighted mean age of 2011±14 Ma,
MSWD=9.7). Most zircons are fragments of larger crystals
and vary from subhedral to rounded in form and well-defined
to faint oscillatory zonings (Figure 3e3, e4). Three grains
display discrete ages of 1867±11 Ma, 1839±12 Ma and
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Figure 3
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CL images for detrial zircons from the Yangping and Shuangtai Fms of the Wudangshan Gp and river sands of the local water systems.
1690±19 Ma, respectively, and show forms and CL images
similar to the previous population. A 11-grain population
displays a successive cluster from 971 to 881 Ma, showing
rounded surfaces and clean oscillatory zoning or sectors
(Figure 3e5, e6). The largest population consists of 39
grains ranging from 835 to 773 Ma. These zircons show forms
of rounded stubby to euhedral elongate with well-developed
oscillatory zoning (Figure 3e7, e8).
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Chinese Sci Bull
High similarity in age spectra between the detrital zircons from the sandstones and the river-sand, respectively,
suggests that both approaches are effective for provenance
tracing.
4 Discussion
4.1 Maximum depositional age and stratigraphic sequence of the Wudangshan Gp
The Wudangshan Gp is one of the key units to understand
the Precambrian history of the South Qinling. However,
whether the Wudangshan Gp in fact consists of diverse age
volcanic-sedimentary suites (Mesoproterozoic to Neoproterozoic [13]) and if the Yangping Fm overlies or underlies
the Shuangtai Fm (normal or reverse sequence [11]) remain
hot issues for debate. A recent study by the present authors
has shown that the volcanic rocks collected from 5 diverse
cross sections of the Wudangshan Gp were exclusively
formed at ~755 Ma [15], while the results here reveal that
the youngest detrital zircons from the Yangping and
Shuangtai Fms are ~780 and ~755 Ma, respectively. Besides, the coevality between the Shuangtai detrital zircons
and the Shuangtai volcanism infers an intra-formation
provenance by rapid erosion. These suggest that the whole
strata of Wudangshan Group are Neoproterozoic with a
maximum age less than 780 Ma; the strata have a normal
stratigraphic sequence, i.e. the Yangping Fm is overlain by
the Shuangtai Fm.
4.2 Neoproterozoic correlation of the South Qinling
with the northern SCB margin
As previously mentioned, contrasting views (i.e. independent micro-continent [1,6] versus orogen-involved segment
[20,21]) have been proposed on the South Qinling-SCB
relation. Figure 4 illustrates U-Pb age histograms for the
detrital zircons along with that for the inherited zircons
hosted by the Wudangshan, Yaolinghe volcanic suites and
the intrusive sills [15]. As a whole, the zircons can be divided into four groups of ~2.4, 2.0–2.2, 1.7–1.8 and
0.78–1.0 Ga, respectively. Well documented data have revealed that the Paleoproterozoic to Mesoproterozoic magmatic activities were variably recorded both in the NCB
[22–26] and SCB [27–30]. Hence it is difficult to use these
ages to trace the sedimentary provenance of the Wudangshan succession. However, the cluster range of 1.0–0.78 Ga
for the largest detrital zircon population is comparable with
the timings of the Neoproterozoic igneous activities widely
occurred in the SCB. Zircons with this age range from the
Dabie metamorphic rocks have been used to identify as a
SCB affinity for the host rocks [31,32]. The igneous activities occurred at ~1.0–0.9 Ga and 0.83–0.78 Ga have been
suggested to be arc-and rift-related, respectively [33–35],
though divergent views both on the timing and tectonic set-
Figure 4 U-Pb age spectrum histograms for detrital zircons from the
Shuangtai (a) and Yangping (b,c) Fms and the local river sands (d,e) comparing with that for the inherited zircons from the Neoproterozoic Wudang
igneous suites [15](f).
ting remain [36–38]. It was also alternatively proposed that
arc-related and arc-continent collision-related magmatisms
occurred at 1.3–1.0 and 0.97–0.86 Ga, respectively, during
the Rodinia assemblage, while the 0.83–0.74 Ga igneous
suites were formed by post-collision magmatism resulted
from the orogen collapse due to lithospheric extension [38].
Actually, ~1.0–0.78 Ga igneous activities were successively
recorded only in the Hannan of the northern SCB margin
[35] and in the southeastern SCB (i.e. Jiangnan orogen). Of
the ~750 Ma events, those occurred in the western [39] and
northern (the Dabie orogen) [9] margins of the SCB are
suggested to be rift-related, whereas those occurred in the
LING WenLi, et al.
Chinese Sci Bull
southeastern margin to be orogen collapse-related [32,38].
The abundant 1.0–0.78 Ga detrital/inherited zircons thus
suggest that the Wudangshan strata had a Hannan-like
provenance, and that the Wudang area has a basement comprising rocks resembling the Hannan Neoproterozoic igneous suites. Hence it is proposed that the South Qinling was a
marginal segment of the SCB during the early Neoproterozoic.
4.3 Linkage of the Neoproterozoic South Qinling with
Rodinia breakup
It is notable that ~680 Ma magmatism is uniquely recognized in the South Qinling, while ~750 magmatic suites are
restricted to the Yangtze marginal areas (i.e. the western
Sichuan [39], the Dabie [8,9] and Jiangnan orogenic belts
[32,38,40]). This implies that the South Qinling experienced
a tectonic evolution different from the SCB during the
mid-late Neoproterozoic. Accordingly, the ~750 and 680
Ma zircons hosted by eclogitic suites in the Dabie-Sulu
orogenic belt suggest that the subducted continental segment has a South Qinling affinity. A number of studies have
shown that the ~680 Ma Yaolinghe and the intrusive magmatisms were rift-related [12,15,41–44]. Though synchronous rocks are lacking within the SCB, ~680 Ma magmatisms have been reported on the Seward Peninsula in
northwestern Alaska [45] and in the southern to central Appalachians of eastern North America [46]. These suites are
suggested to be comparable with the magmatic belt in eastern North America and the Svalbard, which were resulted
from a separation from the Laurentia during Rodinia
breakup [46]. In addition, a large-scale mafic dyke swarm
occurs at the Mundine Well, northwestern Australia. It was
dated at 755±3 Ma [47] and suggested to be a mantle
plume-related origin [48]. We thus propose that the ~755
Ma magmatic event indicates a separation of the northern
SCB margin from Rodinia, while the ~680 Ma event likely
implies a further split between the South Qinling and some
unknown continent [15].
This paper has benefited from the scientific comments of two anonymous
reviewers and the editorial committee. We appreciate the help of Deng Q.
Z., Cheng T. L. and He R. L. in field works. This work was supported by the
National Natural Science Foundation of China (40373015, 40673025 and
40821061) and the Ministry of Education of China and the State Administration of Foreign Expert Affairs of China (B07039).
