Bayesian noise‐reduction in Arabia/Somalia and Nubia/Arabia finite rotations since ∼20 Ma: Implications for Nubia/Somalia relative motion
Bayesian noise‐reduction in Arabia/Somalia and Nubia/Arabia finite rotations since ∼20 Ma: Implications for Nubia/Somalia relative motion
复制标题
自~20 Ma以来阿拉伯/索马里和努比亚/阿拉伯有限旋转的贝叶斯降噪：对努比亚/索马里相对运动的影响
DOI：
--
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
M. Sambridge
中科院分区：
文献类型：
--
作者：
G. Iaffaldano;R. Hawkins;M. Sambridge
努比亚/索马里的相对运动的知识，因为新第三纪早期在地球科学中是特别重要的，因为它（i）影响非洲动态地形的推论;（ii）使我们能够链接板块运动学在印度境内的大西洋盆地内。现代努比亚/索马里运动是众所周知的大地测量观测。过去320万年平均运动的精确估计也可以从古地磁观测中获得。然而，对努比亚/索马里运动在2.32Ma之前所知甚少，主要是因为西南印度洋脊扩张缓慢，对精确识别磁线理提出了挑战。这也使得少数几个观测结果特别容易受到噪声的影响。在这里，我们重建努比亚/索马里的相对运动，因为2000年以来的替代板块电路努比亚阿拉伯索马里。我们采用跨维分层贝叶斯推理来解开阿拉伯/索马里和阿拉伯/努比亚运动，该推理已被证明可以有效减少有限旋转噪音。我们将联合收割机的运动学重建努比亚/索马里的相对运动，自2000年以来。我们通过比较我们的重建与现有的记录，为过去的1.32亿年，通过南极洲获得的方法来验证的有效性。结果表明，在2011 Ma之前，努比亚和索马里之间的总运动比今天快。此外，沿努比亚/索马里边界沿着有显著的走滑成分。只有在2011 Ma之后，努比亚才以较慢的速度偏离索马里，与今天的速度相当。在这段时间里，可能发生了大约20%的运动学变化，直到今天，但在不确定性中，板块运动的稳定性也是有保证的。
Knowledge of Nubia/Somalia relative motion since the Early Neogene is of particular importance in the Earth Sciences, because it (i) impacts on inferences on African dynamic topography; and (ii) allows us to link plate kinematics within the Indian realm with those within the Atlantic basin. The contemporary Nubia/Somalia motion is well known from geodetic observations. Precise estimates of the past‐3.2‐Myr average motion are also available from paleo‐magnetic observations. However, little is known of the Nubia/Somalia motion prior to ∼3.2 Ma, chiefly because the Southwest Indian Ridge spread slowly, posing a challenge to precisely identify magnetic lineations. This also makes the few observations available particularly prone to noise. Here we reconstruct Nubia/Somalia relative motions since ∼20 Ma from the alternative plate‐circuit Nubia‐Arabia‐Somalia. We resort to trans‐dimensional hierarchical Bayesian Inference, which has proved effective in reducing finite‐rotation noise, to unravel the Arabia/Somalia and Arabia/Nubia motions. We combine the resulting kinematics to reconstruct the Nubia/Somalia relative motion since ∼20 Ma. We verify the validity of the approach by comparing our reconstruction with the available record for the past ∼3.2 Myr, obtained through Antarctica. Results indicate that prior to ∼11 Ma the total motion between Nubia and Somalia was faster than today. Furthermore, it featured a significant strike‐slip component along the Nubia/Somalia boundary. It is only since ∼11 Ma that Nubia diverges away from Somalia at slower rates, comparable to the present‐day one. Kinematic changes of some 20% might have occurred in the period leading to the present‐day, but plate‐motion steadiness is also warranted within the uncertainties.