1、 Sedimentary Geochemistry Review of the course Spring semester 2015-2016 Institute of Geochemistry School of Earth and Space Sciences Peking University Qiugen Li Course Time: 10:10-12:00 Pm, Tues. Place: RM 3522, New Geological Building Qiugen Li Office: RM 3508 Tel: 17710232876 Email: Sedimentary G
2、eochemistry Syllabus (一一) 1) This is the course concerning the chemical composition of sediments and sedimentary rocks, which may be interpreted in terms of sediment provenance and sedimentary processes, including weathering, transport, deposition and diagenesis. These processes can impact sediment
3、chemistry. 2) In turn, chemical records left behind in sediments and sedimentary rocks that provide information to be used to better understand basin analysis, paleoclimates, and crustal evolution. 3) Finally, tectonic setting of sedimentary basin will be examined in detail. Syllabus （二）（二） There is
4、 no textbook for this course none has been written. 1) Garrels and Christ (1965, Solutions, Minerals and Equilibria) and Degens (1965, Geochemistry of Sediments) are still good choices for obtaining many of the basic principles. 2) Multi-authored volumes that focus on the topics at hand (for terrest
5、rial settings) include those edited by Johnsson and Basu (1993), Rollinson (1993), Lentz (2003) and Arribas (2007), which builds upon the work of Taylor and McLennan (1985) and others (such as Shaw et al., 1954, 1956, 1967, Berner, 1971, Gromet et al., 1984). 3) Boggs (2009) in his book “Petrology o
6、f Sedimentary rocks” focused on application of insights derived from study of rock properties to interpretation of their origin, including Provenance, depositional environments and diagenesis. Syllabus （二）（二） There is no textbook for this course none has been written. In order to evaluate the compos
7、ition of sedimentary rocks, a basic understanding of geochemistry (both elemental and isotopic) is needed. Additionally, familiarity with the central tenets of physical geology, sedimentology and tectonics of sedimentary basin is recommended. Some of this background will be provided and more detail
8、can be found in a most general geochemistry texts. The free online textbook by Bill White (2010) is very comprehensive and has the added advantage of a terrific price. Although not a low-temperature geochemistry course, a number of basic concepts from this field will also be covered. A good textbook
9、 by Konrad B. Krauskopf and Dennis K. Bird (1995): Introduction to Geochemistry，is also worthy. Syllabus （三）（三） Audience (Anyone interested): graduate students. Instructing (teacher) and Reading (students). Reading Report. Sedimentary Geochemistry Processes that produce sedimentary rocks are less my
10、sterious than those that form the igneous and metamorphic rocks, because many of these processes can be observed. Sedimentary rocks and sediments are widely distributed over the surface of the earth. Although sedimentary rocks make up only 0.029% of the total volume of the earth, they represent abou
11、t two-thirds of the exposed rocks of the land surface. Boggs (2009) Rivers, oceans, winds, and rain runoff all have the ability to carry the particles washed off of eroding rocks. Such material, called detritus, consists of fragments of rocks and minerals. When the energy of the transporting current
12、 is not strong enough to carry these particles, the particles drop out in the process of sedimentation. This type of sedimentary deposition is referred to as clastic sedimentation. Another type of sedimentary deposition occurs when material is dissolved in water, and chemically precipitates from the
13、 water. This type of sedimentation is referred to as chemical sedimentation. A third process can occur, wherein living organisms extract ions dissolved in water to make such things as shells and bones. This type of sedimentation is called biogenic sedimentation. Thus, there are three major types of
14、sedimentary rocks: Clastic sedimentary rocks, Chemical sedimentary rocks, and biogenic sedimentary rocks. Boggs (2009) 海洋除海岸附近及表层 海水较动荡外，绝大部 分海域中的水体均处于 相对静止状态，海洋是 地球表面最大的积水盆 地和沉积场所。 滨海带的沉积：海滩、 沙坝和泻湖 浅海带（最重要的沉积 区）：机械、化学和生 物沉积 半深海、深海：软泥、 浊流和锰结核等 Li and Schoonmaker （2014） Riboulleau et al.（2014） Boggs
15、(2009) Leeder (2011) Tectonic Sedimentology Sandstone Cawood et al. (2012) Sedimentary Geochemistry Sedimentary Geochemistry Sedimentary Geochemistry Rollison (1993) 1. The geochemistry of sedimentary rocks is controlled by a number of factors, which can include: 2. The first step in analyzing geoch
16、emical data should be an investigation of the factors which controlled the concentrations of each element in the data set; 3. Identifying the elements which have concentrations primarily dependent on source area composition allows their use in matching the sediments to a discrete source area or char
17、acterizing the general type of source terrain which shed the detritus. Sedimentary Geochemistry Implications Geologic relations that help establish the timing of terrane amalgamation and accretion Cawood et al. (2009) The two main aspects of climate are temperature and precipitation, but, locally, w
18、ind regimes may also be significant. Not only are mean annual temperature and precipitation important, but also their fluctuations, both seasonal and non-seasonal, and their magnitude and frequency of extreme events. According to Tricart and Cailleux (1972), eight morphoclimatic regions are defined.