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Supporting Information
Table S1
Detrital zircon U-Pb compositions and apparent ages of the Wudangshan Gp sedimentary rocks and the local water systems
The supporting information is available online at csb.scichina.com and www.springerlink.com. The supporting materials
are published as submitted, without typesetting or editing. The responsibility for scientific accuracy and content remains entirely with the authors.
LING WenLi, et al.
Table S1
No.
Chinese Sci Bull
2449
Detrital zircon U-Pb compositions and apparent ages of the Wudangshan Gp sedimentary rocks and the local water systems
207
Pb/206Pb±1σ
WD05-64
1
0.0771
2
0.0702
3
0.0713
4
0.0646
6
0.0682
7
0.0667
8
0.1602
9
0.0667
10
0.0672
11
0.0684
12
0.0688
13
0.0679
14
0.0712
15
0.0701
16
0.0737
17
0.0689
18
0.0687
19
0.0672
20
0.0651
21
0.0653
22
0.1551
23
0.1252
24
0.0660
25
0.1243
26
0.0678
27
0.1221
28
0.0704
29
0.0638
31
0.1523
32
0.0721
33
0.0690
34
0.1224
35
0.0702
36
0.1251
37
0.0660
38
0.0657
39
0.1213
40
0.1216
41
0.1222
42
0.1575
43
0.0697
44
0.1543
45
0.0665
46
0.1246
47
0.1210
48
0.0710
49
0.0704
50
0.0660
51
0.0678
53
0.0672
54
0.0624
55
0.0648
56
0.0717
57
0.0655
WD05-65
1
0.0651
2
0.1775
3
0.0650
4
0.0679
5
0.0683
207
Pb/235U±1σ
Measured ratios
206
Pb/238U±1σ
208
Pb/232Th±1σ
Th/U
207
Apparent ages (Ma)
Pb/206Pb±1σ 207Pb/235U±1σ 206Pb/238U±1σ
0.0033
0.0027
0.0026
0.0024
0.0034
0.0009
0.0022
0.0054
0.0021
0.0020
0.0021
0.0036
0.0027
0.0011
0.0033
0.0053
0.0019
0.0038
0.0008
0.0025
0.0018
0.0016
0.0027
0.0016
0.0015
0.0023
0.0025
0.0014
0.0019
0.0025
0.0040
0.0032
0.0012
0.0021
0.0014
0.0028
0.0022
0.0024
0.0014
0.0022
0.0016
0.0019
0.0025
0.0023
0.0014
0.0030
0.0030
0.0021
0.0040
0.0018
0.0028
0.0031
0.0041
0.0024
1.517
1.390
1.409
1.209
1.276
1.259
10.75
1.316
1.254
1.271
1.354
1.329
1.336
1.244
1.788
1.357
1.259
1.259
1.227
1.216
9.863
6.544
1.247
6.493
1.346
6.533
1.497
1.176
9.477
1.462
1.302
6.332
1.531
6.527
1.302
1.231
5.182
6.320
6.244
9.991
1.556
9.494
1.254
5.630
6.217
1.257
1.270
1.221
1.407
1.273
1.127
1.221
1.299
1.209
0.062
0.052
0.049
0.043
0.061
0.014
0.123
0.104
0.038
0.035
0.040
0.068
0.049
0.017
0.076
0.102
0.033
0.068
0.013
0.045
0.089
0.069
0.049
0.066
0.028
0.113
0.052
0.023
0.094
0.049
0.074
0.159
0.023
0.098
0.025
0.051
0.083
0.117
0.054
0.119
0.033
0.095
0.046
0.096
0.051
0.052
0.053
0.037
0.080
0.033
0.049
0.056
0.072
0.042
0.1428
0.1436
0.1434
0.1357
0.1357
0.1369
0.4863
0.1432
0.1353
0.1347
0.1428
0.1419
0.1362
0.1286
0.1760
0.1429
0.1330
0.1360
0.1367
0.1350
0.4612
0.3791
0.1369
0.3789
0.1441
0.3881
0.1541
0.1337
0.4515
0.1471
0.1368
0.3752
0.1581
0.3785
0.1431
0.1358
0.3100
0.3771
0.3706
0.4601
0.1619
0.4465
0.1368
0.3279
0.3726
0.1285
0.1309
0.1341
0.1505
0.1374
0.1311
0.1367
0.1315
0.1338
0.0020
0.0018
0.0017
0.0016
0.0021
0.0009
0.0040
0.0030
0.0014
0.0014
0.0015
0.0022
0.0017
0.0009
0.0025
0.0031
0.0013
0.0023
0.0009
0.0016
0.0033
0.0028
0.0017
0.0028
0.0012
0.0038
0.0019
0.0011
0.0034
0.0018
0.0024
0.0048
0.0012
0.0034
0.0012
0.0018
0.0028
0.0038
0.0026
0.0038
0.0014
0.0034
0.0017
0.0031
0.0025
0.0018
0.0018
0.0015
0.0027
0.0013
0.0018
0.0020
0.0023
0.0016
0.0437
0.0457
0.0442
0.0420
0.0426
0.0427
0.1462
0.0454
0.0448
0.0445
0.0447
0.0448
0.0439
0.0396
0.0595
0.0490
0.0431
0.0441
0.0435
0.0448
0.1371
0.1146
0.0418
0.1141
0.0475
0.1164
0.0545
0.0405
0.1323
0.0537
0.0455
0.1136
0.0513
0.1139
0.0458
0.0452
0.1020
0.1170
0.0762
0.1393
0.0528
0.1349
0.0434
0.0994
0.1147
0.0408
0.0454
0.0454
0.0473
0.0477
0.0434
0.0429
0.0438
0.0439
0.0008
0.0009
0.0007
0.0007
0.0009
0.0003
0.0019
0.0013
0.0008
0.0006
0.0006
0.0008
0.0009
0.0003
0.0011
0.0015
0.0005
0.0010
0.0003
0.0008
0.0011
0.0010
0.0008
0.0011
0.0005
0.0012
0.0014
0.0004
0.0015
0.0012
0.0008
0.0018
0.0006
0.0013
0.0005
0.0010
0.0016
0.0016
0.0009
0.0021
0.0009
0.0014
0.0007
0.0012
0.0011
0.0009
0.0008
0.0007
0.0011
0.0008
0.0009
0.0010
0.0011
0.0006
1.635
0.977
1.565
0.992
1.288
0.879
0.435
1.446
0.658
1.173
1.483
2.047
0.806
2.684
1.457
1.170
1.627
1.697
1.136
1.024
0.799
0.774
1.071
0.578
0.908
1.834
0.462
1.331
0.382
0.511
2.299
1.357
0.597
0.972
0.957
0.802
0.446
0.956
0.274
0.344
0.425
0.548
1.171
1.143
0.249
0.980
1.274
1.050
1.526
0.695
0.940
1.022
1.093
1.632
1123
934
