Skip to main content
NCBI home page
ACS Omega logoLink to ACS Omega
. 2024 Mar 17;9(12):13483–13493. doi: 10.1021/acsomega.3c08214

Geochemical Characteristics of Trace Elements and Mineralization Model of the Ediacaran-Early Cambrian Phosphorites, South China

Lan Zhang †, Mingjie Zhang †, Guangyou Zhu ‡,*
PMCID: PMC10976387  PMID: 38559950

Abstract

graphic file with name ao3c08214_0004.jpg

As a nonrenewable resource, phosphate rock is an important support for the development and survival of the national economy. The regional distribution and output of phosphate rock in China are extremely uneven, and the amount of high-quality ore resources is relatively poor, which seriously restricts the development and utilization of phosphate rock resources in China. This paper briefly summarizes the distribution characteristics of phosphate rock resources and summarizes the characteristics and research progress of Ediacaran-early Cambrian phosphorus mineralization types, geological characteristics, and deposit genesis of the Yangtze platform in South China. The Ediacaran-early Cambrian sedimentary phosphorite deposits in China are mainly distributed in Yunnan, Guizhou, Hubei, Sichuan and Hunan provinces of the Yangtze platform, in which the early Cambrian phosphate deposits are also rich in rare earth elements, associated with uranium, nickel, molybdenum, vanadium, and other beneficial metal elements. The increase of atmospheric oxygen content at the Ediacaran-Cambrian boundary may have promoted the extensive oxygenation of the late Neoproterozoic oceans, so the Ediacaran-early Cambrian oceans generally showed a reductive environment, and there may be dynamic chemical stratification of the oxidation zone-sulfide zone-iron zone. Up to the early Cambrian, the redox stratified structure of Precambrian seawater may still be inherited, showing that the surface water is an oxidizing environment, changing to a reduction environment, and even wedge-shaped sulfide water is developed at the bottom of the deep basin. The main phosphorus sources are deep phosphorus-rich seawater, continental weathering, and deep hydrothermal activity of Ediacaran-early Cambrian marine sedimentary phosphorite deposits in South China. The genetic mechanisms of phosphorite deposits in the Yangtze platform in South China are mainly biogenic, upwelling phosphorus-forming theory, mechanical mineralization, and syn-sedimentary hot water mixed genesis. In the future, it is still necessary to further explore the internal relationship between phosphorus deposits and major geological events, the in situ analysis of microstructure of phosphate rock ores, and the genetic mechanism of phosphate deposits and the reconstruction of paleo-marine environment.

1. Introduction

The transitional period of the Ediacaran-early Cambrian witnessed dramatic changes in the marine environment, significant negative carbon isotope excursion of seawater and radiation evolution of metazoan in the early Cambrian,1−8 leaving abundant geological evidence in several sedimentary sequences. At the Precambrian-Cambrian boundary, it is accompanied by frequent dynamic changes in marine redox conditions,9−11 the rapid fluctuation of δ13Ccarb, long-term positive δ34Ssulfate excursion and instantaneous anomaly of δ95/97 Mo all record the frequent changes of marine environment,12,13 in response to the change of atmospheric-ocean oxygenation after the Snowball Earth event.14 Many studies on the characteristics of mercury isotopes, molybdenum isotopes and rare earth elements show that there is obvious chemical stratification in the marine water from Ediacaran to early Cambrian, and the increase of atmospheric oxygen content drives the regional oxidation of the shallow sea.13,15−17 During this period, a large-scale marine phosphorite deposited around the world, including two important metallogenic periods, namely, the Ediacaran (635–541Ma) and the early Cambrian (541–529Ma), which is widely distributed in Asia, Australia, Africa, and other regions.18 During this period, phosphate mineralization is closely related to the global carbon cycle, two Neoproterozoic oxidation events, and biological evolution, so the geochemical characteristics and paleo-marine environment of marine phosphorites in this period are ideal objects for in-depth analysis of the original geochemical information on seawater and the influence of paleo-marine environment on phosphorus mineralization.

The Ediacaran-early Cambrian phosphorus mineralization in China mainly developed in the Yangtze platform and the northern margin of the northwestern Tarim block, especially the Yangtze platform in south China, which is widely distributed in Yunnan, Guizhou, Hubei etc. In the past, many scholars have carried out detailed studies on the geological characteristics, process mineralogy, radioisotope chronology, enrichment mechanism, and mineralization of phosphorite deposits on the Yangtze platform.19−24 This paper summarizes the geological and geochemical characteristics of the Ediacaran-early Cambrian phosphorus-rich sedimentary series in South China, as well as the evolution characteristics of the paleo-marine environment in South China during the Ediacaran-early Cambrian transition period.

2. Distribution of Phosphate Rock Resources in the World and China

The world is rich in phosphate rock resources, but the geographical distribution is extremely uneven, mainly concentrated in Morocco/Western Sahara, China, Algeria, Syria, Jordan, Egypt, the United States, and Australia (Figure 1; Table 1). The total amount of phosphate resources in the world is about 300,000Mt, of which sedimentary phosphate rock deposits account for more than 95% of the total resources, which is the main industrial phosphate ore type.25 According to the geological conditions and genetic mechanism of the formation of phosphorus deposits, phosphorus deposits are divided into two types: primary phosphorus deposits and secondary phosphorus deposits. The primary phosphorus deposits can be divided into three types: endogenous magmatic phosphate deposits, exogenous sedimentary phosphate deposits, and metamorphic phosphorus deposits, while the secondary phosphorus deposits are mainly bird manure accumulation, weathering-leaching residue, and cave accumulation type. The global sedimentary phosphorite deposits are mainly distributed in the United States, China, the Middle East, and North Africa.25 The main metallogenic periods include late Proterozoic-Cambrian, the phosphate deposits are mainly distributed in Central and South Asia; Permian phosphorus is deposited in North America; Jurassic-early Cretaceous phosphorus is deposited in Eastern Europe; late Cretaceous-Eocene phosphorus deposit is mainly found in North Africa, the Middle East and Central Asia; Cenozoic Miocene phosphorus formation period is in the southeastern United States.26

Figure 1.

Figure 1

Open in a new tab

Global distribution map of phosphate resources (modified from Pufahl and Groat25).

Table 1. Global Distribution of Phosphate Resources25.

Country Resources/Mt Country Resources/Mt
Sedimentary deposits      
Morocco/W. Sahara 50,000 Tunisia 100
China 3,700 India 65
Senegal 2,200 Senegal 50
Syria 1,800 Togo 30
Jordan 1,300 Mexico 30
Egypt 1,250 Vietnam 30
United States 1,100 Total 65,661
Australia 1,030    
Saudi Arabia 956 Igneous deposits  
Peru 820 Brazil 315
Iraq 430 Russia 1,300
Other Countries 380 South Africa 1,500
Kazakhstan 260 Total 3,115
Israel 130    
    All sources of the world 68,776
Open in a new tab

China is not only the main supplier of global phosphate production, but also a large agricultural country, with an average annual demand of 11–12 million tons of phosphate fertilizer. China is rich in phosphate rock resources and various deposit types, but its geographical distribution is uneven. Endogenous magmatic and metamorphic phosphorus deposits are mainly distributed in North China and Tarim blocks, while sedimentary phosphorite deposits are mainly distributed in Yunnan, Sichuan, Guizhou, Hubei, and Hunan provinces around the Yangtze block (Table 2).27 The phosphogenic stage mainly includes the late Neoproterozoic Ediacaran, early Cambrian Meishucun stage, and early Devonian in China. Among them, the Ediacaran phosphorites are mainly distributed in central Guizhou, western Hunan and western Hubei. The early Cambrian phosphorites are distributed in three metallogenic belts of Sichuan-Yunnan, Sichuan-Shaanxi and central Guizhou, which is rich in rare earth elements and associated with metal elements such as uranium, nickel, molybdenum, and vanadium.28

Table 2. Distribution of Phosphate Deposits in China.

