Importance of radiometric dating
Although the basic principle of radiometric dating is simple, the actual procedure is quite complex. The chemical analysis that determines the quantities of parent painstakingly and daughter must be precise. In addition, some radioactive materials do daughter product. As you saw not decay directly into the stable in Figure 11.16, uranium-238 produces l3 intermediate unstable daughter products before the 14th and final daughter product, the stable isotope lead-206, is produced.
Radiometric dating methods have produced literally thou sands of dates for events in Earth history, Rocks exceeding 3.5 billion years in age are found on all ofthe continents. Earth's oldest rocks(so far) are gneisses from northern Canada near Great Slave Lake that have been dated at 4.03 billion years(b.y.) Rocks from western Greenland have been dated at 3.7-3.8 and rocks nearly as old are found in the Minnesota River Valley and northern Michigan(3.5-3.7 b.y.), in southern Africa(3.4-3.5 b.y.), and in western Australia(3.4-3.6 b.y.). It is important to point out that these ancient rocks are not from any sort of"pri mordial crust" but originated as lava flows, igneous intrusions, and sediments deposited in shallow water-an indication that Earth history began before these rocks formed. Even older min eral grains have been dated. Tiny crystals of the mineral zircon having radiometric ages as old as 4.3 b.y. have been found younger sedimentary rocks in western Australia. The source rocks for these tiny durable grains either no longer exist or have not yet been found. Radiometric dating has vindicated the ideas of James Hutton, Charles Darwin, and others who inferred that geologic time must be immense. Indeed, modern dating methods have proved that there has been enough time for the processes we observe to have accomplished tremendous tasks.
ความสำคัญของการนับแม้ว่าหลักการเบื้องต้นของการนับเป็นอย่างง่าย ขั้นตอนจริงจะค่อนข้างซับซ้อน การวิเคราะห์สารเคมีที่กำหนดปริมาณแม่ลำบากและลูกสาวต้องแม่นยำ นอกจากนี้ บางวัสดุกัมมันตรังสีทำผลิตภัณฑ์ลูกสาว ตามที่คุณเห็นไม่ผุลงคอกในรูปที่ 11.16 ยูเรเนียม-238 ผลิตผลิตภัณฑ์ลูกกลางเสถียร l3 ก่อนผลิตผลิตภัณฑ์ 14 และสุดท้ายลูกสาว ไอโซโทปรอ-206Radiometric dating methods have produced literally thou sands of dates for events in Earth history, Rocks exceeding 3.5 billion years in age are found on all ofthe continents. Earth's oldest rocks(so far) are gneisses from northern Canada near Great Slave Lake that have been dated at 4.03 billion years(b.y.) Rocks from western Greenland have been dated at 3.7-3.8 and rocks nearly as old are found in the Minnesota River Valley and northern Michigan(3.5-3.7 b.y.), in southern Africa(3.4-3.5 b.y.), and in western Australia(3.4-3.6 b.y.). It is important to point out that these ancient rocks are not from any sort of"pri mordial crust" but originated as lava flows, igneous intrusions, and sediments deposited in shallow water-an indication that Earth history began before these rocks formed. Even older min eral grains have been dated. Tiny crystals of the mineral zircon having radiometric ages as old as 4.3 b.y. have been found younger sedimentary rocks in western Australia. The source rocks for these tiny durable grains either no longer exist or have not yet been found. Radiometric dating has vindicated the ideas of James Hutton, Charles Darwin, and others who inferred that geologic time must be immense. Indeed, modern dating methods have proved that there has been enough time for the processes we observe to have accomplished tremendous tasks.
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