965
761
874
828
2458
827
844
880
891
865
962
932
1033
895
889
843
778
785
2403
2032
808
2019
861
1987
941
736
2371
989
899
1992
935
2030
807
798
1975
1979
1989
2429
921
2394
822
2022
1971
956
939
807
862
843
687
768
977
791
82
78
72
76
100
28
23
160
65
60
63
106
77
32
87
151
56
112
27
78
20
23
83
22
45
33
72
45
21
70
116
46
35
30
44
87
32
35
20
24
46
21
78
33
20
85
86
66
117
56
94
97
112
75
0.0009
0.0022
0.0015
0.0020
0.0016
1.193
12.34
1.189
1.340
1.265
0.013
0.120
0.025
0.037
0.027
0.1330
0.5040
0.1327
0.1431
0.1342
0.0009
0.0038
0.0011
0.0014
0.0011
0.0411
0.1407
0.0413
0.0451
0.0401
0.0007
0.0014
0.0006
0.0007
0.0005
0.072
0.594
0.470
0.811
0.828
776
2630
774
865
879
28
20
48
60
47
860
865
864
820
820
827
2555
862
818
815
861
856
823
780
1045
861
805
822
826
816
2445
2072
827
2071
868
2114
924
809
2402
885
827
2054
946
2069
862
821
1741
2063
2032
2440
967
2380
826
1828
2042
779
793
811
904
830
794
826
796
810
11
10
10
9
12
5
17
17
8
8
9
12
9
5
14
17
7
13
5
9
15
13
10
13
7
18
10
6
15
10
13
22
7
16
7
10
14
18
12
17
8
15
9
15
12
10
10
8
15
8
10
11
13
9
937
885
893
805
835
828
2501
853
825
833
869
858
862
821
1041
871
828
828
813
808
2422
2052
822
2045
866
2050
929
789
2385
915
847
2023
943
2050
847
815
1850
2021
2011
2434
953
2387
825
1921
2007
827
832
810
892
834
766
810
845
805
25
22
21
20
27
6
11
46
17
16
17
30
21
8
28
44
15
31
6
20
8
9
22
9
12
15
21
11
9
20
33
22
9
13
11
23
14
16
8
11
13
9
21
15
7
23
23
17
34
15
23
26
32
19
805
5
797
6
2631
16
2630
9
803
6
796
12
862
8
863
16
812
6
830
12
(To be continued on the next page)
2450
LING WenLi, et al.
Chinese Sci Bull
(Continued)
No.
Measured ratios
Apparent ages (Ma)
7
8
Pb/206Pb±1σ
0.0655
0.0010
0.0666
0.0014
Pb/235U±1σ
1.170
0.015
1.249
0.024
Pb/238U±1σ
0.1296
0.0009
0.1360
0.0011
Pb/232Th±1σ
0.0391
0.0003
0.0399
0.0004
Th/U
1.543
0.922
207
207
206
208
Pb/206Pb±1σ
790
32
826
43
207
Pb/235U±1σ
786
5
822
6
207
Pb/238U±1σ
787
7
823
11
206
9
0.0676
0.0012
1.270
0.019
0.1363
0.0010
0.0416
0.0004
0.857
856
35
824
6
832
9
10
0.0678
0.0011
1.278
0.018
0.1366
0.0010
0.0430
0.0004
0.905
863
33
826
6
836
8
11
0.0660
0.0010
1.206
0.016
0.1326
0.0009
0.0387
0.0003
1.167
806
32
803
5
803
7
12
0.0675
0.0009
1.259
0.014
0.1354
0.0009
0.0425
0.0003
1.116
852
29
818
5
828
6
13
0.0641
0.0009
1.196
0.013
0.1354
0.0009
0.0409
0.0003
0.830
744
29
819
5
799
6
14
0.0642
0.0010
1.195
0.015
0.1351
0.0009
0.0424
0.0004
0.667
747
32
817
5
799
7
15
0.0664
0.0014
1.233
0.023
0.1346
0.0011
0.0423
0.0004
0.870
820
43
814
6
816
11
16
0.0663
0.0015
1.232
0.026
0.1348
0.0011
0.0433
0.0005
0.835
816
47
815
6
815
12
17
0.0634
0.0014
1.170
0.024
0.1339
0.0011
0.0397
0.0004
1.768
721
46
810
6
787
11
18
0.0660
0.0008
1.251
0.011
0.1376
0.0009
0.0414
0.0003
0.298
806
24
831
5
824
5
19
0.0677
0.0014
1.239
0.024
0.1329
0.0011
0.0416
0.0004
0.885
858
43
804
6
819
11
20
0.0664
0.0015
1.259
0.025
0.1376
0.0011
0.0417
0.0005
0.608
818
45
831
6
827
11
21
0.0677
0.0010
1.225
0.014
0.1313
0.0009
0.0453
0.0004
0.646
858
29
795
5
812
6
22
0.0648
0.0015
1.154
0.025
0.1292
0.0011
0.0379
0.0004
0.940
768
48
783
6
779
12
23
0.1219
0.0028
6.128
0.133
0.3645
0.0041
0.1186
0.0019
0.741
1985
41
2003
19
1994
19
24
0.0667
0.0009
1.237
0.012
0.1344
0.0009
0.0413
0.0003
1.202
830
26
813
5
817
6
25
0.0657
0.0020
1.227
0.035
0.1355
0.0013
0.0425
0.0006
1.038
796
62
819
7
813
16
26
0.1239
0.0014
6.298
0.048
0.3686
0.0024
0.1035
0.0006
1.337
2013
19
2023
11
2018
7
27
0.0684
0.0008
1.245
0.012
0.1322
0.0009
0.0427
0.0004
0.564
879
25
800
5
821
5
28
0.0689
0.0018
1.290
0.031
0.1358
0.0012
0.0449
0.0007
0.524
896
52
821
7
842
14
29
0.0687
0.0019
1.302
0.034
0.1375
0.0013
0.0394
0.0005
0.970
890
56
830
7
847
15
30
0.0679
0.0014
1.251
0.024
0.1336
0.0011
0.0408
0.0004
0.936
866
43
808
6
824
11
31
0.0688
0.0025
1.399
0.048
0.1474
0.0017
0.0467
0.0008
1.027
893
72
886
10
888
20
32
0.1223
0.0018
6.184
0.079
0.3667
0.0029
0.1052
0.0010
1.121
1990
26
2014
14
2002
11
33
0.0650
0.0008
1.196
0.012
0.1334
0.0009
0.0396
0.0002
1.834
775
26
807
5
799
5
34
0.0680
0.0026
1.261
0.045
0.1346
0.0016
0.0417
0.0007
1.031
868
76
814
9
828
20
35
0.0676
0.0014
1.332
0.026
0.1428
0.0012
0.0439
0.0006
0.614
857
44
861
7
860
11
36
0.0681
0.0019
1.209
0.031
0.1288
0.0012
0.0399
0.0005
1.067
871
56
781
7
805
14
37
0.0703