Classification Types Distribution P2O5/% Associated minerals References
Igneous deposits          
ultramafic-alkalic rock Fanshan Northern margin of North China Block 3%∼15% V, Ti, REE (27)
ultramafic rock-carbonatite Qieganbulake Northern margin of North China Block, Tarim Block 2%∼10% Nb, Th, REE (27)
alkalic rock   Liaoning, Shanxi 2%∼10% REE (27)
carbonatite Baiyan Obo Inner Mongolia, Xinjiang 4%∼10% Nb, Th, REE (27)
ultramafic rock Kawuliuke Tag Northern margin of North China Block, Tarim Block 2%∼10% V, Ti, Co (27)
mafic rock Maying Northern margin of North China Block, Tarim Block 2%∼10% V, Ti (27)
pegmatite Yousuopu Hebei, Inner Mongolia 11%∼29% REE (27)
greenstone belt Zhaobinggou ancient continent nucleus of North China, Shandong 3%∼5% Ti (27)
  Wulanwusu ancient continent nucleus of Liao-Ji 3%∼7% Ti (27)
Metamorphic deposits          
migmatite Mahsan Kiamusu Block 2%∼5% C (27)
sedimentary migmatite Haizhou Eastern margin of North China Block 12%∼16% Mn, Ca (27)
  Bulongtu Northern margin of North China Block 5%∼7% Fe, REE (27)
  Luotun Northern margin of North China Block 5%∼10% Fe (27)
Sedimentary deposits          
Sinian Kaiyang Southwestern margin of Yangtze Block 10%∼30% I (29)
  Jingxiang Southern margin of Yangtze Block 19%∼25% Ti, Cu, Pb (27)
  Shimen Southern margin of Yangtze Block 8%∼22% C (27)
  Xiangxi   17%∼19% Ca, Mg (27)
Cambrian Kunyang Western margin of Yangtze Block 26%∼30% Ca, Mg (30)
  Mabian Western margin of Yangtze Block 23%∼31% C, F (24)
  Tiantaishan Western margin of Yangtze Block 12%∼26% U, Mn (27)
  Xinhua Southern margin of Yangtze Block 10%∼26% REE (21)
  Xinji Eastern, northwestern margin of Yangtze Block 6%∼20% Ca (27)
  Pingtaishan Northern margin of Tarim Block 3%∼25% V (27)
  Hanyuan Eastern, northwestern margin of Yangtze Block 11%∼23% K (27)
  Dongxi Zhejiang, Jiangxi 5%∼23% Ni, Pt, V (27)
  Damao passive margin of Sanya 12%∼19% Mn (27)
Devonian Shifang foreland thrust belt of Longmenshan 20%∼28% REE (27)
Weathered deposits          
weathering - leaching accumulation Huangjingping   18%∼28% Th, U, REE (27)
cave accumulation Tiandeng   -   (27)
  Ceheng   11%∼33%   (31)
guano accumulation Xisha islands Hainan, south islands -    
Open in a new tab

3. Paleo-Marine Environment of the Ediacaran-Early Cambrian in South China

The Ediacaran-early Cambrian transition period was an important period of early earth evolution, which recorded the radiation differentiation conditions and evolution of metazoans as well as the drastic changes of marine chemical conditions accompanied by the gradual oxidation of the global atmosphere at that time. Marine phosphorite mineralization is not only closely related to the biogeochemical cycle of phosphorus but also related to paleogeography, paleomarine environment, and biological evolution. The late Neoproterozoic Ediacaran-early Cambrian phosphorite deposits in China are mainly distributed in Guizhou, Hubei and Yunnan, and their geological characteristics are as follows:1) the distribution is controlled by paleogeographic environment; 2) the deposits are distributed along the direction of paleo-plate movement; 3) there are rich fossil records; 4) the deposit is of high grade and associated with REE (rare earth elements) mineralization.

The early Cambrian black rocks of the Yangtze platform in South China are widely distributed, forming a series of Barite, phosphorite and Ni–Mo polymetallic sulfide deposits and rich in biological fossils, which are favorable objects for studying the changes of the marine environment in the geological history.32,33 Previous studies have shown that early Cambrian organic-rich shales were deposited under anoxia caused by global transgression events and were affected by many factors: primary productivity, sedimentary rate, upwelling range and local hydrothermal activity,34−36 and the gradual expansion process and influence of surface oxygen-containing seawater in the ocean under the background of the increase of oxygen content in the atmosphere during the early Cambrian. In the process of phosphorus enrichment, collophane precipitates directly from seawater or pore water, recording paleo-oceanic environmental information.37 Therefore, the trace elements, rare earth elements, and isotopic composition characteristics of phosphate rocks can reflect the characteristics of paleo-marine environment, which provide favorable conditions for evaluating the changes of paleo-oceanic redox state, biological mineralization, and marine geochemical vertical changes.

In the early Ediacaran, the southeastern margin of the Yangtze platform can be divided into four sedimentary facies from NW-SE: nearshore tidal flat facies, shallow slope facies with barrier shoals, deep slope facies and deep basin facies.38 The Ediacaran Doushantuo Formation is composed of clastic rocks, phosphorite rocks and carbonate rocks, integrated or pseudointegrated on the Nantuo Formation tillites, integrated with Dengying Formation carbonate rocks, and the sedimentary time is limited to 635–551Ma.39,40 The Doushantuo Formation recorded the oxidation of the water column during the late Neoproterozoic Oxidation Event (NOE) and the accompanying phosphate mineralization event.36,41 The phosphorus-rich deposit of the Dengying Formation was overlying the black shale of the early Cambrian Niutitang Formation, and the sedimentary time is limited to 551–542Ma.42 The phosphorus deposits are mostly found in the semiconfined lagoon environment of the platform margin shoals.43

After the late Neoproterozoic ice age, the Yangtze Platform rapidly transformed from slope facies carbonate to shelf-slope facies deposits dominated by clastic rocks, phosphorite rocks and carbonate rocks,44 which can be divided into southwest palaeo-continent and eastern coastal tidal flat-shallow slope-deep basin facies and formed early Cambrian phosphorus-rich deposits under the influence of transgression and upwelling. The early Cambrian phosphorite deposits in China were mainly deposited in shelf environment, and the typical sedimentary areas are mainly Gezhongwu Formation and Meishucun Formation, in which Gezhongwu Formation phosphorites in Zhijin, Guizhou Province is offshore deposit, and the Meishucun Formation in eastern Yunnan Province is coastal deposit with relatively shallow water,37 both of which contain a large number of small shell fossils (SSF).

The Ediacaran Doushantuo Formation in South China are mainly distributed in central Guizhou, western Hubei and western Hunan, and phosphorite and carbonate are widely developed, mainly composed of dolomite phosphorite, clastic phosphorite, granular phosphorite, siliceous phosphorite and phosphate dolomite (Figure 2a–d), with an average P2O5 content of 28.96%.38,45 The REE content in Weng’an phosphorus rocks are (18.59–285.91) × 10–6, Ce/Ce* = 0.56–1.02. The REE distributed pattern is characterized by typical “cap type”, showing slight enrichment of MREE (middle rare earth elements), suggesting that organic matter is involved in phosphorus mineralization during Doushantuo period.46 The stromatolite phosphorite (Figure 2 e–l) of Late Ediacaran Dengying Formation is mainly found in the Weng’an area. The milky white and gray columnar stromatolite and dark gray fine crystalline dolomite are interspersed vertically, and colloidal and granular texture is developed, with average P2O5 content is 19.93%.38,47 The Cambrian Niutitang Formation is mainly phosphate nodules, clastic phosphorite and siliceous phosphorite (Figure 2 m–p), with clastic texture and grain texture, with average P2O5 content is 28.58%.40,43

Figure 2.

