Extraterrestrial cause for the Cretaceous-Tertiary extinction. (Record no. 51988)
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| 000 -LEADER | |
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| fixed length control field | 02178nam a2200217Ia 4500 |
| 003 - CONTROL NUMBER IDENTIFIER | |
| control field | MX-MdCICY |
| 005 - DATE AND TIME OF LATEST TRANSACTION | |
| control field | 20250625160218.0 |
| 040 ## - CATALOGING SOURCE | |
| Transcribing agency | CICY |
| 090 ## - LOCALLY ASSIGNED LC-TYPE CALL NUMBER (OCLC); LOCAL CALL NUMBER (RLIN) | |
| Classification number (OCLC) (R) ; Classification number, CALL (RLIN) (NR) | B-17827 |
| 008 - FIXED-LENGTH DATA ELEMENTS--GENERAL INFORMATION | |
| fixed length control field | 250602s9999 xx |||||s2 |||| ||und|d |
| 245 10 - TITLE STATEMENT | |
| Title | Extraterrestrial cause for the Cretaceous-Tertiary extinction. |
| 490 0# - SERIES STATEMENT | |
| Volume/sequential designation | Science, 208(4448), p.1095-1108, 1980 |
| 520 3# - SUMMARY, ETC. | |
| Summary, etc. | Platinum metals are depleted in the earth's crust relative to their cosmic abundance; concentrations of these elements in deep-sea sediments may thus indicate influxes of extraterrestrial material. Deep-sea limestones exposed in Italy, Denmark, and New Zealand show iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given to indicate that this iridium is of extraterrestrial origin, but did not come from a nearby supernova. A hypothesis is suggested which accounts for the extinctions and the iridium observations. Impact of a large earth-crossing asteroid would inject about 60 times the object's mass into the atmosphere as pulverized rock; a fraction of this dust would stay in the stratosphere for several years and be distributed worldwide. The resulting darkness would suppress photosynthesis, and the expected biological consequences match quite closely the extinctions observed in the paleontological record. One prediction of this hypothesis has been verified: the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the Cretaceous and Tertiary limestones, which are chemically similar to each other. Four different independent estimates of the diameter of the asteroid give values that lie in the range 10 ± 4 kilometers. |
| 650 14 - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name entry element | THE CRETACEOUS-TERTIARY EXTINCTION |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Alvarez, L.W. |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Alvarez,W. |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Asaro, F. |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Michel, H. V. |
| 856 40 - ELECTRONIC LOCATION AND ACCESS | |
| Uniform Resource Identifier | <a href="https://drive.google.com/file/d/1x8BTNkdaK5NPR5FvYXSmA0X_EmdELehM/view?usp=drivesdk">https://drive.google.com/file/d/1x8BTNkdaK5NPR5FvYXSmA0X_EmdELehM/view?usp=drivesdk</a> |
| Public note | Para ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx |
| 942 ## - ADDED ENTRY ELEMENTS (KOHA) | |
| Source of classification or shelving scheme | Clasificación local |
| Koha item type | Documentos solicitados |
| Lost status | Source of classification or shelving scheme | Damaged status | Not for loan | Collection | Home library | Current library | Shelving location | Date acquired | Total checkouts | Full call number | Date last seen | Price effective from | Koha item type |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clasificación local | Ref1 | CICY | CICY | Documento préstamo interbibliotecario | 25.06.2025 | B-17827 | 25.06.2025 | 25.06.2025 | Documentos solicitados |