19、 The classification is based on 1) mean annual temperature; 2 ) M e a n a n n u a l precipitation; 3) Mean number of wet months; 4) mean temperature of the warmest month. Sedimentary Geochemistry Sedimentary Geochemistry Sedimentary Geochemistry Sageman and Lyons （2003） General lecture topics and re
20、ading/reporting schedule The course is divided up into 10 Topics, each of which will last anywhere from about one class to several classes. Topic 0: Reviews of the Course Topic 1: Introduction Topic 2: Basics of Sedimentary Geochemistry including Major and trace elements Topic 3: Radiogenic isotopes
21、 Topic 4: Sedimentary Processes 1: Weathering Topic 5: Sedimentary Processes 2: Transport, Diagenesis and Sedimentary Recycling Topic 6: Diagenetical minerials and Dating Topic 7: Provenance and detrital Analysis Topic 8: Provenance and Component Analysis Topic 9: Sedimentary Geochemistry and Crusta
22、l Evolution Sedimentary Geochemistry Introduction In this part, we will briefly introduce composition of continental crust and growth, aquatic chemistry and residence time. This introduction will also give an overview about some of our approaches to sedimentary geochemistry on Earth. Finally, we wil
23、l cover the comparisons between the differing approaches of sedimentary and igneous geochemistry and why it is important to have a basic understanding of igneous geochemistry. The purpose of this topic is to introduce you to the most important techniques used to evaluate geochemical data for sedimen
24、tary rocks. We will review some basic principles including partition coefficients and formal definitions of trace elements, intermediate elements and essential structural constituents. We will also introduce a very useful way to evaluate major element data using two ternary diagrams, one especially
25、useful for granitic systems and the other for basaltic systems. Finally, some time will be spent reviewing trace element data for sedimentary rocks, concentrating on the rare earth elements (REE) that are considered especially useful for evaluating the provenance of sedimentary rocks. Here the focus
26、 will be on why certain elements are more useful for evaluating sedimentary provenance versus whereas others are more useful for evaluating various sedimentary processes (weathering, sorting, diagenesis, etc.). Basics of Sedimentary Geochemistry including Major and trace elements Radiogenic Isotopes
27、 In these lectures we will examine systematics of radiogenic isotopes and describe some applications to understand questions of sedimentary process and provenance. We will focus on Sr, Nd, Pb, Hf and Ar isotopes. We will quickly run through the decay equations as they apply to one parent one daughte
28、r (e.g., Rb/Sr), one parent two daughter (e.g., K-Ar) and two parent two daughter (e.g., U-Pb) systems. After going through the decay equations, we will address the isotope systems in order of Nd, Sr, Hf, Ar and Pb, in the latter case considering both common Pb (e.g., feldspar) and radiogenic Pb (e.
29、g., zircon dating) approaches. In general, we will consider how isotopic data can be used for dating sedimentary materials (both provenance and process) and as tracers of sediment sources. WeatheringWeathering This part will consider chemical weathering. The approach contrasts greatly with classical
30、 treatments of weathering which focus on individual mineral reaction pathways and kinetics. We will begin with a discussion of terrestrial weathering processes and how mineralogical transformations are dominated by oxidation and acid-base reactions. We will then define the Chemical Index of Alterati
31、on (CIA) and how this weathering index ties in to A-CN-K diagrams. Next we will discuss the approaches taken to evaluate absolute elemental losses and gains during weathering processes that fundamentally involve mass losses (and locally mass gains). Next we will consider how basaltic rock weathering
32、 can be evaluated using A-CNK-FM relationships. Sedimentary Processes: Transport, Diagenesis, and Sedimentary Recycling In this section, we will address three additional sedimentary processes, transport (sorting), diagenesis and sedimentary recycling, that can influence the chemical and isotopic com
33、position of sedimentary rocks. First, we will examine how transport processes, when acting on weathered products (primary minerals and secondary clays), can have a significant influence on major element geochemistry of sediments, as seen on both A-CN-K and A-CNK-FM diagrams. Fractionation of heavy m
34、inerals and their concentration in sand and silt size fractions are common processes resulting from size/density differences. A comprehensive evaluation of the geochemistry of diagenesis is far beyond the scope of this course. Diagenetic REE mobility (involving dissolution of soluble phosphate miner