Figure 2

Open in a new tab

Late Ediacaran-early Cambrian phosphorus-rich sedimentary types in South China. a-phosphorite, Doushantuo Fm, 5 × 10(+); b-detrital phosphorus dolomite, Doushantuo Fm, 5 × 10(−); c-detrital phosphorite, Doushantuo Fm, 5 × 10(+); d-dolomitic phosphorite, Doushantuo Fm, 5 × 10(+); e–g stromatolite phosphorite, Dengying Fm, 5 × 10(+); h-layered phosphorus dolomite, Dengying Fm, 5 × 10(−); i–l-algal pellet of stromatolite phosphorite, Dengying Fm (scanning electron microscope); m-phosphorus dolomitic limestone, Niutitang Fm, 10 × 10(+); n-silicic phosphortie, Niutitang Fm, 10 × 10(+); o-phosphorus nodules, Niutitang Fm, 10 × 10(−); p-dolomitic phosphorite, Niutitang Fm, 10 × 10(−).

The increase of atmospheric oxygen during the late Ediacaran-early Cambrian may have promoted extensive ocean oxygenation at the end of Neoproterozoic, and the atmospheric oxygen content may reach 10%–40%PAL (Present Atmospheric Level),48 which also caused the evolution of the Ediacaran biota and the subsequent Cambrian metazoans explosion.49 The exponential increase of oxidation–reduction sensitive elements in marine sediments also indicates that the once widespread anoxic environment is transforming into an oxidizing environment, but intermittent anoxic and ferritic environment may still occur in the deep basin of the Early Cambrian Yangtze Platform.1,50 Li et al.4 proposed that the dynamic chemical stratification of oxidation zone-sulfide zone-iron zone was maintained in the Ediacaran to Early Cambrian ocean and believed that the chemical stratification from nearshore to deep sea included oxidation zone, nitrate reduction zone, iron and manganese reduction zone, sulfate reduction zone, methanogenic zone and iron mineralization zone.51

During the Early Cambrian, the Yangtze Platform suffered from transgression from southeastern to northeastern, its sedimentary facies gradually transited from shallow carbonate to continental shelf slope and deep basin facies.43 Among the important mineralization sequences widely distributed in South China, phosphorite is usually deposited on the continental shelf from the coast to the shelf edge. Weng’an and Kaiyang in central Guizhou were shallow platform facies deposits, while Xiangyang in western Hubei belonged to deep basin facies deposits. Therefore, shallow basin and bay tidal flat environment at the margin of paleo-continent or underwater uplift are ideal places for phosphorus mineralization, while shelf and basin in deep area are mostly thin layer, nodule or lenticular phosphorites, which do not have geological conditions for forming large-scale high-grade phosphorite deposits.36

In recent years, with the development of metal stable isotope analysis technology, based on C, S isotopes, stable isotopes such as U, Mo and Fe have been gradually applied to paleo-marine environment research, becoming effective indicators for tracing the redox state of marine water.7,13,52,53 Many studies based on various geochemical indicators such as inorganic carbon isotope, molybdenum isotope and sulfur isotope show that there is a highly stratified redox structure in the Ediacaran to Early Cambrian oceans in the Yangtze region of South China.54−57 At the Doushantuo Formation, Dengying Formation and Niutitang Formation in Ediacaran to Early Cambrian in South China, synthesizing many discrimination indexes of trace elements and rare earth elements, the average V/(V + Ni) value is 0.70, 0.79, and 0.86 respectively, and the average δU value is 1.83, 1.92, and 1.87, respectively (Table 3); δCe always shows negative anomaly (δCe value is 2.70, 1.74, and 1.57 respectively, Table 4), and the negative anomaly trend gradually weakens with time. It is considered that the Ediacaran to Early Cambrian phosphorus mineralization period in South China is generally a reducing environment, but with the end of the ice age, climate warming promotes the enhancement of continental chemical weathering and promotes the increase of oxygen content, and there are local oxidation events. Due to the influence of transgression, the sea level fluctuates frequently, which makes the Ce negative anomaly weaken.

Table 3. Trace Element Characteristics of Ediacaran to Early Cambrian Phosphorite in South Chinaa.

Area Strata Number Lithology Co/μg/g Ni/μg/g Th/μg/g U/μg/g V/μg/g Cr/μg/g V/(V+Ni) δU
Tuanshanpub Dengying Formation Z-3 uranium-bearing phosphorite 9.46 375.40 0.96 320.60 1201.50 30.20 0.76 2.00
    Z-4 uanium-bearing phosphorite 8.90 285.60 1.45 330.10 1586.00 256.30 0.85 2.00
    Z-5 uanium-bearing phosphorite 33.28 346.20 1.24 658.40 948.50 18.50 0.73 2.00
Xinchongc   XC-2 phosphorite 3.55 103.00 6.85 3.47 1501.00 916.00 0.94 1.21
    XC-2-1 phosphorite 4.61 72.20 0.19 13.60 1368.00 503.00 0.95 1.99
    XC-8 phosphorite 10.30 79.80 0.18 11.70 1232.00 532.00 0.94 1.99
Xia’and Dengying Formation WLX-2 sandy phosphorite 0.30 2.20 0.40 30.30 12.00 30.00 0.85 1.99
    WLX-3 phosphorus dolomite 0.30 2.10 0.40 7.40 15.00 13.00 0.88 1.96
    WLX-4 stromatolite phosphorite 0.20 0.50 <0.2 24.30 7.00 10.00 0.93  
    WLX-5 phosphorus dolomite 1.00 4.00 0.60 5.70 8.00 36.00 0.67 1.93
    WLX-6 stromatolite phosphorite 0.20 0.20 <0.2 13.20 6.00 8.00 0.97  
    WLX-7 phosphorus dolomite 0.70 1.60 0.80 6.10 11.00 19.00 0.87 1.92
    WLX-8 phosphorus dolomite 0.80 8.60 0.60 4.10 5.00 25.00 0.37 1.91
Weng’ane Doushantuo Formation YP-1-A granular phosphorite 58.60 9.25 2.31 12.50 17.10 10.70 0.65 1.88
    YP-4-A granular phosphorite 27.50 8.24 2.35 13.30 14.50 9.73 0.64 1.89
    YP-5-A granular phosphorite 25.80 7.89 2.37 14.40 13.30 5.96 0.63 1.90
    YP-7-A biotic phosphorite 15.80 12.80 0.53 4.10 13.50 14.00 0.51 1.92
    BD-1-A biotic phosphorite 18.10 10.00 0.66 11.50 40.40 18.80 0.80 1.96
    BD-2-A biotic phosphorite 14.00 6.99 0.13 4.15 21.10 5.04 0.75 1.98
    BD-8-B granular phosphorite 19.60 8.97 7.85 8.42 74.40 44.60 0.89 1.53
    BD-9-A detrital phosphorite 18.70 19.10 5.44 9.69 57.80 30.90 0.75 1.68
    BD-10-A detrital phosphorite 21.60 18.80 4.31 8.13 41.10 24.70 0.69 1.70
Open in a new tab
a

Notes:δU = 6U/(3U + Th).

b,c

From refs (58, 59).

d

From ref (47).

e

From ref (45).

Table 4. Rare Earth Element Characteristics of Ediacaran to Early Cambrian Phosphorite in South China (with Average Values)a.

Strata Niutitang Formation Dengying Formation Doushantuo Formation
number of samples/piece 153 45 164
∑REY/μg/g 653.74 63.26 86.51
LREE/HREE 5.84 6.06 6.26
δCe 1.57 1.74 2.70
δEu 0.23 0.24 0.26
Ceanom 0.07 0.13 0.29
(La)N/(Yb)N 19.11 16.71 11.93
(La)N/(Sm)N 7.28 6.95 5.56
Open in a new tab
a

Note: “N” stands for continental upper crust standardization, standardized data from [60]; δCe = 2CeN/(LaN + PrN); δEu = 2EuN/(SmN + GdN); Ceanom = lg[3CeN/(2LaN + NdN)].