0.0020
1.310
0.034
0.1351
0.0013
0.0415
0.0006
0.832
938
56
817
7
850
15
38
0.0687
0.0010
1.289
0.015
0.1361
0.0009
0.0424
0.0004
0.545
889
29
823
5
841
7
39
0.0681
0.0015
1.344
0.026
0.1431
0.0012
0.0446
0.0005
0.823
872
44
862
7
865
11
40
0.0653
0.0018
1.205
0.031
0.1339
0.0012
0.0429
0.0009
0.362
783
56
810
7
803
14
41
0.0645
0.0011
1.168
0.018
0.1314
0.0010
0.0392
0.0003
0.947
757
36
796
5
786
8
42
0.0651
0.0015
1.177
0.025
0.1312
0.0011
0.0420
0.0005
1.023
777
48
795
6
790
12
43
0.0669
0.0007
1.377
0.010
0.1492
0.0009
0.0446
0.0003
1.153
836
23
896
5
879
4
44
0.0645
0.0016
1.139
0.026
0.1280
0.0011
0.0379
0.0006
0.473
758
52
777
6
772
13
45
0.0658
0.0012
1.210
0.019
0.1334
0.0010
0.0442
0.0003
1.513
799
37
808
6
805
9
46
0.0673
0.0009
1.329
0.013
0.1433
0.0009
0.0441
0.0003
0.741
847
26
863
5
859
6
47
0.0647
0.0009
1.231
0.015
0.1380
0.0009
0.0425
0.0003
0.775
765
30
833
5
815
7
48
0.0646
0.0014
1.196
0.024
0.1344
0.0011
0.0415
0.0010
0.216
761
45
813
6
799
11
49
0.0648
0.0021
1.215
0.036
0.1361
0.0014
0.0414
0.0006
1.125
767
65
823
8
808
17
50
0.0648
0.0013
1.202
0.022
0.1346
0.0011
0.0413
0.0004
1.100
767
42
814
6
802
10
51
0.0688
0.0011
1.358
0.019
0.1431
0.0010
0.0455
0.0005
0.390
894
34
862
6
871
8
52
0.0652
0.0013
1.189
0.022
0.1323
0.0011
0.0403
0.0005
0.683
781
42
801
6
796
10
53
0.0655
0.0012
1.227
0.020
0.1358
0.0010
0.0423
0.0004
1.073
790
39
821
6
813
9
54
0.0702
0.0039
1.283
0.068
0.1326
0.0022
0.0429
0.0010
1.302
933
109
803
12
838
30
56
0.0674
0.0014
1.256
0.024
0.1352
0.0011
0.0410
0.0005
0.708
849
43
817
6
826
11
LING WenLi, et al.
Chinese Sci Bull
2451
(Continued)
Measured ratios
No.
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
Apparent ages (Ma)
208
Pb/232Th±1σ
Th/U
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
57
0.0650
0.0014
1.202
0.023
0.1340
0.0011
0.0403
0.0004
1.189
776
44
811
6
801
11
59
0.0666
0.0015
1.205
0.025
0.1313
0.0011
0.0390
0.0006
0.378
824
46
795
6
803
11
60
0.0684
0.0016
1.276
0.028
0.1353
0.0012
0.0430
0.0007
0.425
880
49
818
7
835
13
61
0.0701
0.0024
1.264
0.041
0.1309
0.0015
0.0427
0.0008
0.752
931
68
793
8
830
18
62
0.0679
0.0009
1.373
0.015
0.1467
0.0010
0.0452
0.0004
0.559
865
27
882
6
877
6
63
0.0659
0.0011
1.250
0.019
0.1375
0.0010
0.0428
0.0004
0.513
805
36
831
6
824
9
64
0.0644
0.0016
1.156
0.027
0.1301
0.0012
0.0403
0.0005
0.847
756
53
789
7
780
13
65
0.0663
0.0012
1.274
0.020
0.1393
0.0010
0.0420
0.0004
0.797
817
36
841
6
834
9
66
0.0659
0.0014
1.196
0.023
0.1316
0.0011
0.0411
0.0004
0.970
804
44
797
6
799
11
67
0.0666
0.0011
1.235
0.017
0.1345
0.0010
0.0424
0.0004
0.537
825
34
813
5
817
8
68
0.0695
0.0017
1.442
0.033
0.1504
0.0014
0.0505
0.0007
0.722
914
50
903
8
906
14
WD06-14
1
0.0655
0.0022
0.896
0.029
0.0993
0.0011
0.0300
0.0006
0.545
789
70
610
7
650
16
2
0.0633
0.0025
0.811
0.030
0.0929
0.0011
0.0269
0.0007
0.491
718
80
573
7
603
17
3
0.0655
0.0015
0.884
0.019
0.0979
0.0008
0.0275
0.0003
0.903
791
47
602
5
643
10
4
0.0634
0.0018
0.976
0.025
0.1116
0.0011
0.0313
0.0005
0.561
722
58
682
6
692
13
5
0.0629
0.0025
0.932
0.036
0.1074
0.0013
0.0291
0.0007
0.610
706
83
657
8
669
19
6
0.0623
0.0027
1.027
0.043
0.1196
0.0016
0.0343
0.0010
0.550
684
89
728
9
718
21
7
0.0622
0.0044
0.949
0.065
0.1106
0.0023
0.0319
0.0015
0.447
682
144
676
13
677
34
8
0.0676
0.0026
0.966
0.035
0.1036
0.0013
0.0318
0.0007
0.568
857
77
635
7
686
18
10
0.0658
0.0019
0.933
0.025
0.1027
0.0010
0.0278
0.0004
0.993
801
58
631
6
669
13
11
0.0662
0.0031
1.028
0.046
0.1127
0.0016
0.0327
0.0009
0.552
812
94
688
9
718
23
12
0.0679
0.0044
1.339
0.085
0.1429
0.0028
0.0427
0.0015
0.894
867
129
861
16
863
37
14
0.0661
0.0027
0.985
0.038
0.1082
0.0014
0.0295
0.0007
0.672
808
82
662
8
696
20
15
0.0664
0.0037
0.915
0.049
0.1000
0.0017
0.0333
0.0012
0.462
817
112
615
10
660
26
16
0.0640
0.0022
0.877
0.028
0.0995
0.0011
0.0277
0.0005
0.715
740
70
611
6
640
15
18
0.0640
0.0022
1.037
0.034
0.1174
0.0013
0.0328
0.0007
0.639
742
72
716
8
722
17
19
0.0646
0.0021
1.018
0.032
0.1143
0.0012
0.0308
0.0006
0.781
761
67
698
7
713
16
20
0.0628
0.0021
0.928
0.030
0.1073
0.0012
0.0300
0.0006
0.699
700
70
657
7
667
16
22
0.0615
0.0013
0.687
0.013
0.0811
0.0007
0.0186
0.0002
1.295
656
45
503
4
531
8
24
0.0670
0.0021
0.961
0.028
0.1040
0.0011
0.0282
0.0005
0.712