35、als) and resetting of the Nd isotope system in early Paleozoic turbidites and black shales will be examined. Finally, we will look at how the process of sedimentary recycling can influence both trace element and Nd-isotopic relationships in sedimentary rocks. Diagenetical minerials and Dating This p
36、art will introduce some diagenetical minerials and using these new minerials gives the true depositional age. Provenance and Component AnalysisProvenance and Component Analysis Because of the development of rapid, in situ analytical methods (both chemical and isotopic), there has been an increasing
37、tendency to evaluate sediment provenance on a “grain by grain” basis in order to establish the distribution and relative importance of the various provenance components. However, in doing so one must face a series of geological and statistical issues bias and representatives in the minerals chosen f
38、or analysis, nature of age distributions (normal vs. non-normal), detection limits, uncertainties, and so forth. In this section, we will briefly review some of the chemical and isotopic approaches to “component analysis”. An important point that will be emphasized is the possible difference in prov
39、enance information that comes from the study of major framework components (quartz and feldspar), minor components (notably zircon) and whole-rock geochemistry. We will then briefly review some of the statistical considerations in interpreting detrital mineral age distributions. Paleoclimates, Crust
40、al Evolution and Plate TectonicsPaleoclimates, Crustal Evolution and Plate Tectonics In this lecture We will begin with a discussion of sediment composition and paleoclimate. Using CIA stratigraphy evaluates major climate shifts and constrains global atmospheric paleocirculation patterns. The notion
41、 that sedimentary rocks provide an efficient averaging of the upper continental crust has been a mainstay of crustal geochemistry. We will examine secular variations in sediment composition and how this can be used to constrain models of crustal evolution on Earth. Understanding the relationships be
42、tween plate tectonic association and sediment composition cover this part in the end. The basic point here will be that much geochemical information and insight can be obtained that is relevant to tectonic conditions and associations but caution is warranted when trying to use geochemistry for tecto
43、nic discrimination. Sedimentary Geochemistry Important Journals concerning Important Journals concerning “Sedimentary Geochemistry Sedimentary Geochemistry ” 1. Geochimica et Cosmochimica Acta 2. Chemical Geology 3. Applied Geochemistry 4. Sedimentary Geology 5. Sedimentology 6. Journal of Sedimenta
44、ry Research 7. Palaeogeography, Palaeoclimatology, Palaeoecology 8. Environmental Geosciences 9. Marine and Petroleum Geology 10. Journal Petroleum Geology 11. Petroleum Geoscience 12. American Association of Petroleum Geologists Bulletin 13. Bulletin of Canadian Petroleum Geology and so on Sediment
45、ary Geochemistry Introduction Spring semester 2015-2016 Institute of Geochemistry School of Earth and Space Sciences Peking University Qiugen Li Office: RM 3508 Tel: 13671352603 Email: Sedimentary Geochemistry Introduction In this part, we will briefly introduce 1) composition of continental crust a
46、nd growth, 2) aquatic chemistry and 3) residence time. This Introduction will also give an overview about 4) some of our approaches to sedimentary geochemistry on Earth. Finally, we will cover 5) the comparisons between the differing approaches of sedimentary and igneous geochemistry and why it is i
47、mportant to have a basic understanding of igneous geochemistry. 1. 研究的对象：研究的对象： 2. 什么是沉积地球化学：什么是沉积地球化学： 沉积地球化学是一门沉积学与地球化学相互渗透、相互结合而沉积地球化学是一门沉积学与地球化学相互渗透、相互结合而 产生的产生的新兴边缘学科新兴边缘学科。是以沉积物和沉积岩为对象。是以沉积物和沉积岩为对象, , 研究其研究其 在沉积、成岩过程中所含元素及稳定同位素的在沉积、成岩过程中所含元素及稳定同位素的迁移、聚集与迁移、聚集与 分布分布规律，进而阐明沉积物（岩）的物质来源和分异机制以规律，进而
48、阐明沉积物（岩）的物质来源和分异机制以 及确定其沉积时及确定其沉积时的古环境和构造背景的古环境和构造背景。 3 3 研究内容广泛：研究内容广泛： 1) 1) 研究沉积过程中物质的研究沉积过程中物质的 化学运动和变化过程；化学运动和变化过程； 2) 2) 研究控制和影响元素和研究控制和影响元素和 同位素变化的各种因素。同位素变化的各种因素。 4. 沉积地球化学的演化和当前的研究进展。沉积地球化学的演化和当前的研究进展。 1) 最早最早分析和汇编沉积岩地球化学数据的，当属分析和汇编沉积岩地球化学数据的，当属Clark(1924)和和 Goldschmidt (1954); 2) Shaw（1954
49、a,b, 1956）泥质岩地球化学论文的发表，堪称是拉开了）泥质岩地球化学论文的发表，堪称是拉开了 沉积地球化学研究的沉积地球化学研究的序幕序幕; 3) Degens（1965）的Geochemistry of Sediments: A Brief History、 Garrels 4. 沉积地球化学的演化和当前的研究进展沉积地球化学的演化和当前的研究进展 4) 发展及发展趋势：发展及发展趋势： 发展：发展：The Continental Crust: Its Composition and Evolution(Taylor, 1985)； Processes Controlling the Composition of Clastic Sediments(Johnsson, 1993), Bhatia及其合作者的一系列发表论文, 以及Sediments, Diagenesis, and Sedimentary rocks (Mackenzie, 2003)和Geochemistry of Sediments and Sedimentary Rocks: Evolutionary Considerations to Mineral Deposit- Forming Environments (Lentz, 2003); Heavy minerals in use (Mange