δ56Fe in the lower and upper phosphate layers of Doushantuo Formation in Weng ’an is −0.33‰∼0.27‰, −0.32‰∼0.21‰ respectively,38 and the oxidation–reduction sensitive element content in the upper phosphate layer (Mo = 0.23–1.35 μg/g, U = 3.79–7.05 μg/g, V = 13.9–24.5 μg/g) is obviously lower than that in the lower layer (Mo = 1.52–14.00 μg/g, U = 5.53–22.10 μg/g, V = 9.7–52.7 μg/g),61 the Ceanom = −0.26∼−0.29 in upper phosphate layer, and Ceanom = −0.065∼−0.077 in lower layer. In addition, Fe-redox pumping is also key for phosphorus enrichment. In shallow oxidation-sub oxidation ocean, iron hydroxide (FeOOH) can adsorb a large amount of phosphorus, forming iron–phosphorus complex (PO43–·FeOOH) and sinking into bottom sediments. In the anoxic bottom water, these iron–phosphorus complexes deoxidize phosphorus and release it into the water column, and with the strong upwelling action, the deep phosphorus-rich seawater enters the shallow ocean.23

All the geochemical evidence mentioned above indicate that the late Neoproterozoic ocean changed from anoxic to oxidizing environment,45 and the oxidation–reduction interface gradually shifted from shallow ocean to deep ocean with the expansion of seawater oxidation range. Wen et al.62 analyzed δ97/95 Mo of phosphorite in Meishucun Formation, Yunnan Province, and proposed that the early Cambrian ocean inherited the oxidation–reduction layered structure of Precambrian ocean, and the surface water was in oxidation environment, which changed to reduction environment in depth, and even wedge-shaped sulfide water column may be locally developed at the bottom. Zhu et al.63 studied Hg abundance and δ15N in slope facies of Niutitang Formation in Songtao, Guizhou Province. It is considered that the enhancement of nitrogen fixation and nitrification of marine organisms in the early Cambrian reduced environment caused obvious negative excursion of δ15N and abnormal enrichment of Hg, and the gradual oxidation of seawater and the decrease of organic matter buried in the later stage led to the decrease of Hg concentration, which showed the dynamic chemical stratification characteristics of the ocean from Ediacaran to Early Cambrian and the frequent changes of marine environment during this period.

4. Genetic Mechanism of Phosphorites

4.1. Phosphorus Sources

The material source of phosphorus is the premise of the study on the genetic mechanism of phosphate deposits. It is considered that the main sources of phosphorus in marine sedimentary phosphate rocks are the following. 1) Seawater, that is, phosphorus-rich bottom water brought by upwelling. After the death of the organism, the body’s decomposition may release phosphate, which is absorbed and sunk by pore water. Under the influence of transgression, frequent sea level fluctuations provide a power drive for the exchange of deep bottom water and shallow oxidized seawater, and the upwelling carries the deep phosphorus-rich bottom water, which brings a lot of phosphorus to the shallow field. 2) Terrigenous detrital, under the background of the great oxidation event and the breakup of Rodinia supercontinent, the erosion and chemical weathering of paleo-continent were strengthened, and a large amount of phosphorus-bearing terrigenous debris was imported into the ocean. 3) Deep hydrothermal activity, submarine volcanic eruption brought a large amount of Sr, U, P, Si etc., the global 87Sr/86Sr of Ediacaran-Cambrian marine sediments (>0.7090)64 also indicates that the seafloor hydrothermal activity was frequent during this period, and hydrothermal elements were imported, resulting in Sr isotope fractionation.25,64

4.2. Biological Genesis

The discovery of stromatolite phosphorite, microfossil assemblages, and algae fossils in the late Neoproterozoic indicates that microorganisms played an important role in the process of phosphate mineralization. The Doushantuo Formation phosphorite in Weng’an and Kaiyang area of Guizhou are rich in biologically related elements such as Cr, Co, Sr and Pb, also found that the phosphate sediments are mainly composed of calcium phosphate minerals and have fossils,65 they all indicate that the biological prosperity may have a positive effect on phosphorite deposition of the Doushantuo period. The stromatolite phosphorite and gel phosphate rock of the Ediacaran Dengying formation are characterized by low REE concentrations, with an average REE content of 63.26 μg/g,47,53 combined with the REE characteristics of modern marine organisms (such as modern fishbone fossils ∑ REE < 100 μg/g),66 indicating that bacteria and algae were involved in phosphate mineralization during the Precambrian period.67 Stromatolites, microfossils, algae fossils in the phosphorus-rich strata of the Ediacaran Doushantuo Formation and Dengying Formation, and many small shell fossils in the early Cambrian Meishucun Formation (Gezhongwu Formation) indicate that in the two phosphorus mineralization events there is a close relationship between the occurrence of high-quality and high-grade phosphate deposits and biological activities.

Biological participation in phosphorus mineralization is mainly reflected in two aspects: biological organisms absorb phosphorus from seawater and pore water, and after the death of organisms, the degradation of organic matter by bacteria causes phosphorus to decompose. Phosphate is concentrated into pore water. In addition, the life activities of organisms also indirectly change the physical and chemical conditions of the ocean. Ph value of pore water increases due to the decomposition of organic matter, which promotes the crystallization of some phosphate to form authigenic apatite minerals such as fluoroapatite and fine-grained apatite.68,69 The other phosphorus of the wreckage is directly consolidated under diagenesis to form phosphate nodules, which are accumulated and mineralized.70

4.3. Upwelling Genesis

Upwelling is the most possible mechanism to explain the genesis of marine phosphorite deposits, but it is closely related to biological processes. It is considered that during the decomposition of biological remains, some phosphorus is released and enriched in the bottom water, and the upwelling is an important driving force for the migration of deep phosphorus-rich bottom water to shallow coastal areas. For the phosphorus-rich seawater brought to the shallow ocean by the upwelling, due to the decrease of pressure and the increase of temperature, the solubility of phosphate in the water column decreases and directly precipitates to form phosphorus-rich sediments. On the other hand, the nutrient elements reaching the shallow ocean increase the primary productivity and prosper the organisms, which in turn absorb the phosphate in the pore water and enrich the phosphorus. However, with the deepening of the study, it is found that the modern phosphorus mineralization in Peru and Namibia is mainly distributed in the continental shelf and slope environment under the upwelling area.71 Therefore, it is considered that the upwelling is beneficial to the upward migration of bottom phosphorus-rich seawater, but it is not a necessary condition for the phosphorus mineralization, and the migration-enrichment process of phosphorus-rich bottom water in the shallow ocean is still controversial.

4.4. Mechanical Mineralization

Most of phosphorite deposits are mechanical sedimentation of the Ediacaran-early Cambrian in South China, which is the initial enrichment of phosphorus-rich sediments in the early stages is the product of erosion and redeposition under the influence of geological forces. During the study of phosphorus-rich sedimentary genesis of Kaiyang and Weng’an Doushantuo Formation in central Guizhou, Wang et al.72 considered that Weng’an phosphorus rock experienced at least two stages of transgression-retrogression cycle, and accordingly, the phosphate mineralization of Doushantuo Formation was divided into three stages: 1) In the early stage, transgression was frequent, carbonate tidal flat deposits were developed in central Guizhou. And the water depth deepened from south to north, the upwelling and biological prosperity cause the deposition of phosphorus-rich organic matter, which degrades the organic matter at the redox interface, releases a large amount of phosphate, and completes the initial enrichment. 2) In the middle stage, with the large-scale retrogression, the carbonate cements were dissolved by the erosion and leaching of the primary phosphorite, and the broken clastic particles were deposited in situ or accumulated after transportation, so as to improve the phosphorus grade. 3) In the late stage, the transgression once again caused the sea level to rise and the microbial activity flourished, and the early clastic phosphorite continued to accept phosphorus deposition and cementation, resulting in the second phosphorus mineralization event. In summary, it is considered that the transgression in the late Neoproterozoic triggered the exchange between the deep phosphorus-rich seawater and the shallow seawater, and the widely distributed shallow ocean was an ideal place for phosphorus accumulation. The rhythmic variation characteristics of the lithology of the Doushantuo Formation and the transgression-retrogression cycles of the two stages also indicate that the intermittent fluctuation of sea level has led to the formation of phosphorite-carbonate deposits with cycle characteristics in central Guizhou.