839
64
638
6
684
15
26
0.0645
0.0013
0.924
0.016
0.1038
0.0008
0.0282
0.0003
1.020
759
41
637
5
664
9
27
0.0648
0.0025
1.026
0.037
0.1148
0.0014
0.0313
0.0008
0.544
769
78
701
8
717
19
28
0.0645
0.0033
1.040
0.052
0.1169
0.0018
0.0318
0.0010
0.527
758
105
713
10
724
26
30
0.0663
0.0027
0.998
0.039
0.1092
0.0014
0.0296
0.0007
0.714
815
83
668
8
703
20
32
0.0672
0.0023
0.980
0.032
0.1059
0.0012
0.0306
0.0007
0.565
842
71
649
7
694
17
33
0.0629
0.0016
1.042
0.024
0.1202
0.0011
0.0337
0.0005
0.658
705
52
732
6
725
12
35
0.0626
0.0018
1.033
0.028
0.1198
0.0012
0.0323
0.0005
1.015
694
60
729
7
721
14
36
0.0626
0.0021
0.959
0.031
0.1112
0.0012
0.0316
0.0006
0.618
693
71
680
7
683
16
37
0.1173
0.0036
5.148
0.150
0.3184
0.0045
0.0849
0.0022
0.464
1915
54
1782
22
1844
25
38
0.0676
0.0025
0.942
0.033
0.1010
0.0012
0.0301
0.0007
0.513
856
74
621
7
674
17
39
0.0678
0.0027
0.928
0.035
0.0993
0.0012
0.0279
0.0006
0.833
863
80
610
7
667
19
40
0.0634
0.0032
0.982
0.048
0.1124
0.0016
0.0320
0.0008
0.943
721
103
687
10
695
24
43
0.0645
0.0015
0.895
0.020
0.1006
0.0009
0.0265
0.0003
0.752
758
49
618
5
649
11
44
0.0652
0.0018
0.975
0.025
0.1084
0.0010
0.0300
0.0005
0.556
781
57
664
6
691
13
45
0.0705
0.0032
0.936
0.040
0.0963
0.0014
0.0291
0.0008
0.641
942
89
593
8
671
21
46
0.0648
0.0021
0.858
0.027
0.0960
0.0010
0.0269
0.0005
0.590
767
68
591
6
629
15
47
0.0647
0.0019
0.649
0.018
0.0727
0.0007
0.0175
0.0002
1.324
764
61
453
4
508
11
49
0.0654
0.0029
1.028
0.044
0.1140
0.0016
0.0320
0.0008
0.589
787
91
696
9
718
22
2452
LING WenLi, et al.
Chinese Sci Bull
(Continued)
Measured ratios
No.
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
Apparent ages (Ma)
208
Pb/232Th±1σ
Th/U
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
51
0.0627
0.0019
0.849
0.025
0.0983
0.0010
0.0273
0.0005
0.576
696
64
605
6
624
13
53
0.0674
0.0046
1.000
0.066
0.1076
0.0021
0.0352
0.0014
0.562
851
136
659
12
704
34
WD05-S1
1
0.0611
0.0016
0.792
0.019
0.0940
0.0009
0.0247
0.0003
1.957
643
55
579
5
592
11
2
0.0634
0.0032
1.073
0.053
0.1228
0.0018
0.0375
0.0009
1.066
720
104
747
10
740
26
3
0.0647
0.0052
0.959
0.075
0.1075
0.0024
0.0336
0.0011
1.292
764
160
658
14
683
39
4
0.0646
0.0031
1.097
0.051
0.1232
0.0017
0.0424
0.0005
3.027
761
98
749
10
752
25
5
0.0642
0.0031
0.967
0.045
0.1094
0.0016
0.0340
0.0008
1.082
747
99
669
9
687
23
6
0.0658
0.0042
0.984
0.061
0.1085
0.0020
0.0327
0.0013
0.655
800
128
664
11
696
31
7
0.0619
0.0013
0.958
0.018
0.1122
0.0009
0.0350
0.0005
0.487
672
44
686
5
682
10
8
0.0659
0.0028
1.104
0.046
0.1216
0.0016
0.0374
0.0008
0.987
802
88
740
9
755
22
9
0.0708
0.0028
0.857
0.033
0.0878
0.0011
0.0350
0.0007
0.771
952
80
542
7
628
18
10
0.0616
0.0020
1.052
0.033
0.1239
0.0013
0.0376
0.0007
0.701
660
70
753
8
730
17
100
0.0692
0.0025
0.971
0.034
0.1018
0.0012
0.0343
0.0006
0.939
904
73
625
7
689
17
101
0.0650
0.0018
1.108
0.028
0.1236
0.0012
0.0396
0.0006
0.677
774
56
751
7
757
14
102
0.0648
0.0021
1.105
0.034
0.1237
0.0013
0.0399
0.0008
0.589
768
66
752
8
756
16
103
0.0633
0.0016
1.084
0.025
0.1241
0.0011
0.0391
0.0006
0.743
720
52
754
6
746
12
104
0.0634
0.0037
0.977
0.055
0.1117
0.0018
0.0348
0.0013
0.557
722
118
683
10
692
28
105
0.0633
0.0030
1.083
0.051
0.1242
0.0017
0.0415
0.0008
1.431
717
99
755
10
745
25
11
0.0633
0.0023
0.987
0.034
0.1131
0.0013
0.0339
0.0005
1.576
720
74
691
7
697
17
12
0.0638
0.0050
1.050
0.081
0.1194
0.0026
0.0358
0.0012
1.313
735
159
727
15
729
40
13
0.0640
0.0020
1.076
0.031
0.1219
0.0013
0.0369
0.0007
0.925
743
64
741
7
742
15
14
0.0632
0.0017
1.082
0.028
0.1242
0.0012
0.0391
0.0007
0.447
714
57
755
7
744
14
15
0.0632
0.0019
0.992
0.028
0.1138
0.0011
0.0368
0.0005
1.803
715
62
695
7
700
14
16
0.0633
0.0057
0.971
0.085
0.1112
0.0026
0.0379
0.0021
0.517
720
179
680
15
689
44
17
0.0622
0.0023
0.961
0.035
0.1120
0.0013
0.0315
0.0004
2.402
681
78
685
8
684
18
18
0.0642
0.0011
1.073
0.017
0.1213
0.0009
0.0319
0.0003
0.676
747
37
738
5
740
8
19
0.0615
0.0056
0.936
0.082
0.1103
0.0027
0.0309
0.0016
0.900
658
182
675
16
671
43
20
0.0637
0.0024
1.075
0.039
0.1224
0.0015
0.0370
0.0006
1.599
732
79
744
8
741
19
21
0.0643
0.0014
1.108
0.021
0.1250
0.0010
0.0343
0.0003
1.686
751
44
759
6
757
10
22
0.0642
0.0020
1.098
0.033
0.1241
0.0013
0.0335
0.0006
1.239
748
66
754
8
753
16
