کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6446603 | 1640851 | 2014 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Isotopic reconstruction of the African Humid Period and Congo Air Boundary migration at Lake Tana, Ethiopia
ترجمه فارسی عنوان
بازسازی ایزوتوپ دوره مرطوب آفریقایی و مهاجرت مرز هوایی کنگو در دریاچه تانا، اتیوپی
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کلمات کلیدی
پائول کللیمات گرمسیری، آفریقای شرقی، ایزوتوپ های هیدروژن ترکیب خاص، دوره مرطوب آفریقا، هولوسن پیلوکسلیت، مسیرهای انبساط هوا، مرز هوایی کنگو،
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
زمین شناسی
چکیده انگلیسی
The African Humid Period of the early to mid-Holocene (12,000-5000 years ago) had dramatic ecological and societal consequences, including the expansion of vegetation and civilization into the “green Sahara.” While the humid period itself is well documented throughout northern and equatorial Africa, mechanisms behind observed regional variability in the timing and magnitude of the humid period remain disputed. This paper presents a new hydrogen isotope record from leaf waxes (δDwax) in a 15,000-year sediment core from Lake Tana, Ethiopia (12°N, 37°E) to provide insight into the timing, duration, and intensity of the African Humid Period over northeastern Africa. δDwax at Lake Tana ranges between â80â° and â170â°, with an abrupt transition from D-enriched to D-depleted waxes between 13,000-11,500 years before present (13-11.5 ka). A similarly abrupt transition from D-depleted to D-enriched waxes occurs ca 8.5-8 ka and is followed by generally D-enriched waxes throughout the late Holocene. Trends in δDwax covary with changes in Northern Hemisphere summer insolation and reflect increased precipitation at Lake Tana during the AHP; however, the transition from D-depleted to D-enriched waxes occurs earlier at Lake Tana (ca 8 ka, vs 5 ka) than in many other regional records, and the amplitude of D-depletion during the AHP is larger at Lake Tana as well. We attribute this early enrichment to a reduction of moisture derived from westerly sources (the Congo Basin and Atlantic Ocean) which we suggest are D-depleted relative to moisture sourced from the east (Indian Ocean) and the north (Red Sea and Mediterranean Sea). Our new record highlights the importance of both the northward migration of the tropical rain belt as well as east-west migration of the Congo Air Boundary to precipitation source and amount during the African Humid Period.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Quaternary Science Reviews - Volume 83, 1 January 2014, Pages 58-67
Journal: Quaternary Science Reviews - Volume 83, 1 January 2014, Pages 58-67
نویسندگان
Kassandra Costa, James Russell, Bronwen Konecky, Henry Lamb,