4.5. Syn-Sedimentary Hydrothermal Genesis

The strong hydrothermal activity can change the chemical composition of seawater and marine environment and provide a habitat for biological communities.15 The major and microgeochemical indexes of phosphorite in Doushantuo Formation in central Guizhou indicate that hydrothermal activity is accompanied by transgression-retrogression cycle, which is an important contributor to phosphorus source of late Neoproterozoic phosphorus mineralization events, it also plays an important role in phosphorus transport and deposition.45 Liu et al.73 found that mineral fluid inclusions (quartz and muscovite) in phosphorite of the Lower Cambrian Gezhongwu Formation in Zhijin, Guizhou, which is direct evidence that hydrothermal activity is involved in phosphorus mineralization. At the same time, the phosphate nodules preserved in the black shale also recorded some information on volcanic and hydrothermal activities of the Lower Cambrian Niutitang Formation in South China. It was found that the volcanic ash and hydrothermal activities carried a large amount of nutrients, which promoted the development of marine primary productivity and produced many phosphate-rich water masses.41 Silicon isotope measurements of authigenic quartz in the upper phosphate layer of Zhongyicun member in Yunnan (δ30Si = −0.40‰),64 the δ13C of phosphorite in Zhongyicun member in Laolin area (δ13C = −3.20‰∼0‰)74 also indicate that hydrothermal fluid was added in the process of phosphate mineralization.

Although the earth has experienced extensive weathering and imported many terrigenous materials, the strontium isotopic composition of sediments is still lower than that of terrestrial materials due to strong hydrothermal activities.12 The geochemical characteristics of the above phosphorite deposits indicate that the seafloor hydrothermal solution can provide some phosphorus and metal-ore-forming elements in the mineralization process. Some scholars associate hydrothermal activities with biological activities and believe that submarine hot water provides energy and rich nutrients for the biota,75 which indirectly promotes the improvement of marine primary productivity and is beneficial to the accumulation and precipitation of phosphorus.

Marine sedimentary phosphorite deposits have been studied for a long time. Scholars have put forward a variety of genetic mechanisms and models about the phosphorite deposits, but they have also been controversial. For a long time, a large number of detailed studies have been carried out on the temporal and spatial distribution, rock and mineral assemblage, lithofacies, paleogeography, major and trace elements and isotope geochemistry of phosphorite, it is considered that the direct precipitation of phosphorus-rich seawater, carbonate metasomatism, microbial interaction, or the interaction of the above processes may produce different phosphorus-bearing sedimentary facies (Figure 3).11 Therefore, the genetic mechanism of phosphate deposits cannot be demonstrated solely from one aspect; we should pay more attention to the internal relationship between phosphorus mineralization and major geological events. And the microfabric analysis of phosphate rocks should be strengthened, comprehensively considering various influencing factors to discuss the process of phosphorus deposition and mineralization.

Figure 3.

Figure 3

Open in a new tab

Sedimentary model of the phosphorite deposit.

5. Conclusions

  • 1)

    China is very rich in phosphate resources, but there are extreme imbalances of geographical distribution and utilization etc. There are many types of phosphate deposits, and sedimentary phosphate rock deposits are the main industrial phosphate ores. The Ediacaran-early Cambrian sedimentary phosphorite deposits are mainly distributed in Yunnan, Guizhou, Hubei, Sichuan, and Hunan provinces of the Yangtze platform in South China, in which the early Cambrian phosphorite deposits are also rich in rare earth elements, associated with uranium, nickel, molybdenum, vanadium and other beneficial metal elements.

  • 2)

    The paleo-marine environment from Ediacaran to early Cambrian changed frequently, showing a reductive environment overall, and there may be dynamic chemical stratification of oxidation zone-sulfide zone-iron zone. However, due to the influence of transgression, the sea level fluctuates frequently, and in the early Cambrian, it may still inherit the redox stratified structure of Precambrian ocean, showing that the surface water is an oxidizing environment, changing to a deep reduction environment, and even wedge-shaped sulfide areas are developed at the deep basin.

  • 3)

    The main phosphorus sources of Ediacaran-early Cambrian marine sedimentary phosphorite deposits in South China are deep phosphorus-rich seawater, terrigenous detritus, and hydrothermal activity. The genetic mechanism and metallogenic model of marine sedimentary phosphorite deposits have been controversial. At present, the established genetic mechanisms mainly include biogenic mechanism, upwelling mechanism, mechanical mineralization, and syn-sedimentary hydrothermal genesis. Various genetic hypotheses are not independent, but interrelated and influence each other, so in the future, it is necessary to further explore the internal relationship between phosphorus deposits and major geological events and deepen the genetic mechanism and the reconstruction of paleo-marine environment.

Acknowledgments

This project was funded by the National Natural Science Foundation of China (Grant No. 42073068).

The authors declare no competing financial interest.

