1-2 时空中的地球.ppt

1、环境地质学 Environmental Geology,环境地质学Environmental Geology,主讲人：万新南教授 Prof. Wan xinnan,第一讲,环境地质学 Environmental Geology,2、时空中的地球 Earth in Space and Time,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,1）早期的太阳系 The Early Solar System Billions of years ago, out of a swirling mass of gas and dust, evolved a sy

2、stem of varied planets hurtling around a nuclear-powered star-our solar system. One of these planets, and one only, give rise to complex life forms. Over time, a tremendous diversity of life forms and ecological system developed, while the planet too evolved and changed, its interior churning搅拌, its

3、 landmasses shifting漂移, its surface constantly being reshaped,环境地质学 Environmental Geology,2、时空中的地球 Earth in Space and Time,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,1）、早期的太阳系 The Early Solar System Billions of years ago, out of a swirling mass of gas and dust, evolved a system of varied planets

4、hurtling around a nuclear-powered star-our solar system. One of these planets, and one only, give rise to complex life forms. Over time, a tremendous diversity of life forms and ecological system developed, while the planet too evolved and changed, its interior churning搅拌, its landmasses shifting漂移,

5、 its surface constantly being reshaped,环境地质学 Environmental Geology,2、时空中的地球 Earth in Space and Time,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,2）九大行星的形成The planets The compositions of the planets formed depended largely on how near they were to the hot sun. The planets formed nearest to the sun c

6、ontained mainly high-temperature materials: metallic iron and a few minerals with very high melting temperatures, with little water or gas. Somewhat farther out, where temperatures were lower, the developing planets incorporated much larger amounts of lower-temperature minerals, including some that

7、contain water locked within their crystal structures. (This development later made it possible for the earth to have liquid water at its surface.) Still farther from the sun, temperatures were so low that nearly all of the materials in the original gas cloud condensedeven materials like methane and

8、ammonia, which are gases at normal earth surface temperatures and pressures.,环境地质学 Environmental Geology,2、时空中的地球 Earth in Space and Time,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,3、地球与其它星体的比较,环境地质学 Environmental Geology,2、时空中的地球 Earth in Space and Time,第一部分：宇宙与地球 Chapter 1:Our Planetry Environm

9、ent,4）、地球的结构与组成,环境地质学 Environmental Geology,4）地球的构造与组成,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,2、时空中的地球 Earth in Space and Time,环境地质学 Environmental Geology,5）地球的演化 Earth, then and now,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,A、(地球的初始无序形态：无海洋、无大气） The early earth was very different from wh

10、at it is today, lacking the modern oceans and atmosphere and having a much different surface from its present one, probably more closely resembling the barren, cratered surface of the moon. The planet was heated by several processes: the impact of the colliding dust particles and meteorites as they

11、came together to form the earth, compression of the interior by gravity (that materials heat up when compressed can be demonstrated by pumping up a bicycle tire and then feeling the barrel of the pump), and energy release from decay of the small amounts of several naturally radioactive elements that

12、 the earth contains.,环境地质学 Environmental Geology,5）地球的演化 Earth, then and now,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,B、(地球的初始无序形态三类热源、使之熔化、分异） These three heat sources combined to raise the earths internal temperature enough that parts of it, perhaps eventually most of it, melted, although it

13、was probably never molten all at once. Dense materials, like metallic iron, would have tended to sink toward the middle of the earth. As cooling progressed, lighter, low-density mineral crystallized and floated out toward the surface. The eventual result was an earth differentiated into several majo

14、r compositional zones; the central core; the surrounding mantle; and a thin crust at the surface (fig1.1.1). The process was complete before 4 billion years ago.（四十亿年前）,环境地质学 Environmental Geology,5）地球的演化 Earth, then and now,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,C、早期大气层的形成（The earths early a

15、tmosphere） quite different from the modern one, aside from the effects of modern pollution. （1）、（无大气层、缺氧）The first atmosphere had little or no free oxygen in it. It probably consisted dominantly of nitrogen and carbon dioxide ( the gas most commonly released from volcanoes, aside from water) with mi

16、nor amounts of such gases as methane, ammonia, and various sulfur gases. （2）、（人类不能生存）Humans could not have survived in this early atmosphere. （3）、（藻类造氧说）Oxygen-breathing life of any kind could not exist before the first simple plants-the single-celled blue-green algae藻-appeared in large numbers to m

17、odify the atmosphere. Their remains are found in rocks several billion years old. They manufacture food by photosynthesis, using sunlight for energy, consuming carbon dioxide, and releasing oxygen as a by-product. In time, enough oxygen accumulated that the atmosphere could support oxygen-breathing

18、organisms.,环境地质学 Environmental Geology,5）地球的演化 Earth, then and now,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,D、地球与地球表面岩石年龄的确定 （1）、Arranging Events in Order （事件排序法） （2）、Correlation Fossils play a role in the determination or relative ages, too. The concept that fossils could be the remains of old