23
0.0629
0.0011
1.087
0.017
0.1253
0.0010
0.0359
0.0005
0.467
706
37
761
6
747
8
24
0.0608
0.0015
0.794
0.018
0.0948
0.0008
0.0250
0.0003
1.713
631
51
584
5
594
10
26
0.0642
0.0029
1.088
0.047
0.1228
0.0017
0.0328
0.0009
0.675
750
92
747
10
748
23
27
0.0656
0.0037
0.994
0.054
0.1099
0.0018
0.0340
0.0009
1.187
794
113
672
10
701
27
28
0.0658
0.0024
1.110
0.039
0.1223
0.0014
0.0392
0.0006
1.550
800
76
744
8
758
19
29
0.0641
0.0027
1.084
0.044
0.1227
0.0016
0.0376
0.0008
1.051
745
87
746
9
746
21
30
0.0652
0.0020
1.104
0.033
0.1227
0.0013
0.0381
0.0006
0.978
781
64
746
7
755
16
32
0.0643
0.0018
0.936
0.025
0.1056
0.0010
0.0345
0.0004
1.610
751
59
647
6
671
13
33
0.0664
0.0026
1.233
0.046
0.1346
0.0017
0.0408
0.0008
0.858
820
80
814
10
816
21
34
0.0629
0.0012
1.075
0.019
0.1239
0.0010
0.0402
0.0004
0.842
705
40
753
6
741
9
36
0.0612
0.0019
1.012
0.030
0.1199
0.0012
0.0380
0.0006
1.119
647
65
730
7
710
15
37
0.0643
0.0018
1.088
0.028
0.1228
0.0012
0.0392
0.0006
0.642
751
57
747
7
748
14
38
0.0643
0.0025
1.098
0.041
0.1238
0.0015
0.0379
0.0007
1.672
751
79
753
9
752
20
39
0.0632
0.0018
1.027
0.028
0.1178
0.0012
0.0352
0.0005
0.952
716
60
718
7
717
14
40
0.0645
0.0026
1.068
0.041
0.1202
0.0015
0.0375
0.0007
1.191
757
81
732
9
738
20
41
0.0615
0.0027
0.805
0.034
0.0950
0.0012
0.0303
0.0007
0.810
655
91
585
7
599
19
42
0.0665
0.0023
1.207
0.041
0.1316
0.0015
0.0397
0.0007
1.126
822
72
797
9
804
19
43
0.0637
0.0020
1.069
0.032
0.1217
0.0013
0.0357
0.0006
1.155
733
66
740
7
738
16
LING WenLi, et al.
Chinese Sci Bull
2453
(Continued)
No.
Measured ratios
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
Apparent ages (Ma)
208
Pb/232Th±1σ
Th/U
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
44
0.0666
0.0017
1.027
0.025
0.1120
0.0010
0.0359
0.0005
1.128
824
53
684
6
718
13
45
0.0681
0.0020
1.149
0.032
0.1225
0.0012
0.0360
0.0005
1.455
870
59
745
7
777
15
46
0.0645
0.0016
1.112
0.026
0.1250
0.0011
0.0380
0.0004
1.435
758
52
759
7
759
13
47
0.0654
0.0026
1.160
0.044
0.1286
0.0016
0.0409
0.0007
1.534
788
81
780
9
782
21
48
0.0661
0.0021
1.201
0.036
0.1317
0.0014
0.0411
0.0007
0.985
811
65
798
8
801
17
49
0.0634
0.0034
1.039
0.055
0.1188
0.0019
0.0389
0.0011
0.802
723
111
724
11
724
27
51
0.0674
0.0035
1.210
0.060
0.1301
0.0020
0.0414
0.0011
0.857
852
104
789
11
805
28
52
0.0665
0.0034
1.034
0.052
0.1129
0.0017
0.0384
0.0011
0.764
821
104
690
10
721
26
54
0.0650
0.0018
1.108
0.030
0.1236
0.0012
0.0393
0.0007
0.692
776
58
751
7
757
14
55
0.0650
0.0015
1.181
0.026
0.1317
0.0012
0.0415
0.0004
2.683
776
49
798
7
792
12
56
0.1059
0.0016
4.476
0.057
0.3066
0.0024
0.0892
0.0008
0.956
1730
27
1724
12
1727
11
57
0.1042
0.0015
4.474
0.055
0.3115
0.0024
0.0937
0.0011
0.498
1700
27
1748
12
1726
10
58
0.0655
0.0024
1.178
0.042
0.1306
0.0016
0.0409
0.0009
0.725
789
76
791
9
791
20
59
0.0644
0.0020
1.100
0.033
0.1238
0.0013
0.0393
0.0007
0.794
755
64
753
7
753
16
60
0.0647
0.0016
1.103
0.025
0.1237
0.0011
0.0388
0.0005
0.961
763
51
752
6
755
12
61
0.0677
0.0019
1.348
0.036
0.1444
0.0014
0.0447
0.0010
0.397
860
57
869
8
867
15
62
0.0645
0.0016
1.101
0.026
0.1239
0.0011
0.0393
0.0005
0.950
757
52
753
6
754
12
63
0.0643
0.0020
1.069
0.032
0.1207
0.0012
0.0364
0.0005
1.488
750
64
735
7
738
16
64
0.0673
0.0030
1.204
0.053
0.1297
0.0018
0.0414
0.0008
1.396
848
91
786
10
802
24
65
0.0645
0.0027
1.103
0.044
0.1241
0.0016
0.0392
0.0006
1.675
757
85
754
9
755
21
66
0.0635
0.0044
0.975
0.066
0.1114
0.0022
0.0380
0.0010
1.435
724
140
681
12
691
34
67
0.0658
0.0024
1.199
0.042
0.1321
0.0015
0.0421
0.0009
0.632
801
74
800
9
800
19
68
0.0638
0.0017
1.054
0.027
0.1200
0.0011
0.0388
0.0006
0.600
733
56
730
6
731
13
69
0.0642
0.0025
1.092
0.041
0.1234
0.0015
0.0396
0.0010
0.514
747
80
750
8
749
20
70
0.0629
0.0026
1.079
0.043
0.1244
0.0015
0.0409
0.0007
1.197
704
86
756
9
743
21
71
0.0655
0.0028
1.114
0.045
0.1234
0.0016
0.0385
0.0009
0.915
791
86
750
9
760
22
72
0.0656
0.0017
1.106
0.026
0.1223
0.0011
0.0388
0.0006
0.719
793
52
744
6
756
13
73
0.0658
0.0015
1.044
0.022
0.1151
0.0010
0.0379
0.0005
0.813
801
47
702
6
726
11
74
0.0671
0.0031
1.197
0.053
0.1294
0.0018
0.0409
0.0010
0.729
840
92
784
10
799
24
76
0.0662
0.0017
1.183
0.029
0.1296
0.0012
0.0409
0.0005
1.043
813
54
786
7
793
14
77
0.0694
0.0018
0.916
0.022