References

  1. Canfield D. E.; Poulton S. W.; Narbonne G. M. Late-Neoproterozoic deep-ocean oxygenation and the rise of animal life. Science 2007, 315 (5808), 92–95. 10.1126/science.1135013. [DOI] [PubMed] [Google Scholar]
  2. Canfield D. E.; Poulton S. W.; Knoll A. H.; Narbonne G. M.; Ross G.; Goldberg T.; Strauss H. Ferruginous conditions dominated later Neoproterozoic deep-water chemistry. Science 2008, 321 (5891), 949–952. 10.1126/science.1154499. [DOI] [PubMed] [Google Scholar]
  3. Mort H. P.; Adatte T.; Föllmi K. B.; Keller G.; Steinmann P.; Matera V.; Berner Z.; Stüben D. Phosphorus and the roles of productivity and nutrient recycling during oceanic anoxic event 2. Geology 2007, 35 (6), 483–486. 10.1130/G23475A.1. [DOI] [Google Scholar]
  4. Li C.; Love G. D.; Lyons T. W.; Fike D. A.; Sessions A. L.; Chu X. A stratified redox model for the Ediacaran ocean. Science 2010, 328 (5974), 80–83. 10.1126/science.1182369. [DOI] [PubMed] [Google Scholar]
  5. Crosby C. H.; Bailey J. V.; Sharma M. Fossil evidence of iron-oxidizing chemolithotrophy linked to phosphogenesis in the wake of the Great Oxidation Event. Geology 2014, 42 (11), 1015–1018. 10.1130/G35922.1. [DOI] [Google Scholar]
  6. Chen X.; Ling H. F.; Vance D.; Shields-Zhou G. A.; Zhu M.; Poulton S. W.; Och L. M.; Jiang S. Y.; Li D.; Cremonese L.; Archer C. Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals. Nat. Commun. 2015, 6, 7142. 10.1038/ncomms8142. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Wei W.; Frei R.; Gilleaudeau G. J.; Li D.; Wei G. Y.; Chen X.; Ling H. F. Oxygenation variations in the atmosphere and shallow seawaters of the Yangtze Platform during the Ediacaran Period: Clues from Cr-isotope and Ce-anomaly in carbonates. Precambrian Research 2018, 313, 78–90. 10.1016/j.precamres.2018.05.009. [DOI] [Google Scholar]
  8. Qin Z.; Xu D. T.; Kendall B.; Zhang X. L.; Ou Q.; Wang X. Q.; Li J.; Liu J. G. Molybdenum isotope-based redox deviation driven by continental margin euxinia during the early Cambrian. Geochim. Cosmochim. Acta 2022, 325, 152–169. 10.1016/j.gca.2022.03.007. [DOI] [Google Scholar]
  9. Ling H. F.; Chen X.; Li D.; Wang D.; Shields-Zhou G. A.; Zhu M. Cerium anomaly variations in Ediacaran-earliest Cambrian carbonates from the Yangtze Gorges area, South China: Implications for oxygenation of coeval shallow seawater. Precambrian Research 2013, 225, 110–127. 10.1016/j.precamres.2011.10.011. [DOI] [Google Scholar]
  10. Schroder S.; Grotzinger J. P. Evidence for anoxia at the Ediacaran-Cambrian boundary: the record of redox-sensitive trace elements and rare earth elements in Oman. Journal of Geological Society 2007, 164, 175–187. 10.1144/0016-76492005-022. [DOI] [Google Scholar]
  11. Stammeier J. A.; Hippler D.; Nebel O.; Leis A.; Grengg C.; Mittermayr F.; Kasemann S. A.; Dietzel M. Radiogenic Sr and stable C and O isotopes across Precambrian-Cambrian transition in marine carbonatic phosphorites of Malyi Karatau (Kazakhstan)-Implications for paleo-environmental change. Geochemistry, Geophysics, Geosystems 2019, 20 (1), 3–23. 10.1029/2018GC007767. [DOI] [Google Scholar]
  12. Halverson G. P., Hurtgen M. T., Porter S. M., Collins A. S.. Chapter 10 Neoproterozoic-Cambrian Biogeochemical Evolution. In Developments in Precambrian Geology; Gaucher C., Sial A. N., Frimmel H. E., Halverson G. P., Eds.; Elsevier, 2009; Vol. 16, pp 351–365. [Google Scholar]
  13. Wen H.; Fan H.; Zhang Y.; Cloquet C.; Carignan J. Reconstruction of early Cambrian ocean chemistry from Mo isotopes. Geochim. Cosmochim. Acta 2015, 164, 1–16. 10.1016/j.gca.2015.05.008. [DOI] [Google Scholar]
  14. Anbar A. D.; Duan Y.; Lyons T. W.; Arnold G. L.; Kendall B.; Creaser R. A.; Kaufman A. J.; Gordon G. W.; Scott C.; Garvin J.; Buick R. A whiff of oxygen before the great oxidation event?. Science 2007, 317, 1903–1906. 10.1126/science.1140325. [DOI] [PubMed] [Google Scholar]
  15. Zhu G.; Wang P.; Li T.; Zhao K.; Zheng W.; Feng X.; Shen J.; Grasby S. E.; Sun G.; Tang S.; Yan H. Mercury record of intense hydrothermal activity during the early Cambrian, South China. Palaeogeography, Palaeoclimatology, Palaeoecology 2021, 568, 110294 10.1016/j.palaeo.2021.110294. [DOI] [Google Scholar]
  16. Cheng M.; Li C.; Zhou L.; Algeo T. J.; Zhang F.; Romaniello S.; Jin C. S.; Lei L. D.; Feng L. J.; Jiang S. Y. Marine Mo biogeochemistry in the context of dynamically euxinic mid-depth waters: A case study of the lower Cambrian Niutitang shales, South China. Geochim. Cosmochim. Acta 2016, 183, 79–93. 10.1016/j.gca.2016.03.035. [DOI] [Google Scholar]
  17. Cheng M.; Li C.; Zhou L.; Feng L. J.; Algeo T. J.; Zhang F. F.; Romaniello S.; Jin C. S.; Ling H. F.; Jiang S. Y. Transient deep-water oxygenation in the early Cambrian Nanhua Basin, South China. Geochim. Cosmochim. Acta 2017, 210, 42–58. 10.1016/j.gca.2017.04.032. [DOI] [Google Scholar]
  18. Yang H.; Xiao J.; Xia Y.; Zhao Z.; Xie Z.; He S.; Wu S. Diagenesis of Ediacaran-early Cambrian phosphorite: Comparisons with recent phosphate sediments based on LA-ICP-MS and EMPA. Ore Geology Reviews 2022, 144, 104813 10.1016/j.oregeorev.2022.104813. [DOI] [Google Scholar]
  19. Chen D. F.; Dong W. Q.; Zhu B. Q.; Chen X. P. Pb-Pb ages of Neoproterozoic Doushantuo phosphorites in South China: Constraints on early metazoan evolution and glaciation events. Precambrian Research 2004, 132 (1–2), 123–132. 10.1016/j.precamres.2004.02.005. [DOI] [Google Scholar]
  20. Chen Y.; Jiang S.; Ling H.; Feng H.; Yang J.; Chen J. Pb-Pb isotope dating of black shales from the Lower Cambrian Niutitang Formation, Guizhou Province, South China. Progress in Natural Science 2003, 13 (10), 771–776. 10.1080/10020070312331344410. [DOI] [Google Scholar]
  21. Zhang J.; Ni Y.; Liang J. Characteristics of mineralogical technology about medium-low grade bio-chip containing the rare earth dolomitic phosphorite in Xinhua, Zhijin, Guizhou. Journal of Rare Earths 2010, 28 (Supplement 1), 525–527. 10.1016/S1002-0721(10)60333-X. [DOI] [Google Scholar]
  22. Ishikawa T.; Ueno Y.; Shu D.; Li Y.; Han J.; Guo J.; Yoshida N.; Komiya T. Irreversible change of the oceanic carbon cycle in the earliest Cambrian: High-resolution organic and inorganic carbon chemo-stratigraphy in the Three Gorges area, South China. Precambrian Research 2013, 225, 190–208. 10.1016/j.precamres.2011.10.004. [DOI] [Google Scholar]
  23. Schwid M. F.; Xiao S.; Hiatt E. E.; Fang Y.; Nolan M. R. Iron phosphate in the Ediacaran Doushantuo Formation of South China: A previously undocumented marine phosphate sink. Palaeogeography, Palaeoclimatology, Palaeoecology 2020, 560, 109993 10.1016/j.palaeo.2020.109993. [DOI] [Google Scholar]
  24. Wang D.; Struck U.; Ling H. F.; Guo Q. J.; Shields-Zhou G. A.; Zhu M. Y.; Yao S. P. Marine redox variations and nitrogen cycle of the early Cambrian southern margin of the Yangtze Platform, South China: Evidence from nitrogen and organic carbon isotopes. Precambrian Research 2015, 267, 209–226. 10.1016/j.precamres.2015.06.009. [DOI] [Google Scholar]