19、er life forms dates back at least to the ancient Greeks, but for some time it fell out of favor不再、失去. The idea was seriously revived复苏 in the 1700s, and around the year 1800, William Smith put forth the Law of Faunal Succession（生物层序法）. (3)、Uniformitarianism Geologic processes were the focus of anoth

20、er early worker-the physician, farmer, and part-time geologist James Hutton. Hutton is widely credited with developing and popularizing the concept of uniformitarianism均变说. Uniformitarianism is sometimes described briefly by the phrase“the present is the key to the past.” （均变说）,环境地质学 Environmental G

21、eology,5）地球的演化 Earth, then and now,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,D、地球与地球表面岩石年龄的确定 （4）、 Radioactive Decay and DatingAs noted above, one key property of any particular radioisotope is that it decays at a constant, characteristic rate, with a distinct half-life, which can be determined

22、in the laboratory. One can then, in principle, use the relative amounts of a decaying isotope (parent) and the product isotope into which it decays (daughter) to find the age of the sample. Fig.A.7 illustrates the fundamental idea. Suppose that parent isotope A decays to daughter B with a half-life

23、of 1 million years. （放射性测年） （5）、Radiometric and Relative Ages Combined Radiometric dates放射性测年 (dates determined using radioisotopic methods) are sometimes imprecisely called “absolute” ages to distinguish them from the relative ages determined as described earlier. For various reasons, accurate radi

24、ometric dates cannot be determined for many rocks and fossils, so “absolute” and relative dating methods are often used in conjunction. （放射性测年与相对年龄法结合）,环境地质学 Environmental Geology,E、地质时代表 Geologic time,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,5）地球的演化 Earth, then and now,环境地质学 Environmental Geol

25、ogy,4）地球上的生物演化Earth, then and now,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,环境地质学 Environmental Geology,3、人口Nature and Rate of Population Growth,Growth Rates: Causes and Consequences Growth Rate and Doubling Time,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,环境地质学 Environmental Geology,3、人口Natur

26、e and Rate of Population Growth,世界总人口与人口分布 亚洲与中国人口,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,环境地质学 Environmental Geology,3、人口Nature and Rate of Population Growth,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,环境地质学 Environmental Geology,4、地球物质的化学组成Rock and Minerals in earth,第一部分：宇宙与地球 Chapter 1:O

27、ur Planetry Environment,Atomic Structure All natural and most synthetic substances on earth are made from the ninety naturally occurring chemical elements. An atom is the smallest particle into which an element can be divided while still retaining the chemical characteristics of that element (fig 3.

28、1). The nucleus, at the center of the atom, contains one or more particles with a positive electrical charge (protons质子) and usually some particles of similar mass that have no charge (neutrons中子). Circling the nucleus核 are the negatively charged electrons.,环境地质学 Environmental Geology,4、地球物质的化学组成Roc

29、k and Minerals in earth,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,环境地质学 Environmental Geology,4、地球物质的化学组成Rock and Minerals in earth,第一部分：宇宙与地球 Chapter 1:Our Planetry Environment,Elements and Isotopes 4.With the exception of the simplest hydrogen atoms, all nuclei contain neutrons, and the number

30、 of neutrons is similar to or somewhat greater than the number of protons. The number of neutrons in atoms of one element is not always the same. The sum of the number of protons and the number of neutrons in a nucleus is the atoms atomic mass number. Atoms of a given element with different atomic m

31、ass numbersin other words, with the same number of protons but different numbers of neutronsare distinct isotopes of that element. Some elements have only a single isotope, while others may have ten or more. (The,环境地质学 Environmental Geology,4、地球物质的化学组成Rock and Minerals in earth,第一部分：宇宙与地球 Chapter 1:

32、Our Planetry Environment,Chemical Symbols 8. Each chemical element is denoted by a one-or two-letter symbol. Many of these symbols make sense in terms of the English name for the element-O for oxygen, He for helium, Si for silicon, and so on. Other symbols reflect the fact that, in earlier centuries

33、, scientists were generally versed in Latin or Greek: The symbols Fe for iron and Pb for lead, for example, and derived from ferrum and plumbum, respectively, the Latin names for these elements.,环境地质学 Environmental Geology,4、地球物质的化学组成Rock and Minerals in earth,第一部分：宇宙与地球 Chapter 1:Our Planetry Envir

34、onment,Minerals Defined 11. A mineral is naturally occurring, inorganic, solid element or compound with a definite chemical composition and a regular internal crystal structure. Naturally occurring, as distinguished from synthetic, means that minerals do not include the thousands of chemical substan

35、ces invented by humans. Inorganic means not produced solely by living organisms or by biological processes. That minerals must be solid means that the ice of a glacier is a mineral, but liquid water is not. Chemically, minerals may consist either of one element-like diamonds, which are pure carbon-or t