0.0958
0.0009
0.0384
0.0008
0.328
910
51
590
5
660
12
78
0.0626
0.0045
1.053
0.073
0.1219
0.0024
0.0397
0.0010
1.576
696
145
742
14
730
36
80
0.0623
0.0018
0.935
0.025
0.1089
0.0011
0.0371
0.0005
1.034
684
59
666
6
670
13
81
0.0686
0.0032
1.030
0.046
0.1090
0.0016
0.0367
0.0010
0.667
886
94
667
9
719
23
82
0.0604
0.0015
1.030
0.023
0.1237
0.0011
0.0396
0.0005
0.818
618
51
752
6
719
12
83
0.0629
0.0012
1.064
0.017
0.1226
0.0010
0.0378
0.0004
0.834
706
38
746
6
736
9
84
0.0657
0.0014
1.116
0.023
0.1233
0.0011
0.0401
0.0005
0.739
796
45
749
6
761
11
85
0.0603
0.0012
0.928
0.017
0.1118
0.0009
0.0298
0.0003
0.992
613
43
683
5
667
9
86
0.0639
0.0062
1.069
0.101
0.1213
0.0033
0.0392
0.0016
1.226
740
193
738
19
738
50
87
0.0622
0.0014
1.062
0.023
0.1238
0.0011
0.0385
0.0004
2.086
681
48
753
6
735
11
88
0.0625
0.0048
0.956
0.071
0.1108
0.0023
0.0347
0.0015
0.581
692
155
678
13
681
37
89
0.0645
0.0019
1.106
0.031
0.1243
0.0013
0.0406
0.0007
0.835
759
60
755
7
756
15
90
0.0630
0.0015
1.085
0.025
0.1249
0.0011
0.0395
0.0006
0.646
707
51
759
6
746
12
91
0.0637
0.0024
1.100
0.039
0.1254
0.0015
0.0392
0.0009
0.604
730
76
761
8
753
19
92
0.0655
0.0036
1.178
0.063
0.1304
0.0020
0.0407
0.0007
2.717
792
111
790
11
790
29
93
0.0627
0.0010
1.073
0.014
0.1242
0.0009
0.0391
0.0003
1.077
697
33
755
5
740
7
94
0.0631
0.0037
1.038
0.059
0.1193
0.0020
0.0370
0.0010
1.091
711
120
727
12
723
30
95
0.0673
0.0033
1.220
0.058
0.1314
0.0020
0.0426
0.0011
0.800
848
99
796
11
810
27
96
0.0663
0.0011
1.112
0.016
0.1217
0.0009
0.0396
0.0005
0.289
816
34
740
5
759
8
2454
LING WenLi, et al.
Chinese Sci Bull
(Continued)
Measured ratios
No.
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
Apparent ages (Ma)
208
Pb/232Th±1σ
Th/U
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
97
0.0646
0.0023
1.101
0.038
0.1236
0.0014
0.0362
0.0008
0.600
763
74
751
8
754
18
98
0.0644
0.0032
0.962
0.046
0.1084
0.0016
0.0358
0.0010
0.669
755
100
663
9
685
24
99
0.0627
0.0017
1.069
0.028
0.1237
0.0012
0.0407
0.0005
1.135
697
58
752
7
738
14
WD05-S2
1
0.1224
0.0026
6.111
0.121
0.3634
0.0041
0.1003
0.0017
0.665
1992
37
1998
19
1992
17
2
0.0668
0.0015
1.261
0.025
0.1374
0.0012
0.0419
0.0006
0.570
832
45
830
7
829
11
3
0.0672
0.0010
1.277
0.015
0.1383
0.0010
0.0399
0.0004
0.309
845
30
835
5
835
7
4
0.0675
0.0030
1.264
0.055
0.1364
0.0020
0.0412
0.0012
0.576
852
90
824
11
830
25
5
0.1232
0.0044
6.252
0.222
0.3695
0.0069
0.0996
0.0027
0.835
2003
62
2027
32
2012
31
6
0.1539
0.0021
9.430
0.106
0.4461
0.0037
0.1238
0.0015
0.450
2390
23
2378
16
2381
10
7
0.1233
0.0024
6.127
0.109
0.3619
0.0038
0.0990
0.0014
0.792
2004
34
1991
18
1994
16
8
0.0666
0.0023
1.219
0.040
0.1333
0.0016
0.0424
0.0007
1.052
825
70
807
9
810
18
9
0.1222
0.0018
6.055
0.078
0.3608
0.0030
0.1017
0.0008
1.887
1989
26
1986
14
1984
11
10
0.1235
0.0016
6.185
0.062
0.3646
0.0027
0.0998
0.0015
0.162
2007
22
2004
13
2002
9
11
0.1591
0.0022
9.424
0.114
0.4312
0.0037
0.1159
0.0016
0.432
2446
24
2311
17
2380
11
12
0.1209
0.0013
6.203
0.044
0.3736
0.0024
0.1000
0.0010
0.116
1969
19
2046
11
2005
6
13
0.1244
0.0028
6.305
0.135
0.3691
0.0045
0.1040
0.0017
0.875
2020
39
2025
21
2019
19
14
0.0667
0.0022
1.219
0.039
0.1331
0.0015
0.0388
0.0006
1.102
828
68
805
9
809
18
15
0.1256
0.0029
6.416
0.144
0.3720
0.0047
0.1080
0.0019
0.778
2037
41
2039
22
2035
20
16
0.0659
0.0009
1.238
0.014
0.1368
0.0009
0.0410
0.0003
0.878
803
28
826
5
818
6
17
0.0667
0.0013
1.221
0.022
0.1332
0.0011
0.0419
0.0005
0.396
828
40
806
6
810
10
18
0.0697
0.0013
1.444
0.024
0.1509
0.0012
0.0479
0.0005
0.587
919
37
906
7
908
10
20
0.0654
0.0035
1.146
0.060
0.1276
0.0021
0.0434
0.0011
0.878
786
109
774
12
775
29
21
0.0670
0.0034
1.262
0.062
0.1372
0.0022
0.0400
0.0009
1.095
836
101
829
13
829
28
22
0.1259
0.0049
6.426
0.254
0.3714
0.0078
0.1045
0.0030
0.951
2042
68
2036
37
2036
35
23
0.0666
0.0017
1.180
0.029
0.1291
0.0012
0.0396
0.0006
0.761
824
53
783
7
791
13
24
0.1546
0.0039
9.469
0.239
0.4458
0.0070
0.1141
0.0034
0.357
2397
42
2376
31
2385
23
25
0.0678
0.0011
1.287
0.019
0.1381
0.0010
0.0414
0.0005
0.406
862
34
834
6
840
8
26
0.0672
0.0031
1.262
0.056
0.1366
0.0021
0.0412
0.0009
0.924
845
92
825
12
829
25
27
0.1228
0.0019
6.192
0.087
0.3670
0.0033
0.1054
0.0012
0.807
1997
28
2015
15
2003
12
28
0.0665
0.0019
1.217