  25. Pufahl P. K.; Groat L. A. Sedimentary and igneous phosphate deposits: Formation and exploration: An invited paper. Economic Geology 2017, 112 (3), 483–516. 10.2113/econgeo.112.3.483. [DOI] [Google Scholar]
  26. Orris G. J.; Dunlap P.; Wallis J. C.. Phosphate Occurrence and Potential in the Region of Afghanistan, Including Parts of China, Iran, Pakistan, Tajikistan, Turkmenistan, and Uzbekistan, with a section on geophysics written by Jeff Wynn. U.S. Geological Survey Open-File Report 2015-1121; United States Geological Survey, 2015. 10.3133/ofr20151121. [DOI]
  27. Xia X. H.; Hao E. H. Genetic classification of phosphate deposits in China. Geology of Chemical Minerals 2012, 34 (01), 1–14. [Google Scholar]
  28. Zhang Z.; Jiang Y.; Niu H.; Xing J.; Yan S.; Li A.; Weng Q.; Zhao X. Enrichment of rare earth elements in the early Cambrian Zhijin phosphorite deposit, SW China: Evidence from francolite micro-petrography and geochemistry. Ore Geology Reviews 2021, 138, 104342 10.1016/j.oregeorev.2021.104342. [DOI] [Google Scholar]
  29. Wang Z. P.; Zhang Y. G.; Du Y. S.; Chen G. Y.; Liu J. Z.; Xu Y. Y.; Tan D. W.; Li L.; Wang D. F.; Wu W. M. Reconstruction of quantitative lithofacies palaeogeography of the Sinian Doushantuo Age of phosphorite depositional zone in Kaiyang area, central Guizhou Province. Journal of Palaeogeography 2016, 18 (03), 399–410. [Google Scholar]; (Chinese with English abstract)
  30. Gao J. C.; Rong H. F.; Xu J. B.; Yang J. H. Geological characteristics and causes of Maliping phosphorite in Dongchuan, Kunming. Journal of Kunming University of Science and Technology (Natural Science) 2008, 12–17. [Google Scholar]; (Chinese with English abstract)
  31. Cheng G.; F He Y. Metallogenic conditions and model of weathered phosphate deposits in Zheheng, Guizhou. Acta Mineralogica Sinica 2016, 36 (02), 189–197. [Google Scholar]; (Chinese with English abstract)
  32. Jin C.; Li C.; Algeo T. J.; Planavsky N. J.; Cui H.; Yang X.; Zhao Y.; Zhang X.; Xie S. A highly redox-heterogeneous ocean in South China during the early Cambrian (∼529–514 Ma): Implications for biota-environment co-evolution. Earth and Planetary Science Letters 2016, 441, 38–51. 10.1016/j.epsl.2016.02.019. [DOI] [Google Scholar]
  33. Zhang Y.; He Z.; Jiang S.; Gao B.; Liu Z.; Han B.; Wang H. Marine redox stratification during the early Cambrian (ca. 529–509 Ma) and its control on the development of organic-rich shales in Yangtze Platform. Geochemistry, Geophysics, Geosystems 2017, 18 (6), 2354–2369. 10.1002/2017GC006864. [DOI] [Google Scholar]
  34. Liu Z. H.; Zhuang X. G.; Teng G. E.; Xie X. M.; Yin L. M.; Bian L. Z.; Feng Q. L.; Algeo T. J. the Lower Cambrian Niutitang Formation at Yangtiao (Guizhou, SW China): Organic Matter Enrichment, Source Rock Potential, and Hydrothermal Influences. Journal of Petroleum Geology 2015, 38 (4), 411–432. 10.1111/jpg.12619. [DOI] [Google Scholar]
  35. Yeasmin R.; Chen D.; Fu Y.; Wang J.; Guo Z.; Guo C. Climatic-oceanic forcing on the organic accumulation across the shelf during the Early Cambrian (Age 2 through 3) in the mid-upper Yangtze Block, NE Guizhou, South China. Journal of Asian Earth Sciences 2017, 134, 365–386. 10.1016/j.jseaes.2016.08.019. [DOI] [Google Scholar]
  36. Zhang Y.; Pufahl P. K.; Du Y.; Chen G.; Liu J.; Chen Q.; Wang Z.; Yu W. Economic phosphorite from the Ediacaran Doushantuo Formation, South China, and the Neoproterozoic-Cambrian Phosphogenic Event. Sedimentary Geology 2019, 388, 1–19. 10.1016/j.sedgeo.2019.05.004. [DOI] [Google Scholar]
  37. Liu Z. R. R.; Zhou M. F. Early Cambrian ocean mixing recorded by phosphorite successions in the Nanhua Basin, South China. Precambrian Research 2020, 349, 105414 10.1016/j.precamres.2019.105414. [DOI] [Google Scholar]
  38. Xiao C. Y.; Zhang Z. W.; He C. Z.; Wen H. J.; Fan H. F. The Depositional Environment of Ediacaran Phosphorite Deposits, South China. Bulletin of Mineralogy, Petrology and Geochemistry 2018, 37 (01), 121–138. [Google Scholar]; (Chinese with English abstract)
  39. Condon D.; Zhu M.; Bowring S.; Wang W.; Yang A.; Jin Y. U-Pb ages from the Neoproterozoic Doushantuo Formation, China. Science 2005, 308 (5718), 95–98. 10.1126/science.1107765. [DOI] [PubMed] [Google Scholar]
  40. Zhu B.; Jiang S. Y.; Yang J. H.; Pi D.; Ling H. F.; Chen Y. Q. Rare earth element and Sr-Nd isotope geochemistry of phosphate nodules from the lower Cambrian Niutitang Formation, NW Hunan Province, South China. Palaeogeography, Palaeoclimatology, Palaeoecology 2014, 398, 132–143. 10.1016/j.palaeo.2013.10.002. [DOI] [Google Scholar]
  41. Gao Y.; Zhang X.; Zhang G.; Chen K.; Shen Y. Ediacaran negative C-isotopic excursions associated with phosphogenic events: Evidence from South China. Precambrian Research 2018, 307, 218–228. 10.1016/j.precamres.2018.01.014. [DOI] [Google Scholar]
  42. Cremonese L.; Shields-zhou G. A.; Struck U.; Ling H.; Och L. M. Nitrogen and organic carbon isotope stratigraphy of the Yangtze Platform during the Ediacaran-Cambrian transition in South China. Palaeogeography, Palaeoclimatology, Palaeoecology 2014, 398, 165–186. 10.1016/j.palaeo.2013.12.016. [DOI] [Google Scholar]
  43. Zhang J.; Fan T.; Algeo T. J.; Li Y.; Zhang J. Paleo-marine environments of the Early Cambrian Yangtze Platform. Palaeogeography, Palaeoclimatology, Palaeoecology 2016, 443, 66–79. 10.1016/j.palaeo.2015.11.029. [DOI] [Google Scholar]
  44. Muscente A. D.; Hawkins A. D.; Xiao S. Fossil preservation through phosphatization and silicification in the Ediacaran Doushantuo Formation (South China): A comparative synthesis. Palaeogeography, Palaeoclimatology, Palaeoecology 2015, 434, 46–62. 10.1016/j.palaeo.2014.10.013. [DOI] [Google Scholar]
  45. Yang H.; Xiao J.; Xia Y.; Xie Z.; Tan Q.; Xu J.; Guo H.; He S.; Wu S. Origin of the Ediacaran Weng’an and Kaiyang phosphorite deposits in the Nanhua basin, SW China. Journal of Asian Earth Sciences 2019, 182, 103931 10.1016/j.jseaes.2019.103931. [DOI] [Google Scholar]
  46. Zhu B.; Jiang S. Y. A LA-ICP-MS analysis of rare earth elements on phosphatic grains of the Ediacaran Doushantuo phosphorite at Weng’an, South China: implication for depositional conditions and diagenetic processes. Geological Magazine 2017, 154, 1381–1397. 10.1017/S001675681700022X. [DOI] [Google Scholar]
  47. Ding Y. L.; Xie H. Research into the geochemical characteristics phosphorites of Dengying formation in the area of Weng’an county, Guizhou. China Mining Magazine 2015, 24 (08), 84–88. [Google Scholar]; (Chinese with English abstract)
  48. Sperling E. A.; Wolock C. J.; Morgan A. S.; Gill B. C.; Kunzmann M.; Halverson G. P.; Macdonald F. A.; Knoll A. H.; Johnston D. T. Statistical analysis of iron geochemical data suggests limited late Proterozoic oxygenation. Nature 2015, 523 (7561), 451–454. 10.1038/nature14589. [DOI] [PubMed] [Google Scholar]