0.034
0.1332
0.0014
0.0418
0.0006
0.761
822
60
806
8
809
15
29
0.0654
0.0027
1.144
0.045
0.1274
0.0017
0.0520
0.0012
0.696
786
84
773
10
775
22
30
0.0660
0.0017
1.204
0.029
0.1327
0.0013
0.0412
0.0005
0.820
807
52
803
7
802
13
31
0.1034
0.0028
4.260
0.112
0.2998
0.0039
0.0859
0.0018
0.339
1686
49
1690
19
1686
22
32
0.0710
0.0015
1.504
0.030
0.1540
0.0014
0.0467
0.0006
0.614
958
44
924
8
932
12
33
0.0686
0.0024
1.282
0.044
0.1359
0.0016
0.0418
0.0006
1.546
888
72
822
9
838
19
34
0.1232
0.0030
6.168
0.147
0.3642
0.0048
0.1035
0.0019
0.773
2003
43
2002
23
2000
21
35
0.1247
0.0039
6.321
0.196
0.3687
0.0061
0.1068
0.0028
0.677
2025
54
2024
29
2021
27
36
0.1239
0.0032
6.241
0.156
0.3664
0.0051
0.1046
0.0019
0.880
2013
45
2013
24
2010
22
37
0.0658
0.0013
1.220
0.021
0.1350
0.0011
0.0425
0.0004
0.966
799
40
817
6
810
10
38
0.1277
0.0021
6.596
0.100
0.3757
0.0036
0.1117
0.0014
0.743
2067
29
2056
17
2059
13
39
0.0679
0.0018
1.255
0.032
0.1344
0.0013
0.0406
0.0005
1.145
867
55
813
8
826
14
40
0.0703
0.0029
1.497
0.061
0.1548
0.0022
0.0459
0.0010
0.959
938
83
928
12
929
25
41
0.0650
0.0031
1.163
0.054
0.1302
0.0020
0.0394
0.0010
0.566
774
97
789
11
783
25
42
0.0710
0.0018
1.557
0.037
0.1596
0.0016
0.0480
0.0007
0.626
957
51
954
9
953
15
43
0.0643
0.0013
1.153
0.021
0.1305
0.0011
0.0399
0.0003
1.482
752
43
791
6
779
10
44
0.0671
0.0020
1.226
0.035
0.1330
0.0014
0.0416
0.0006
1.223
839
61
805
8
813
16
45
0.1219
0.0037
6.029
0.179
0.3598
0.0057
0.0869
0.0020
0.867
1984
53
1981
27
1980
26
46
0.0685
0.0017
1.381
0.032
0.1465
0.0014
0.0441
0.0007
0.609
885
51
881
8
881
14
LING WenLi, et al.
Chinese Sci Bull
2455
(Continued)
No.
Measured ratios
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
Apparent ages (Ma)
208
Pb/232Th±1σ
Th/U
207
Pb/206Pb±1σ
207
Pb/235U±1σ
206
Pb/238U±1σ
47
0.0656
0.0010
1.162
0.015
0.1289
0.0009
0.0395
0.0004
0.474
792
32
782
5
783
7
48
0.0666
0.0014
1.172
0.022
0.1280
0.0011
0.0390
0.0004
1.418
825
42
777
6
788
10
49
0.0654
0.0008
1.191
0.010
0.1325
0.0009
0.0409
0.0003
0.495
787
24
802
5
796
5
50
0.0669
0.0025
1.230
0.044
0.1337
0.0017
0.0468
0.0009
0.718
835
75
809
10
814
20
51
0.0717
0.0025
1.603
0.055
0.1625
0.0021
0.0487
0.0011
0.588
978
71
971
11
971
21
52
0.1149
0.0014
5.305
0.050
0.3359
0.0024
0.0991
0.0008
0.499
1878
22
1867
11
1870
8
53
0.1211
0.0014
5.956
0.049
0.3577
0.0024
0.1084
0.0014
0.087
1972
20
1971
11
1969
7
55
0.0684
0.0010
1.399
0.016
0.1487
0.0010
0.0446
0.0004
0.659
881
28
894
6
888
7
17
56
0.0668
0.0021
1.250
0.038
0.1361
0.0015
0.0439
0.0008
0.586
832
65
823
9
824
57
0.0681
0.0010
1.389
0.017
0.1484
0.0010
0.0459
0.0004
0.409
870
29
892
6
884
7
58
0.0683
0.0013
1.270
0.022
0.1353
0.0011
0.0431
0.0006
0.444
877
39
818
6
832
10
59
0.0671
0.0016
1.230
0.027
0.1334
0.0012
0.0415
0.0005
0.760
840
48
807
7
815
12
60
0.0663
0.0011
1.238
0.018
0.1358
0.0010
0.0421
0.0004
0.788
816
34
821
6
818
8
61
0.0673
0.0019
1.253
0.034
0.1354
0.0014
0.0441
0.0007
0.733
846
58
818
8
825
15
62
0.0671
0.0033
1.236
0.059
0.1340
0.0021
0.0462
0.0013
0.661
840
99
811
12
817
27
63
0.0684
0.0033
1.285
0.060
0.1366
0.0022
0.0421
0.0008
1.396
879
96
826
12
839
27
64
0.0673
0.0014
1.256
0.025
0.1357
0.0012
0.0427
0.0006
0.467
847
44
820
7
826
11
65
0.0677
0.0016
1.276
0.029
0.1370
0.0013
0.0418
0.0005
0.973
860
50
828
7
835
13
66
0.0673
0.0009
1.367
0.015
0.1477
0.0010
0.0452
0.0004
0.601
846
28
888
6
875
7
67
0.0650
0.0014
1.215
0.024
0.1359
0.0012
0.0422
0.0004
1.299
774
45
821
7
807
11
68
0.0699
0.0034
1.486
0.070
0.1546
0.0025
0.0516
0.0016
0.514
926
96
926
14
925
29
69
0.0660
0.0015
1.227
0.026
0.1352
0.0012
0.0395
0.0007
0.348
805
47
818
7
813
12
70
0.0683
0.0035
1.268
0.063
0.1351
0.0023
0.0450
0.0009
1.382
876
102
817
13
832
28
71
0.0663
0.0021
1.237
0.037
0.1356
0.0015
0.0423
0.0007
0.807
816
65
820
8
818
17
72
0.1247
0.0032
6.308
0.158
0.3677
0.0051
0.1067
0.0020
0.836
2024
45
2019
24
2020
22
73
0.1126
0.0015
5.113
0.055
0.3301
0.0025
0.0977
0.0009
0.677
1842
24
1839
12
1838
9
75
0.0661
0.0024
1.216
0.043
0.1338
0.0016
0.0402
0.0006
1.587
809
74
809
9
808
20
78
0.0671
0.0017
1.382
0.032
0.1497
0.0014
0.0451
0.0005
1.363
840
50
899
8
881
14

U-Pb dating of detrital zircons from the Wudangshan Group in the

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