  49. Gao P.; Liu G.; Jia C.; Young A.; Wang Z.; Wang T.; Zhang P.; Wang D. Redox variations and organic matter accumulation on the Yangtze carbonate platform during Late Ediacaran-Early Cambrian: Constraints from petrology and geochemistry. Palaeogeography, Palaeoclimatology, Palaeoecology 2016, 450, 91–110. 10.1016/j.palaeo.2016.02.058. [DOI] [Google Scholar]
  50. Och L. M.; Shields-Zhou G. A.; Poulton S. W.; Manning C.; Thirlwall M. F.; Li D.; Chen X.; Ling H.; Osborn T.; Cremonese L. Redox changes in Early Cambrian black shales at Xiaotan section, Yunnan Province, South China. Precambrian Research 2013, 225, 166–189. 10.1016/j.precamres.2011.10.005. [DOI] [Google Scholar]
  51. Li C.; Cheng M.; Algeo T. J.; Xie S. C. A theoretical prediction of chemical zonation in early oceans (>520 Ma). Science China Earth Sciences 2015, 58 (11), 1901–1909. 10.1007/s11430-015-5190-7. [DOI] [Google Scholar]
  52. Wei w.; Chen X.; Ling H. F.; Wu F.; Dong L. H.; Pan S.; Jing Z.; Huang F. Vanadium isotope evidence for widespread marine oxygenation fromthe late Ediacaran to early Cambrian. Earth and Planetary Science Letters 2023, 602, 117942 10.1016/j.epsl.2022.117942. [DOI] [Google Scholar]
  53. Wei W.; Zeng Z.; Shen J.; Tian L. L.; Wei G. Y.; Ling H. F.; Huang F. Dramatic changes in the carbonate-hosted barium isotopic compositions in the Ediacaran Yangtze platform. Geochim. Cosmochim. Acta 2021, 299 (1), 113–129. 10.1016/j.gca.2021.02.026. [DOI] [Google Scholar]
  54. Zhu M.; Lu M.; Zhang J.; Zhao F.; Li G.; Aihua Y.; Zhao X.; Zhao M. Carbon isotope chemostratigraphy and sedimentary facies evolution of the Ediacaran Doushantuo Formation in western Hubei, South China. Precambrian Research 2013, 225, 7–28. 10.1016/j.precamres.2011.07.019. [DOI] [Google Scholar]
  55. Qiao W.; Lang X.; Peng Y.; Jiang K.; Chen W.; Huang K.; Shen B. Sulfur and oxygen isotopes of sulfate extracted from early Cambrian phosphorite nodules: implications for marine redox evolution in the Yangtze platform. Journal of Earth Science 2016, 27 (2), 170–179. 10.1007/s12583-016-0688-2. [DOI] [Google Scholar]
  56. Li M. H. Evaluation of paired carbon isotopic signals from the Ediacaran Doushantuo phosphorites: diagenetic or primary?. Precambrian Research 2020, 349, 105502 10.1016/j.precamres.2019.105502. [DOI] [Google Scholar]
  57. Qin Z.; Xu D.; Kendall B.; Zhang X.; Ou Q.; Wang X.; Li J.; Liu J. Molybdenum isotope-based redox deviation driven by continental margin euxinia during the early Cambrian. Geochim. Cosmochim. Acta 2022, 325, 152–169. 10.1016/j.gca.2022.03.007. [DOI] [Google Scholar]
  58. Chen F.; Ding H. B.; Zheng; M R. Geochemical characteristics of trace elements in the Tuanshanpu uranium-bearing phosphorite deposit, Guizhou. Nonferrous Metals Design 2017, 44 (04), 25–28. [Google Scholar]; (Chinese with English abstract)
  59. Wang Q.; Xu J. H.; Wu L. F.; Wu C. Q.; Peng S.; Li X. Y.; Jin Z. R.; Fan Y. F.; Lu P. Petrogeochemical characteristics of phosphorite-type uranium deposits in Tongren area, eastern Guizhou. Uranium Geology 2022, 38 (06), 1137–1151. [Google Scholar]
  60. Chi Q., Yan M.. Handbook of elemental abundance for applied geochemistry.; Geological Publishing House, Beijing China, 2007. [Google Scholar]
  61. Wu K.; Ma D. S.; Pan J. Y.; Zhou J.; Xia F.; Liu L. The geochemistry of phosphorite of Doushantuo Formation in Weng’an, China: Insights from trace elements and REE. Journal of East China University of Technology (Natural Science) 2006, 02, 108–114. [Google Scholar]; (Chinese with English abstract)
  62. Wen H.; Carignan J.; Zhang Y.; Fan H.; Cloquet C.; Liu S. Molybdenum isotopic records across the Precambrian-Cambrian boundary. Geology 2011, 39 (8), 775–778. 10.1130/G32055.1. [DOI] [Google Scholar]
  63. Zhu G.; Wang P.; Li T.; Zhao K.; Yan H.; Li J.; Zhou L. Nitrogen geochemistry and abnormal mercury enrichment of shales from the lowermost Cambrian Niutitang Formation in South China: Implications for the marine redox conditions and hydrothermal activity. Global and Planetary Change 2021, 199, 103449 10.1016/j.gloplacha.2021.103449. [DOI] [Google Scholar]
  64. Liu Z. R. R.; Zhou M. F. Meishucun phosphorite succession (SW China) records redox changes of the early Cambrian ocean. Bulletin of the Geological Society of America 2017, 129 (11–12), 1554–1567. 10.1130/B31612.1. [DOI] [Google Scholar]
  65. Shi C. H.Formation of phosphorite deposit, break up of Rodinia supercontinent and biology explosion- A case study of Weng’an, Kaiyang and Zhijin phosphorite deposits of Guizhou province. The Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou Province, China, 2005. (Chinese with English abstract). [Google Scholar]
  66. Wang Z. G., Yu X Y.. Geochemistry of rare earth elements.; Science Publishing House, 1989. [Google Scholar]
  67. Zheng W. Z.; Dongye M. X.; Hu L. L. REE geochemistry of phosphorite from the Doushantuo Formation of the Zhandan period in western Hubei. Geological Review 1992, 38 (04), 352–359. [Google Scholar]
  68. Gómez-Peral L. E.; Kaufman A. J.; Poiré D. G. Paleoenvironmental implications of two phosphogenic events in Neoproterozoic sedimentary successions of the Tandilia System, Argentina. Precambrian Research 2014, 252, 88–106. 10.1016/j.precamres.2014.07.009. [DOI] [Google Scholar]
  69. Huang T. Z.; Wang R. M.; Shen B. Phosphorus cycle and biological pump in the Middle-aged Earth: a further discussion on the Silence of a billion years. Chin. Sci. Bull. 2022, 67 (15), 1614–1623. 10.1360/TB-2021-1168. [DOI] [Google Scholar]
  70. Zhegallo E. A. On the biogenic origin of phosphorites. Paleontological Journal 2016, 50 (12), 1331–1338. 10.1134/S0031030116120212. [DOI] [Google Scholar]
  71. Brock J.; Schulz-Vogt H. N. Sulfide induces phosphate release from polyphosphate in cultures of a marine Beggiatoa strain. ISME Journal 2011, 5 (3), 497–506. 10.1038/ismej.2010.135. [DOI] [PMC free article] [PubMed] [Google Scholar]
  72. Wang R.; Ding W.; Zhang Y.; Wang Z.; Wang X.; He J.; Zeng W.; Dai P. Analysis of developmental characteristics and dominant factors of fractures in Lower Cambrian marine shale reservoirs: A case study of Niutitang formation in Cen’gong block, southern China. J. Pet. Sci. Eng. 2016, 138, 31–49. 10.1016/j.petrol.2015.12.004. [DOI] [Google Scholar]
  73. Liu X. Q.; Zhang H.; Tang Y.; Liu Y. L. Effect of hydrothermal process on phosphorite type REE deposit in Zhijin, Guizhou: evidence from fluid inclusions. Acta Mineralogica Sinica 2019, 39 (04), 403–411. [Google Scholar]; (Chinese with English abstract)
  74. Li D.; Ling H. F.; Jiang S. Y.; Pan J. Y.; Chen Y. Q.; Cai Y. F.; Feng H. Z. New carbon isotope stratigraphy of the Ediacaran-Cambrian boundary interval from SW China: Implications for global correlation. Geological Magazine 2009, 146 (4), 465–484. 10.1017/S0016756809006268. [DOI] [Google Scholar]
  75. Guo Q. J.; Yang W. D.; Liu C. Q.; Harald S.; Wang X. L.; Zhao Y. L. Sedimentary Geochemical study on the formation of Weng’an Biota and Phosphate Ore in Guizhou. Bulletin of Mineralogy, Petrology and Geochemistry 2003, 22 (03), 202–208. [Google Scholar]

Articles from ACS Omega are provided here courtesy of American Chemical Society

RESOURCES